National water footprint in an input–output framework—A case study of China 2002

Analysis of China's regional differences in water consumption based on spatial structural decomposition analysis model

Analyzing the factors that affect the spatial differences in production water consumption in China is necessary to implement its most stringent water resource management system effectively. Based on the input-output tables of 31 provinces and the water-consumption data of provinces by sectors in 2017, the water consumption-economy input-output tables of 31 provinces are constructed. The spatial structural decomposition analysis method is used to analyze the impact of technology level, economic scale, and regional characteristics on spatial differences in production water consumption. The final demand effect is then decomposed into final demand sectoral structural effect, final demand distribution structure effect, population-scale effect, and consumption-level effect. The results show that production water consumption depends on the economic scale and regional characteristics. Xinjiang, Jiangsu, Guangdong, Heilongjiang, and most provinces in the central region use more production water than the average level, while those in the Beijing-Tianjin region and most in the North-west region use less than average. The decomposition results show that the technical and the final demand effects are the main factors for the spatial differences. The impact of population-scale and consumption-level contribute the most to the final demand effect.

Water footprint and virtual water trade analysis in water-rich basins: Case of the Chaohu Lake Basin in China

Water footprints and virtual water are widely used as essential tools for water use and conservation analysis of basins worldwide. Despite the importance of water-rich basins as the main force for water-saving, water use analysis has been mainly for water-scarce basins rather than water-rich basins in the existing literature. To fill the gap, in this paper, we investigate the water footprint and virtual water trade in a water-rich basin, namely the Chaohu Lake Basin in China, from 2007 to 2017 using input-output analysis. The results show that: (1) Water use efficiency in the Chaohu Lake Basin was significantly improved. The overall trend of the water intensity was declining, decreasing by 10.21 % in 2017 versus 2012; (2) The internal and external water footprints showed an upward trend, and the growth rate of total water footprint was 36.66 %; (3) The basin was a net virtual water exporter, but the net export flows of virtual water has decreased significantly. The virtual water net export flow decreased by 0.12 billion m³ in 2017 versus 2012; (4) Water resources in the basin were mainly used locally, and its supply to other provinces was minimal. Compared with some water-scarce basins such as the Heihe River Basin and Haihe River Basin, the Chaohu Lake Basin shows significant gaps in the virtual water export flow per capita and behaves differently in the proportion of virtual water transfer. Based on the above findings, we conclude with some guidance and implications for local governments and policymakers.

Using Deep Learning to Fill Data Gaps in Environmental Footprint Accounting

Environmental footprint accounting relies on economic input-output (IO) models. However, the compilation of IO models is costly and time-consuming, leading to the lack of timely detailed IO data. The RAS method is traditionally used to predict future IO tables but suffers from doubts for unreliable estimations. Here we develop a machine learning-augmented method to improve the accuracy of the prediction of IO tables using the US summary-level tables as a demonstration. The model is constructed by combining the RAS method with a deep neural network (DNN) model in which the RAS method provides a baseline prediction and the DNN model makes further improvements on the areas where RAS tended to have poor performance. Our results show that the DNN model can significantly improve the performance on those areas in IO tables for short-term prediction (one year) where RAS alone has poor performance, R² improved from 0.6412 to 0.8726, and median APE decreased from 37.49% to 11.35%. For long-term prediction (5 years), the improvements are even more significant where the R² is improved from 0.5271 to 0.7893 and median average percentage error is decreased from 51.12% to 18.26%. Our case study on evaluating the US carbon footprint accounts based on the estimated IO table also demonstrates the applicability of the model. Our method can help generate timely IO tables to provide fundamental data for a variety of environmental footprint analyses.

Allocating environmental costs of China's rare earth production to global consumption

China provides over 80% of global rare earth (RE) that caused serious domestic environmental impacts. However, how much RE-related pollution was transferred to China along global supply chain remains poorly understood. Here we, for the first time, established the RE industry-specific input-output approaches to trace environmental costs transfer through China's RE exports from whole supply chain perspective. We found that foreign consumption contributed over half of the environmental costs from China's RE production, with a gross value increasing from $4.8 billion (65% of total environmental costs) in 2010 to $5.4 billion in 2015 (74% of total environmental costs). Countries in the East Asia (i.e., Japan and South Korea) made the largest contribution (27-37%) to the exports induced environmental costs, followed by North America (i.e., the United States, Mexico, and Canada) with a contribution of 20-27% and the rest East Asia (including countries in Asia-Pacific except China Mainland, by 16-23%). Exports induced environmental costs were mainly from RE raw materials (60%) and high value-added products (22%). Suggestions such as rationalizing RE cost as well as production- and consumption-based measures to mitigate environmental impacts were proposed to enhance RE utilities for global sustainable development.

Assessing sectoral water stress states from the demand-side perspective through water footprint dimensions decomposition

Due to its essentiality and scarcity, water is subject to stress from the supply and demand side. The SDG and many methods for assessing water stress (WS) are based on water supply, even though the total water supply is uncontrollable by humans in the short term. Conversely, from a water demand perspective, WS arises from the deliberate and manageable use of water to produce goods and services, with few methods proposing to evaluate WS. We propose a method to assess the sectoral demand-side water stress states (DWSS) to fill this gap. The method comprises a quantitative step followed by a qualitative analysis. Quantitatively, an environmentally extended input-output model integrated Brazilian water resource and economic data for 2010 and 2015, including the imported virtual water in the water footprint calculation. Three dimensions of water footprint (DWF) were calculated: consumptive use of water (CUWF), water consumption (CWF), and return to the environment (REWF). The variations in DWFs over time were used as criteria to define five DWSS ranging from weak to strong. Brazilian economy as a whole presented a moderately weak DWSS. Among economic sectors, the most frequent DWSS was moderately weak, with sixteen sectors. The Livestock and Forestry, fishing, and aquaculture sectors had a strong DWSS, while the Slaughter, meat, and dairy and Public administration sectors had weak DWSS. Despite its limitations, the demand-side analysis can complement the usual method from a supply perspective.

A comparative bibliometric analysis of Chinese and foreign articles in environmental footprint family (EFF) research

Research on environmental footprint family (EFF), including these studies of environmental footprints and footprint family, has been widely applied to environmental impact assessment and sustainability evaluation. Although some bibliometric studies have focused on footprint indicators, there is still the lack of the contrast of Chinese and foreign literature in the field of EFF and the conclusions of successful practices at home and abroad in recent years. Unlike most previous papers, we improve the search strategy for collecting accurate documents data and compare China and foreign from a unified international perspective. Two datasets covering 1103 Chinese and 6011 foreign articles between 1996 and 2019 were collected to compare their bibliometric differences in EFF research. We not only comparatively investigate the overview of Chinese and foreign articles in EFF field based on the objects of publications, journals, authors, and institutions, but also explore their differences in the conceptual and intellectual structure from the aspects of keywords and citation analysis. For example, we can deduce that Chinese articles tend to engage in applied research and lack of theoretical innovations and breakthroughs in this field. Our comparative research results are useful and helpful for the public, policymakers, and researchers in this filed.

Industrial polycyclic aromatic hydrocarbons (PAHs) emissions embodied in domestic trade in China in 2012

Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) emissions cause non-negligible damage to human health and well-being. Effective regional cooperation is urgently required to mitigate PAHs emissions to maintain satisfactory air quality. This study quantified and tracked China's PAHs emissions flows embodied in interprovincial trade. A production-based emissions inventory of 16 U.S. EPA priority PAHs based on commercial energy consumption in China in 2012 was compiled using the emissions factor approach. Then, a multiregional input-output model was constructed to reveal consumption-based emissions and to track the PAHs emissions embodied in the trade of 27 major sectors across 30 regions in China. Key structural paths were also identified using structural path analysis (SPA). In 2012, the total industrial energy-derived PAHs emissions were estimated to be 47.7 tons of BaP-toxic equivalents (8032.7 tons of mass). Shandong, Hebei, and Hubei accounted for more than 24.0% of the production-side PAHs emissions in the whole country. Approximately 30.8% of China's PAHs emissions were embodied in goods consumed outside of the province in which they were produced. PAHs flow tended to start in the western regions and ended in the eastern regions along the coast. The results of the SPA showed that critical paths, such as from the Metallurgy sector to the Construction sector, embodied a large amount of emissions and had the potential to affect the performance of the entire system. By paying attention to the consumption-based accounting as well as the production-based accounting of emissions and by focusing on vital transfer paths, policymakers can devise effective and targeted environmental protection and sustainable development policies in China.

Driving Forces of Food Consumption Water Footprint in North China

The water footprint (WF) vividly links water resources with virtual water of food, providing a novel perspective on food demand and water resources management. This study estimates the per capita WF of food consumption for six provinces in North China. Then, the study applies the logarithmic mean Divisia index method to decompose the driving forces of their WF changes. Results show that the per capita WF of food consumption in Beijing, Tianjin, and Inner Mongolia increases significantly in 2005–2017, whereas that in the other three provinces in North China varies slightly. All provinces have shown the same trend of food structure changes: the grain decreased, whereas the meat increased. In general, the urban effect was positive, and the rural effect was negative for all regions. The urban effects in Beijing and Tianjin played a leading role, whereas the rural effects in the other four provinces played a leading role from 2005–2009. However, the urban effects in all provinces played a leading role in 2010–2017. The WF efficiency increased in each province, and the effect in urban areas is stronger due to the higher water use efficiency. For most provinces, the consumption structure was positive because the diet shifted toward more meat consumption. The food consumption per capita effect was the major driving force in Beijing and Tianjin due to the increased consumption level, whereas the population proportion effect exerted a weak effect. To alleviate the pressure on water resources, further improving water use efficiency in food production and changing the planting structure should be emphasized for all regions in North China.

The Paradox of the Virtual Water Trade Balance in the Mediterranean Region

Climate change, water shortages and desertification threaten the economic and environmental sustainability in the Mediterranean. Limited rainfall and higher temperatures put agricultural production, which relies on water availability, in jeopardy. Thereupon, Mediterranean countries pursue agri-food resilience and water preservation through efficient water policies. Hence, water-deprived areas ought to import rather than produce water-intensive products to maintain water inventories and sustainability consequently. As this study examines the water sustainability for a Mediterranean water-scarce region with a particular focus on agriculture, the virtual water trade balance explores this hypothesis. A regional input–output model is constructed, and then total water consumption and the virtual water flows for each economic sector are estimated to determine the virtual water trade balance of the economy. Results indicate that the study area has a trade deficit and struggles economically but is a net importer of virtual water and secures water sustainability. As this virtual water deficit relies heavily on agriculture and originates in vast total water consumption rather than a large trade deficit, a paradox occurs; water-intensive cultivations and animals that consume 91.75% of water resources end up appearing to be water-saving. Further research is needed to strike a balance between economic growth and environmental protection.

Drivers of dynamic evolution in provincial production water usage: perspective of regional relevance

With the advancement of industrialization and urbanization, the issue of water shortage has become a bottleneck for China's economic development. Based on the structural decomposition analysis and multi-regional input-output tables of China in 2002 and 2012, this paper explores the drivers of the change in China's production water usage from the regional relevance perspective. Results show a significant increase in China's production water usage during the study period. The relationship between production water usage and per capita GDP shows an inverted U-shaped curve, and the economic scale by provinces has been improved, while the trend of production water usage differs. There are rapid increases in production water usage in economically developing provinces, while it is falling sharply in developed provinces. The crucial factors promoting its growth are changes in consumption level, population scale, and regional economic patterns. The technical effect is the most important factor in curbing the growth, followed by effects of final demand sectoral and distribution structure. The provinces and sectors with more production water usage shows higher technical and final demand effects. Therefore, it is necessary to promote water-saving activities, enhance the water-saving technical effect, and optimize final demand structure to promote economic growth with low-water usage.

Indirect effects of carbon taxes on water conservation: A water footprint analysis for China

Water scarcity is a severe problem for regional environmental protection and socioeconomic development, and water footprints are effective tools for evaluating the magnitude of the water scarcity. However, water is closely intertwined with energy. Carbon taxes are an essential policy tool for managing energy use, and could therefore indirectly change the water footprint. Previous research on water footprints has revealed the historical characteristics of water footprints, but has not predicted how these characteristics would change under a carbon tax. Identifying the indirect impacts of carbon taxes on water footprints could therefore offer important information to support more effective energy and water policies. In the present study, we explored the impacts of carbon taxes on water footprints. We established a computable general equilibrium model to predict the effects of carbon taxes on the socioeconomic system, and adopted an input-output model to account for changes in the water footprint. We then used China as a case study. We found that a carbon tax could reduce the total water footprint, even though the water footprint for primary industries increased. In addition, the tax could decrease the virtual water content, and the reduction of virtual water content is the greatest for the secondary industries.

Past, Present, and Future of Virtual Water and Water Footprint

Virtual water and water footprint have received increasing attention. However, no published research has conducted a quantitative and objective review of this field from the perspective of bibliometrics. Therefore, based on the Web of Science Core Collection, this study employs CiteSpace to quantitatively analyze and visualize information about countries, institutions, and authors that have conducted virtual water and water footprint research over the past two decades. As of July 2020, there were 1592 publications on virtual water and water footprint, showing an increasing trend overall. The annual average number of publications was only 7.4 in 1998–2008, while it was 126.5 in 2009–2019. Among them, up to 618 publications in the field of environmental science, accounting for 46%. China was the most productive country with a total of 344 articles, but the Netherlands had the strongest influence with a betweenness centrality of 0.33, indicating its leading position. It is essential to strengthen cooperation between developed (water-rich) and developing (water-poor) countries and to incorporate virtual water into social water cycle research. This study is expected to provide a new perspective for investigating the research frontiers and hot spots of virtual water and water footprint research.

Water Footprint Study Review for Understanding and Resolving Water Issues in China

The water footprint (WF) is a widely recognised and comprehensive indicator of both the direct and indirect appropriation of freshwater. It has been utilised for diverse functions, including as a key indicator of the planetary boundaries and United Nations Sustainable Development Goals. Focusing on the nation with the greatest WF, i.e., China, this study reviews journal articles both in English and Chinese published from January 2003 to June 2020. Using CiteSpace and bibliometric analysis of papers, journals, and keywords, we explore state-of-the-art WF accounting, driving forces, and effects. Visible differences in WF accounting keywords and spatial scales between English and Chinese literature are identified. Reported WF values for the same product varied across studies, and there was a lack of information regarding uncertainties. Key driving factors have been largely investigated for agricultural WFs but not for other sectors. The WF impact analyses primarily assess the environmental effects, ignoring the associated social and economic impacts. The development of WF studies has improved our understanding of water issues in China. However, there are still existing knowledge gaps to be filled to find solutions to WF-related issues.

Transboundary Environmental Footprints of the Urban Food Supply Chain and Mitigation Strategies

Food supply has been the central issue of human development for millennia and has become increasingly critical in an urbanizing world. However, the environmental footprints and associated mitigation strategies of food consumption have rarely been comprehensively characterized at urban or regional scales. Here, we analyze the water, carbon, reactive nitrogen, and phosphorus footprints of food consumption in Chinese urban regions and demonstrate how such information can help to formulate tailored mitigation strategies. The results show that in three of the largest urban regions of China, 44-93% of the four footprints are embodied in transboundary food supply. The size of the footprints and the effectiveness of mitigation measures in food supply chain vary across the environmental footprints and urban regions. However, targeting agriculture and food processing sectors in Hebei, Shandong, and Henan provinces can reduce these footprints by up to 47%. Our findings show that the analysis of the environmental footprints along the transboundary food supply chains could inform individualized and effective mitigation targets and strategies.

Identification of key sectors of water resource utilization in China from the perspective of water footprint

We identified the key sectors of water resource use in China from the perspective of the water footprint to improve the use of water resources. The empirical results showed that there were six key sectors (including Crop Cultivation; Forestry; Livestock and Livestock Products; Fishery, Technical Services for Agriculture, Forestry, Livestock and Fishing; Other Food Products, and Scrap and Waste) for water consumption in China in 2015.We analyzed the use of green water, blue water, and grey water. These six sectors accounted for 66.15% of the total impact and 90.76% of the direct impact. Seven key sectors (the six sectors above plus Steel Processing)for the consumption of blue water in China can explain 59.70% of the total impact and 86.94% of the direct effect in 2015. Eight key sectors (Crop cultivation, Other food products, Scrap and Waste, Railway Freight Transport, Highway Freight and Passengers Transport, Water Freight and Passengers Transport, Pipeline Transport, and Health Services) responsible for the consumption of grey water in China in 2015 can explain 81.28% of the total impact and 95.73% of the direct impact. Therefore, the Chinese government should focus on the departments that manage water resources in these sectors when designing water-saving policies and improving water-use efficiency, such as promoting water-saving irrigation technology (including sprinkler irrigation and drip irrigation) in the agricultural sector.

Water usage for energy production and supply in China: Decoupled from industrial growth?

The energy industry, one of the largest water consumers in the socioeconomic system, has been constrained by water scarcity in some areas worldwide. Therefore, decoupling water usage from the energy system is a pressing issue for ensuring energy security and maintaining environmental sustainability. This study applied an input-output analysis and the Tapio decoupling index, which may be considered the first attempt to investigate the decoupling degree between water usage, i.e., the direct water withdrawal for energy production (WWEP) from a production-based perspective and the water footprint for energy supply (WFES) from a consumption-based perspective, and industrial growth for five major energy sectors in China from 2002 to 2015. We found that WWEP was roughly three times higher than WFES for the whole energy industry, and both values underwent a considerable decrease during the study period. Production and supply of electricity and heat (PSEH) contributed most to the total WWEP and WFES, and was mainly responsible for the overall decline. Moreover, WFES exceeded WWEP in Processing of petroleum, coking, and processing of nuclear fuel (PPC) and Production and supply of gas (PSG), whose WEFS values accounted for 36.3% and 12.2%, respectively, of the total WFES in 2015. In terms of the decoupling status, only PSEH achieved strong decoupling in both WWEP and WFES, while PPC and PSG presented a better decoupling performance for WWEP than that for WFES. In contrast, Mining and washing of coal and Extraction of petroleum and natural gas performed relatively worse from both perspectives. These results can help provide a foundation and support for effective water conservation policies from both energy production and energy consumption perspectives.

Exploring Potential Pathways toward Energy-Related Carbon Emission Reduction in Heavy Industrial Regions of China: An Input–Output Approach

It is a very urgent issue to reduce energy-related carbon emissions in China. The three northeastern provinces (Heilongjiang (HLJ), Jilin (JL), and Liaoning (LN)) are typical heavy industrial regions in China, playing an important role in the national carbon emission reduction target. In this study, we analyzed the energy consumption, carbon dioxide (CO2) emissions, and CO2 emission intensity of each sector in the three regions, and we compared them with the national level and those of China’s most developed province Guangdong (GD). Then, based on an input–output (I–O) framework, linkage analysis of production and CO2 emission from sector–system and sector–sector dimensions was conducted. The results showed that the three regions accounted for about 1/10 of China’s energy consumption and 1/6 of China’s CO2 emissions in 2012. In addition, the level of energy structure, CO2 emission intensity, and sectoral structure lagged behind China’s average level, much lower than those for GD. According to the sectoral characteristics of each region and unified backward/forward linkages of production and CO2 emissions, we divided sectoral clusters into those whose development was to be encouraged and those whose development was to be restricted. The results of this paper could provide policy–makers with reference to exploring potential pathways toward energy-related carbon emission reduction in heavy industrial regions.

Water Footprint of Food Consumption by Chinese Residents

Water shortages are a worldwide problem. Virtual water and the water footprint link water resources, human beings and agricultural products, and are effective tools to alleviate water-resources stress. The production of agricultural products consumes a large amount of water, and food is the most basic consumer good for human survival, so it is very necessary to study the water footprint of residents’ food consumption, which is also the weak point of current research on virtual water and the water footprint. This paper aimed to conduct a comprehensive analysis on the water footprint of food consumption in China from the perspectives of urban and rural residents, per capita water footprint, water footprint structure and food consumption structure. The results revealed that the average water footprint of residents’ food consumption was 605.12 billion m3/year, basically showing an upward trend. Guangdong residents had the highest water footprint for food consumption due to the highest population and higher consumption of water-intensive foodstuffs such as grain and meat in their diet. The water footprint of Xizang residents’ food consumption was the lowest followed by Ningxia and Qinghai due to having the least population. The water footprint of food consumption consumed by urban residents was on the rise while that consumed by rural residents was on the decline in China, which was consistent with the changing trend of population. On the whole, the rural population consumed more virtual water embedded in food than the urban population. From the water footprint structure point, the contribution rate of the green water footprint is the largest, reaching 69.36%. The second is the gray water footprint and then the blue water footprint, accounting for 18.71% and 11.93%, respectively. From the perspective of the food consumption structure, grain and pig, beef and mutton consumption contributed significantly to the total water footprint of residents’ food consumption, contributing 37.5% and 22.56%, respectively. The study is helpful for water management and water allocation in rural and urban areas, improving agricultural technology to reduce the gray water footprint and optimizing food consumption structure, such as reducing the consumption of grain and meat.

A Bibliometrics Review of Water Footprint Research in China: 2003–2018

As water security becomes an increasingly important issue, the analysis of the conflict between water supply and demand has gained significance in China. This paper details a bibliometric review of papers published between 2003 and 2018 on the water footprint in China, one of the global hotspots of water resource research. The tendencies and key points of water footprint research were systematically analyzed based on 1564 articles, comprising 1170 original publications in Chinese from the China National Knowledge Infrastructure database and 394 publications in English from the Web of Science database. The results show that the literature associated with water footprint research has expanded significantly. The number of papers published increased from 104 in 2003–2006 to 735 in 2015–2018. Water footprint research has been applied to agricultural, industrial, and regional water resource management to quantify the impact of human activities on water resources and the environment. Water footprint metrics were extracted for regional comparisons. There are obvious regional characteristics of the water footprint in China, but the uncertainty of results makes further investigation necessary. Further water footprint modeling and field experimental research is needed to explore the water–ecological environment under complex systems.

Challenges for Sustainable Water Use in the Urban Industry of Korea Based on the Global Non-Radial Directional Distance Function Model

Since water stress and industrial water pollution pose a huge threat to South Korea’s sustainable water use, it is an urgent task to assess industrial water green use efficiency (GUEIW). Based on the global non-radial directional distance function (GNDDF) model, this paper calculated GUEIW in 16 Korean local governments from 2006 to 2015 using two decomposition indicators: Economic efficiency of industrial water use (ECEIW) and environmental efficiency of industrial water use (ENEIW). The growth of GUEIW is mainly driven by ECEIW, and subsequent environmental problems are obstacles to achieving green use of Korean industrial water. The regional heterogeneity of GUEIW is so important that the downstream region outperformed the upstream region in all three indicators. The government’s efforts to ensure water quality inhibits industrial development in upstream areas, where incomes are much lower than in downstream areas, and downstream industrial areas have to pay upstream industrial areas extra for water. However, regarding upstream industrial areas, low prices easily promote water waste. Because of relatively high water use costs, downstream producers are encouraged to save water. To improve the economic efficiency of industrial water use in upstream areas, advanced water technology should be developed or introduced to make full use of water resources in industrial production.

Assessment of the water resource carrying capacity based on the ecological footprint: a case study in Zhangjiakou City, North China

With the rapid economic development in the past decades, industrialization and urbanization in China has also rapidly developed and will continue in the next decades. However, the regional water shortage has posed great challenges for the sustainable development of big cities especially in north China. Here, we used the water ecological footprint model combined with the system dynamic model to assess the water resource carrying capacity and its sustainability in Zhangjiakou City, a typical water shortage city in north China. The calculated results showed that irrigation was the largest water consumer in Zhangjiakou. There existed a clear gap between water supply and water consumption in this city and such a gap is demonstrated by the high water resource pressure index. Our predicted results based on the water resource ecological footprint and the system dynamic model showed that although the improving water use efficiency has relieved the regional water shortage pressure, the efficiency gained would be to a large degree offset by increased water demands due to the increasing economic development. The annual average water shortage in Zhangjiakou in 2007-2050 would be up to 8.53 × 10⁸ m³, nearly half of the total local average annual water resource. To deal with the severe water shortage over the next three decades, great attention should be paid to scientific water resource managements and water pollution control. This research provides a long-term view of water resource pressure and provides recommendations for a sustainable water use under the rapid regional socioeconomic development.

Transfer of virtual water embodied in food: A new perspective

Food and water are inextricably linked. With the increase of water consumption in irrigation and food growth, water shortage has become an urgent issue. Irrational cross-regional transfer of water embodied in food exacerbates water scarcity and restrict China's sustainable development. Given that, a Virtual Water-Food Nexus Model is developed to quantify the inter-provincial transfer of water embodied in food and to identify the complicated interactions between different provinces. In detail, Environmental Input-Output Analysis is applied to quantitatively estimate the inter-provincial water transfer embodied in food trades. Based on the network constructed by interrelated nature of nexus, the mutual interactions, control situation, and the dominant and weak pathways are examined through the combination of Ecological Network Analysis and Principal Component Analysis. Two new indictors water consumption intensity and water supply capacity are first performed to measure the role of each province from the supply and consume side respectively. It is revealed that interregional food transactions failed to realize water resources dispatching management. Many water-deficient regions suffered from massive virtual water losses through food exports, but water-rich areas still import large quantities of food containing virtual water. Results show that exploitation and competition dominate the ecological relationships between provinces. Agricultural GDP ratio is the indicator which most affect water consumption intensity and water supply capacity. Network-based research contributes more insights into the recognition of water management responsibilities across provinces and municipalities. These findings will provide a scientific support to adjust unreasonable allocation of water resources in China in an attempt to addressing the contradiction between food demand and water shortages.

Water Footprint Allocation under Equity and Efficiency Considerations: A Case Study of the Yangtze River Economic Belt in China

From a water footprint perspective, this paper adopts Gross Domestic Product (GDP) as the influencing factor to construct a lexicographical optimization framework for optimizing water resources allocation under equity and efficiency considerations. This approach consists of a lexicographic allocation of water footprints (LAWF) model and an input-output capacity of water footprints (IOWF) model. The proposed methodology is then applied to allocate water resources in the Yangtze River Economic Belt (YREB) by employing the 2013 cross-sectional data in the area. The results show that: (1) The LAWF scheme signifies reductions in water footprints in each of the YREB administrative units, thereby significantly strengthening their IOWFs. (2) IOWFs are affected by industrial attributes and natural endowments, and the impact tends to vary across different industries and regions. (3) Policy suggestions are proposed to effectively enhance the IOWFs of the weakest industries across the three YREB regions to exploit their natural endowments.

Factors governing variations of provincial consumption-based water footprints in China: An analysis based on comparison with national average

Although several studies have revealed that the consumption-based water footprint (WF) is unequal in space, the contributing factors to this spatial inequality have rarely been quantified. This study addresses this need by quantifying the effects that determine the difference of one region's WF per capita and a benchmark average value. A decomposition framework is developed. Using provincial water uses in China as a case study, this framework breaks down the deviation of one province's per capita WF from the national average value into effects of five key factors, namely, the actual-requisite WF difference, direct water use intensity, economic production structure, consumption level and consumption structure. The structural decomposition analysis is adapted to investigate differences between the provincial WFs and national average value, in contrast to its conventional use for examining changes of an environmental variable over time. The results indicate that the drivers of a high or low WF level in different provinces are diverse. The dominant factors are most often the direct water use intensity and consumption level, which may contribute over 1000 and 400 m³ of per capita WFs per year, respectively. The results assist in the diagnosis of per capita WF for each province. Policy suggestions highlighting feasible institutional or technological arrangements are made for each province, which have the potential to reduce consumption-based WF inequality without compromising living standards of inhabitants.

Exploring the changes and driving forces of water footprints in China from 2002 to 2012: A perspective of final demand

Due to economic development and population growth, the water shortage in China has gradually become increasingly severe. In this paper, by developing an environmentally expanded input-output (IO) model, water footprint in China during 2002-2012 is calculated from the perspective of final demand. Furthermore, a structural decomposition analysis (SDA) model is used to study the driving factors of the water footprint of rural and urban household consumption, gross fixed capital formation and exports. The findings indicate that: 1) the water footprint driven by final demand in China increased by 18.3% during 2002-2012, reaching 617.68 billion m³ in 2012, of which urban household consumption accounts for the highest proportion. 2) Of the different sectors, agricultural commodities have the highest water footprint, accounting for 35% of national water footprint in 2012. 3) In terms of the driving factors, water efficiency inhibits the increase of water footprint regardless of final demand types, while GDP per capita makes a great contribution to its rise. 4) As for rural household consumption, the most important driving factor is the inhibition effects of consumption pattern in water footprint. For urban household consumption, the water footprint is inhibited by consumption pattern but promoted by production structure during 2002-2010. However, it is no longer the case during 2010-2012 that consumption pattern becomes a promoting factor, with production structure being inhibiting one. 5) Regarding gross fixed capital formation, its water footprint increase driven by consumption pattern is only 12.4 billion m³ during 2007-2010. As for exports, consumption pattern causes the decline of water footprint after 2005 and the overall water footprint of exports declines during 2007-2012. Finally, this paper provides policy implications with respect to the promotion of China's water footprint conservation.

Water Footprint and Virtual Water Accounting for China Using a Multi-Regional Input-Output Model

Water footprint (WF) is a measure of the actual appropriation of water resources. WF accounting can provide a scientific basis for the managements of water resources. In this study, a multi-regional input-output model is employed to measure the quantity of blue WF (WF) and inter-provincial virtual water (VW) flows in China for the years of 2007 and 2010. The results show that: (1) China’s total WF increased from 205.42 billion m3 in 2007 to 229.34 billion m3 in 2010. Approximately 42% of the WF was attributed to VW embodied in inter-provincial trade. Xinjiang is the largest province of VW export, whereas Shanghai had the largest net VW inflows. (2) From 2007 to 2010, the share of the agricultural sector in the entire VW trade declined, but was still as high as 82.78%, followed by the industrial sector. (3) The north-to-south and south-to-south patterns were witnessed in the domestic VW flows. The provincial WF variations are found to be affected by the per capital GDP, total water resources, per capita water resources, and urban population. (4) By linking VW with an integrated WAVE+ (water accounting and vulnerability evaluation) factor, it was found that virtual scarce water (VSW) was mainly exported by the provinces in northern China. At the national level, the amounts of VSW inflows were consistently greater than those of VSW outflows for both years, 2007 and 2010, implying an increased pressure on the provinces with water deprivation issues. Overall, these results can provide a basis for refining the spatiotemporal allocation of water resources and mitigating the conflict between water supply and demand in China.

Water footprint characteristic of less developed water-rich regions: Case of Yunnan, China

Rapid industrialization and urbanization pose pressure on water resources in China. Virtual water trade proves to be an increasingly useful tool in water stress alleviation for water-scarce regions, while bringing opportunities and challenges for less developed water-rich regions. In this study, Yunnan, a typical province in southwest China, was selected as the case study area to explore its potential in socio-economic development in the context of water sustainability. Both input-output analysis and structural decomposition analysis on Yunnan's water footprint for the period of 2002-2012 were performed at not only an aggregated level but also a sectoral level. Results show that although the virtual water content of all economic sectors decreased due to technological progress, Yunnan's total water footprint still increased as a result of economic scale expansion. From the sectoral perspective, sectors with large water footprints include construction sector, agriculture sector, food manufacturing & processing sector, and service sector, while metal products sector and food manufacturing & processing sector were the major virtual water exporters, and textile & clothing sector and construction sector were the major importers. Based on local conditions, policy suggestions were proposed, including economic structure and efficiency optimization, technology promotion and appropriate virtual water trade scheme. This study provides valuable insights for regions facing "resource curse" by exploring potential socio-economic progress while ensuring water security.

The role of the water footprint in the context of green marketing

The environmental degradation, because of various factors, such as climate change, human activities, increase of population globally, etc. have brought on pressures on the fresh water supplies that vary on time and space. Consequently, economic, environmental, and social tools have emerged known as footprints, in an effort to examine and measure the needs and consequences of humanity on the Earth's life support systems and take measures towards sustainable development. Furthermore, the constantly worsening environmental conditions have resulted in the cultivation of a green culture among society stakeholders that brought on terms such as green marketing and green products. This paper deals with the water footprint (WF) concept and an effort is performed, to explore through a literature review, in which ways it can contribute to the sustainable development of water use, in the context of green marketing (GM) strategies. The approach of the analysis is based on the discrimination to the following aspects: international scale, national and subnational scale, farmers, business, and consumers, in order to track the affection of each part in water issues. The main findings of the literature review showed that the aforementioned factors are playing a key role in protecting water recourses, by the way they formulate their water use and they are interrelated and interdependent. WFs can be useful in the context of GM, by providing helpful information about direct and indirect water consumption, to every contributor factor in supply chains, to consumers, governments, and water managers.

Blue and Green Water Footprint Assessment for China—A Multi-Region Input–Output Approach

Research on blue and green water footprints (WF) for China has typically been carried out based on bottom-up and top-down approach using a single-region input–output table. However, this research typically lacks detail on the sectoral interrelationships which exist between China and its trading partners in other countries/regions of the world. Here, a multi-region input–output approach using the WIOD database was applied to quantify the blue and green WF for China in 2009. The quantification was conducted from both production (WFP) and consumption (WFC) perspectives. The results show that the total WFP for China in 2009 was 1152.2 km3, second only to India. At 1070.9 km3, China had the largest WFC volume in the world. The internal WF was 953.5 km3, taking the substantial share for both the WFC and WFP. Overall, China’s trade resulted in a net export of 53.5 km3 virtual water. In contrast, the agricultural sector resulted in a net import of 70.6 km3 virtual water to China, with United States, Brazil, and Canada acting as major suppliers. This study suggests that quantifying the WF of China at global level through a MRIO framework is a necessary step towards achieving sustainability for China’s water management.

Worse than imagined: Unidentified virtual water flows in China

The impact of virtual water flows on regional water scarcity in China had been deeply discussed in previous research. However, these studies only focused on water quantity, the impact of virtual water flows on water quality has been largely neglected. In this study, we incorporate the blue water footprint related with water quantity and grey water footprint related with water quality into virtual water flow analysis based on the multiregional input-output model of 2007. The results find that the interprovincial virtual flows accounts for 23.4% of China's water footprint. The virtual grey water flows are 8.65 times greater than the virtual blue water flows; the virtual blue water and grey water flows are 91.8 and 794.6 Gm³/y, respectively. The use of the indicators related with water quantity to represent virtual water flows in previous studies will underestimate their impact on water resources. In addition, the virtual water flows are mainly derived from agriculture, chemical industry and petroleum processing and the coking industry, which account for 66.8%, 7.1% and 6.2% of the total virtual water flows, respectively. Virtual water flows have intensified both quantity- and quality-induced water scarcity of export regions, where low-value-added but water-intensive and high-pollution goods are produced. Our study on virtual water flows can inform effective water use policy for both water resources and water pollution in China. Our methodology about virtual water flows also can be used in global scale or other countries if data available.

Alleviating Pressure on Water Resources: A new approach could be attempted

Water and food safety are two major challenges which the world faces today. Traditional water management focuses on the reduction of water use through improvements in water saving technologies. However, quantitative research is needed to evaluate the effects of changing food consumption patterns on water resources. Here we report the water saving effects of changing diet pattern of the major crops and animal products in mainland China. By using the concepts of water footprint (WF) per weight unit and per calorie unit, provided by 13 primary crop and animal products, the WFs of the 13 agricultural products in each province are compared, and their water/energy conversion efficiencies are analyzed. Then, impacts of different scenarios of changing diet pattern on water consumption were explored. Results show that there are obvious differences between the WF per weight and calorie unit provided by crop and animal products due to the nutritional properties of the agricultural products. Promoting water savings from the food consumption side could give a positive feedback on water consumption. Scenario analysis of adjustments to the diet pattern proves that it is potentially feasible to reach the objective of alleviating stress on water resources while guaranteeing nutritional value of the residents.

Multiregional input-output model for China's farm land and water use

Land and water are the two main drivers of agricultural production. Pressure on farm land and water resources is increasing in China due to rising food demand. Domestic trade affects China's regional farm land and water use by distributing resources associated with the production of goods and services. This study constructs a multiregional input-output model to simultaneously analyze China's farm land and water uses embodied in consumption and interregional trade. Results show a great similarity for both China's farm land and water endowments. Shandong, Henan, Guangdong, and Yunnan are the most important drivers of farm land and water consumption in China, even though they have relatively few land and water resource endowments. Significant net transfers of embodied farm land and water flows are identified from the central and western areas to the eastern area via interregional trade. Heilongjiang is the largest farm land and water supplier, in contrast to Shanghai as the largest receiver. The results help policy makers to comprehensively understand embodied farm land and water flows in a complex economy network. Improving resource utilization efficiency and reshaping the embodied resource trade nexus should be addressed by considering the transfer of regional responsibilities.

Lifting China's water spell

China is a country with significant but unevenly distributed water resources. The water stressed North stays in contrast to the water abundant and polluted South defining China's current water environment. In this paper we use the latest available data sets and adopt structural decomposition analysis for the years 1992 to 2007 to investigate the driving forces behind the emerging water crisis in China. We employ four water indicators in China, that is, freshwater consumption, discharge of COD (chemical oxygen demand) in effluent water, cumulative COD and dilution water requirements for cumulative pollution, to investigate the driving forces behind the emerging crisis. The paper finds water intensity improvements can effectively offset annual freshwater consumption and COD discharge driven by per capita GDP growth, but that it had failed to eliminate cumulative pollution in water bodies. Between 1992 and 2007, 225 million tones of COD accumulated in Chinese water bodies, which would require 3.2-8.5 trillion m(3) freshwater, depending on the water quality of the recipient water bodies to dilute pollution to a minimum reusable standard. Cumulative water pollution is a key driver to pollution induced water scarcity across China. In addition, urban household consumption, export of goods and services, and infrastructure investment are the main factors contributing to accumulated water pollution since 2000.

Virtual scarce water in China

Water footprints and virtual water flows have been promoted as important indicators to characterize human-induced water consumption. However, environmental impacts associated with water consumption are largely neglected in these analyses. Incorporating water scarcity into water consumption allows better understanding of what is causing water scarcity and which regions are suffering from it. In this study, we incorporate water scarcity and ecosystem impacts into multiregional input-output analysis to assess virtual water flows and associated impacts among 30 provinces in China. China, in particular its water-scarce regions, are facing a serious water crisis driven by rapid economic growth. Our findings show that inter-regional flows of virtual water reveal additional insights when water scarcity is taken into account. Consumption in highly developed coastal provinces is largely relying on water resources in the water-scarce northern provinces, such as Xinjiang, Hebei, and Inner Mongolia, thus significantly contributing to the water scarcity in these regions. In addition, many highly developed but water scarce regions, such as Shanghai, Beijing, and Tianjin, are already large importers of net virtual water at the expense of water resource depletion in other water scarce provinces. Thus, increasingly importing water-intensive goods from other water-scarce regions may just shift the pressure to other regions, but the overall water problems may still remain. Using the water footprint as a policy tool to alleviate water shortage may only work when water scarcity is taken into account and virtual water flows from water-poor regions are identified.

Greenhouse gas emission accounting and management of low-carbon community

As the major source of greenhouse gas (GHG) emission, cities have been under tremendous pressure of energy conservation and emission reduction for decades. Community is the main unit of urban housing, public facilities, transportation, and other properties of city's land use. The construction of low-carbon community is an important pathway to realize carbon emission mitigation in the context of rapid urbanization. Therefore, an efficient carbon accounting framework should be proposed for CO₂ emissions mitigation at a subcity level. Based on life-cycle analysis (LCA), a three-tier accounting framework for the carbon emissions of the community is put forward, including emissions from direct fossil fuel combustion, purchased energy (electricity, heat, and water), and supply chain emissions embodied in the consumption of goods. By compiling a detailed CO₂ emission inventory, the magnitude of carbon emissions and the mitigation potential in a typical high-quality community in Beijing are quantified within the accounting framework proposed. Results show that emissions from supply chain emissions embodied in the consumption of goods cannot be ignored. Specific suggestions are also provided for the urban decision makers to achieve the optimal resource allocation and further promotion of low-carbon communities.

Understanding Beijing's water challenge: a decomposition analysis of changes in Beijing's water footprint between 1997 and 2007

Beijing has been experiencing increasing water shortage alongside its astonishing economic growth over the past decades. This study conducts a quasi-dynamic input-output (IO) analysis to investigate changes in Beijing's water footprint (WF) and decompose the effects of contributing factors to the changes during 1997-2007. The analysis distinguishes "internal" and "external" WF to depict connections of Beijing's water use with outside. The results show an increase in Beijing's WF from 4342 million m(3) in 1997 to 5748 million m(3) in 2007. Almost all the increase was attributable to the expansion of the external WF, while the internal WF only changed slightly, indicating a growing dependence of Beijing on external water resources. The decomposition analysis reveals that the technological effect was the principal contributor to offset the WF increase and the structural effect stemmed from the shift of demand toward products of the tertiary industries also contributed to reducing the WF. However, these effects were not sufficient to reverse the expansion of Beijing's WF resulted from the scale effect induced by expansion of final demand and the economic system efficiency effect associated with the growth of trade between Beijing and outside. The study provides insights into Beijing's water challenge and sheds lights on the combating strategies for the future. It is also an endeavor to enhance the policy relevance of the WF studies.