Spatiotemporal Variation Of Water Footprint And Its Driving Mechanism In China

The quantity and quality of China's water resources are both at risk with the fast-paced industrialization and urbanization in China.Traditional water resource management,which focuses on the supply side based on the production account is not enough to deal with the mitigation of water scarcity.Water resource management system must urgently change to the demand side.The consumption-based account is the basis for the demand side of the management of water resource.It shows the key objects and the influence of water resource consumption for water resource managers.Many previous studies were conducted on water resource consumption account,while the water quality consumption account has been largely neglected.In this study,water footprint,which combines the water quantity and quality was calculated at national,provincial and residents level.The results provide basic data and guideline for the future demand management of water resources in China.First,the non-competitive input-output model based on a comparable price containing 45 sectors in 1992-2012 was been used for water footprint calculation.The structural decomposition analysis(SDA)was used to show the driving forces behind the varying water footprint in China.The variation of water footprint was decomposed into five factors,namely,population,production structure,consumption structure,economic growth and water footprint intensity.The results showed that the water footprint of China increased by 6%during the given period.The blue water footprint(the amount of surface and ground water consumption)occupied less than 10%of the total water footprint and the grey water footprint(the amount of water resources needed for the assimilation of pollution based on the environmental allowable concentration)occupied the dominant position.Compared with the amount of direct water consumption,more water resources are needed for the assimilation of water pollution emission.The consumption of urban residents plays an increasingly important role in China's water footprint from the consumption perspective.The consumption of urban residents ranked the highest among different consumers in both the blue and grey water footprint of China in 2012.The SDA results showed that population and economic growth contributed mainly to the increase in water footprint,whereas water footprint intensity,production structure and consumption structure were the major drivers of the reduced of water footprint in China.Second,the multiregional input-output model was used to calculate the virtual water flows among provinces of China in 2007.The results showed that the virtual water flows accounted for 23.4%of the total water footprint of China and the that virtual grey water flows were 8.6 times larger than virtual blue water flows.Either the virtual blue water or the grey water shows a tendency of occurring from undeveloped regions to developed regions.The use of indicators related to water quantity to represent virtual water flows in previous studies underestimates its impact on water resources.In addition,virtual water flows are mainly derived from agriculture,chemical industry and petroleum processing and coking industry,accounting for 66.8%,7.1%,and 6.2%of the total virtual water flows,respectively.Virtual water flows intensify both quantity-and quality-induced water scarcity in export regions.If the government neglects the effects of virtual water flows on local water resources,exporting regions will struggle to address water scarcity issues,and importing regions may mitigate water scarcity issues by further outsourcing water use to exporting regions.Water scarcity problems may only be transferred from importing regions to exporting regions rather than being solved.Finally,the water footprint of urban residents in 1992-2012 was calculated using the comparative input-output model containing 45 sectors based on the consumption expenditure data from statistical yearbooks.The results showed that the water footprint per capita of urban residents tended to decrease and the blue water footprint was less than 8%.The consumption expenditure structure of urban residents significantly changed in 1992-2012.The percentage of food consumption in relation to the total expenditure decreased by more than 20%.The percentage of food consumption in the total water footprint held dominant position among different consumption types.The difference in water footprint among groups was smaller than the expenditure,as the high income group spent more money on education and entertainment which represented minimal water footprint.Compared with that of low income groups,the water footprint of high income groups was marked with a minimal change in 1992-2012.The reduction of water footprint because of technology innovation was offset by the increase in consumption expenditure.The current study calculated the water footprint at the national,provincial and urban residential levels.The results showed that the consumption of urban residents and export should be given focus by the demand side management.Economic growth was the major contributor to the increase in water footprint.Virtual water flows accompanied with differences in economic growth among regions intensified the local water scarcity problems.The target of water-saving and emission reduction for provinces should consider the impact of virtual water flows on local water resources.The variation of water footprint for urban residents showed that the food consumption held the dominant position among the different types of consumptions,although the amount and structure of consumption expenditure significantly changed in 1992-2012.The water-saving and emission reduction policies or measures from the supply side are not enough to mitigate the water scarcity problems in China.A policy design from the demand side that should focus on the regulation of consumption is urgently required.