Virtual scarce water in China

Virtual flows of aquatic heavy metal emissions and associated risk in China

Heavy metal pollution is posing a serious threat to ecosystem and human health in China. In addition to being emitted into the atmosphere, heavy metals generated by industrial processes are also emitted into water bodies. However, there is a lack of research exploring trade-induced aquatic heavy metals (AHM) emissions hidden in cross-regional supply chain networks. Such information can provide both consumer and producer perspectives on stakeholders' responsibility and involve them in pollution control along the entire supply chain including influencing consumption choices. Using a bottom-up AHM emission inventory (including mercury (Hg), cadmium (Cd), chromium (Cr), arsenic (As), and lead (Pb)) in 2010, we firstly accounted for production- and consumption-based AHM emissions and their virtual flows between China's 30 provinces. Additionally, we developed an integrated index, i.e. Equal Risk Pollution Load, to measure the risk associated with five AHM based on the corresponding reference dose. We found that richer provinces Guangdong, Jiangsu and Zhejiang through their consumption of metal products caused aquatic Hg, Cd, As and Pb pollution in provinces with nonferrous-metallic mineral resources such as Hunan, Yunnan, and Inner Mongolia. However, virtual aquatic Cr emissions were incurred in richer coastal regions (e.g. Guangdong, Zhejiang) for producing and exporting high value added products (electroplated products, printed circuit board and leather products) to less developed inland provinces. Finally, we propose measures from a supply chain perspective to mitigate aquatic pollution.

Can virtual water trade save water resources?

At times, certain areas of China suffering from water shortages. While China's government is spurring innovation and infrastructure to help head off such problems, it may be that some water conservation could help as well. It is well-known that water is embodied in traded goods-so called "virtual water trade" (VWT). In China, it seems that many water-poor areas are perversely engaged in VWT. Further, China is engaging in the global trend of fragmentation in production, even as an interregional phenomenon. Perhaps something could be learned about conserving or reducing VWT, if we knew where and how it is practiced. Given some proximate causes, perhaps viable policies could be formulated. To this end, we employ China's multiregional input-output tables straddling two periods to trace the trade of a given region's three types of goods: local final goods, local intermediate goods, and goods that shipped to other regions and countries. We find that goods traded interregionally in China in 2012 embodied 30.4% of all water used nationwide. Nationwide, water use increased substantially over 2007-2012 due to greater shipment volumes of water-intensive products. In fact, as suspected, the rise in value chain-related trade became a major contributing factor. Coastal areas tended to be net receivers of VWT from interior provinces, although reasons differed, e.g. Shanghai received more to fulfill final demand (67.8% of net inflow) and Zhejiang for value-chain related trade (40.2% of net inflow). In sum, the variety of our findings reveals an urgent need to consider trade types and water scarcity when developing water resource allocation and conservation policies.

Sensitivity of sectoral CO2 emissions to demand and supply pattern changes in China

To realize the emission reduction targets, it is essential to understand how technical and structural variations of an economy can lead to emission changes. This paper establishes the carbon dioxide (CO₂) emissions elasticity indicators of technical and final demand coefficients from the demand perspective as well as allocation and primary input coefficients from the supply perspective, based on the input-output technique combined with sensitivity analysis. We apply these indicators to the Chinese economy for the year 2012. The results show that with every 1% decrease of self-supplied intermediate products in the Production and supply of electricity and heat and Smelting and pressing of ferrous metals (the two largest CO₂ emitting sectors) could reduce CO₂ emissions from the whole economy by 20.6 Mt and 11.3 Mt from the demand perspective, accounting for 0.22% and 0.12% of the national total CO₂ emissions, respectively. It could also mitigate 22.2 Mt and 8.7 Mt from the supply perspective, accounting for 0.24% and 0.09% of the national total, respectively. In addition, 1% decrease of final demand coefficient of the Construction in Capital Formation could exert great indirect effects on many sectors, and lead to 37.4 Mt (0.40%) emission reduction from the whole economy. The absolute reduction due to the variation of primary input coefficients is relatively small. By analyzing these important intersectoral linkages of CO₂ emissions within the economy from both demand and supply perspectives, the most important economic transactions between sectors as well as supply and demand patterns to reduce emissions are identified. These results can help guide the development of potential effective emission mitigation policies and the methods can also be applied to other countries and regions.

Water Degradation by China’s Fossil Fuels Production: A Life Cycle Assessment Based on an Input–Output Model

Fossil energy production not only aggravates water depletion but also severely contaminates water resources. This study employed a mixed-unit input–output model to give a life cycle assessment of national average water degradation in production of common types of fossil fuels in China. The results show that the amount of grey water generated is much more than that of consumptive and withdrawn water in all cases. Although there is a high discharge amount of chemical oxygen demand (COD) in fossil fuel production, the pollutants of petroleum (PE) and volatile phenols (VP) require more dilution water than COD. PE is the greatest contributor to water degradation caused by primary fossil fuels, while VP pollution is prominent in production of upgraded fossil fuels. Basically, the main causes of water degradation, PE and VP discharge, occurs at coal mines, oil fields, refinery plants, and coking factories, rather than in the upstream sectors. A scenario analysis showed that water pollution can be significantly reduced if VP discharge in the coking process is controlled to be at the standard concentration. PE requires a standard withalower discharge concentration in order to further mitigate water pollution in production of fossil fuels. The coal production industry has a much lower pollutant removal rate but spends more on wastewater treatment, up to 12% of its profit. The other fossil fuel industries have high removal rates of PE and VP (97%–99%) and thus demand technological renovation to further remove those pollutants at a low concentration.

Driving Factors of Agricultural Virtual Water Trade between China and the Belt and Road Countries

China proposed the Belt and Road Initiative (BRI), an unprecedented development strategy in terms of scope and scale, to increase the connectivity with the rest of the world by infrastructure development and trade activities. Recently, more attention has been directed to the environmental implications of the international trade activities under this initiative, which contributes to the development of a green, i.e. environmentally friendly, partnership. This study examines the evolution of virtual water trade in relation to agricultural products between China and BRI countries during 2000-2016. The Logarithmic Mean Divisia Index (LMDI) method is adopted for uncovering the driving factors underlying the trade imbalance, as well as the major virtual water exports. Results reveal that China has experienced the shift from a net virtual water exporter to a net importer. At the regional level, Southeastern Asia and Southern Asia are the major net virtual water exporters to China, and Eastern Asia is the major importer. For the selected export countries, an increase in proportion of trade in relation to domestic production significantly contributes to their virtual water export, while water intensity could decrease virtual water export for most export countries. As for the driving forces behind the imbalance of virtual water trade, trade structure was an obvious positive effect, while the effects of water intensity, product structure, and trade scale shifted in favor of virtual water outflows from BRI countries to China in 2008. Massive global water loss has incurred, indicating the inefficiency of this partnership in relation to freshwater. A closer trade relationship is established between China and BRI countries, and relevant environment implications are identified. Policy implications are proposed in terms of trade structure, relationship of trade and domestic production, and international cooperation. This study provides valuable insights into the equity and sustainability of historic trade activities with respect to freshwater resources.

Explaining virtual water trade: A spatial-temporal analysis of the comparative advantage of land, labor and water in China

The well-known "virtual water hypothesis" states that water-deficient regions/countries could alleviate water stress through importing water-intensive products from water-abundant regions/countries. Although observed trading patterns do often not support this hypothesis, there is a lack of research to explore the reasons why trade patterns often do not support the intuitive virtual water hypothesis. To fill this important gap, we introduce comparative advantage theory in a quantitative way to track the driving forces of net virtual water export based on the spatial-temporal distribution of resource productivity and opportunity costs of land, labor and water use in agricultural and non-agricultural sectors across Chinese provinces between 1995 and 2015. The results show that regional differences in land productivity between agricultural and non-agricultural sectors are the main forces determining the pattern of virtual water flows across major regions, and other resources such as labor and water have played only a limited role. Our study shows that the current market forces reflect the scarcity of land resources, but does not reflect the water scarcity in the context of interregional trade in China. Our findings suggest that the ongoing efforts to increase land productivity of agriculture in the southern regions would contribute to reducing water scarcity in the North and Northeast China Plain.

Clean air for some: Unintended spillover effects of regional air pollution policies

China has enacted a number of ambitious pollution control policies to mitigate air pollution in urban areas. Unintended side effects of these policies to other environmental policy arenas and regions have largely been ignored. To bridge this gap, we use a multiregional input-output model in combination with an atmospheric chemical transport model to simulate clean air policy scenarios and evaluate their environmental impacts on primary PM2.5 and secondary precursor emissions, as well as CO2 emissions and water consumption, in the target region and spillover effects to other regions. Our results show that the reduction in primary PM2.5 and secondary precursor emissions in the target regions comes at the cost of increasing emissions especially in neighboring provinces. Similarly, co-benefits of lower CO2 emissions and reduced water consumption in the target region are achieved at the expense of higher impacts elsewhere, through outsourcing production to less developed regions in China.

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.

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.

Inter-Regional Coordination to Improve Equality in the Agricultural Virtual Water Trade

Sustainable agriculture in China is threatened by rapid socioeconomic development, urbanization, and climate change. In addition, the distribution of freshwater resources between regions is highly unequal, and water shortages are common in arid regions. The virtual water trade can help to ease water shortages in arid areas by utilizing the comparative advantage of water resources in other areas. However, sometimes the patterns of the virtual water trade do not fit the distribution of water resources and, in these instances, inter-regional coordination would help to improve the level of equality in the virtual water trade. We combined the concept of the Gini coefficient with a multi-objective optimization model to investigate the inter-regional coordination of the virtual water trade in an arid region of China. Agricultural data from different regions of Gansu Province in 2014 were used to explore methods of improving the equality of virtual water flow patterns in the agricultural sector. Three constraints (a crop supply constraint, an irrigation water constraint, and an economic benefit constraint) were set up to investigate the relationship between different challenges and the effects of inter-regional coordination. Our results validated the use of the proposed method in Gansu Province and indicated that it could be applied to other arid regions. Variations in crop supply, irrigation water, and economic benefits were found among the different constraint scenarios, illustrating the trade-offs between water-saving and agricultural objectives. Our results also showed the balance between various factors, including the equality of the virtual water patterns, water-saving measures, and economic benefits. These results support the effectiveness of inter-regional coordination and indicate that the improvement in equality and the adjustment cost should be balanced. Our findings will help to guide the planning of local crop acreages to achieve the best virtual water balance model between regions.

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.

Water resources conservation and nitrogen pollution reduction under global food trade and agricultural intensification

Global food trade entails virtual flows of agricultural resources and pollution across countries. Here we performed a global-scale assessment of impacts of international food trade on blue water use, total water use, and nitrogen (N) inputs and on N losses in maize, rice, and wheat production. We simulated baseline conditions for the year 2000 and explored the impacts of an agricultural intensification scenario, in which low-input countries increase N and irrigation inputs to a greater extent than high-input countries. We combined a crop model with the Global Trade Analysis Project model. Results show that food exports generally occurred from regions with lower water and N use intensities, defined here as water and N uses in relation to crop yields, to regions with higher resources use intensities. Globally, food trade thus conserved a large amount of water resources and N applications, and also substantially reduced N losses. The trade-related conservation in blue water use reached 85km³y^-1, accounting for more than half of total blue water use for producing the three crops. Food exported from the USA contributed the largest proportion of global water and N conservation as well as N loss reduction, but also led to substantial export-associated N losses in the country itself. Under the intensification scenario, the converging water and N use intensities across countries result in a more balanced world; crop trade will generally decrease, and global water resources conservation and N pollution reduction associated with the trade will reduce accordingly. The study provides useful information to understand the implications of agricultural intensification for international crop trade, crop water use and N pollution patterns in the world.

Revealing Environmental Inequality Hidden in China's Inter-regional Trade

Trade among regions or countries not only allows the exchange of goods and services but also leads to the transfer of pollution. The unequal exchange of goods and services and associated value added and pollution may be subject to environmental inequality in China given that Chinese provinces are in different development stages. By using the latest multiregional input-output tables and the sectoral air pollutant emission inventory in 2012, we traced emissions and value added along China's domestic supply chains. Here, we show that 62%-76% of the consumption-based air-pollutant emissions of richer regions (Beijing-Tianjin, East Coast and South Coast) were outsourced to other regions; however, approximately 70% of the value added triggered by these region's final consumption was retained within the region. Some provinces in western China, such as Guizhou, Ningxia, and Yunnan, not only incurred net pollution inflows but also suffered a negative balance of value added when trading with rich provinces. Addressing such inequalities could provide not only a basis for determining each province's responsibility for pollution control but also a model for other emerging economies.

Harvesting Water from Air: Using Anhydrous Salt with Sunlight

Atmospheric water is an abundant alternative water resource, equivalent to 6 times the water in all rivers on Earth. This work screens 14 common anhydrous and hydrated salt couples in terms of their physical and chemical stability, water vapor harvesting, and release capacity under relevant application scenarios. Among the salts screened, copper chloride (CuCl₂), copper sulfate (CuSO₄), and magnesium sulfate (MgSO₄) distinguish themselves and are further made into bilayer water collection devices, with the top layer being the photothermal layer, while the bottom layer acts as a salt-loaded fibrous membrane. The water collection devices are capable of capturing water vapor out of the air with low relative humidity (down to 15%) and releasing water under regular and even weakened sunlight (i.e., 0.7 kW/m²). The work shines light on the potential use of anhydrous salt toward producing drinking water in water scarce regions.

Unequal Exchange of Air Pollution and Economic Benefits Embodied in China's Exports

As the world's factory, China has enjoyed huge economic benefits from international export but also suffered severe environmental consequences. Most studies investigating unequal environmental exchange associated with trade took China as a homogeneous entity ignoring considerable inequality and outsourcing of pollution within China. This paper traces the regional mismatch of export-induced economic benefits and environmental costs along national supply chains by using the latest multiregional input-output model and emission inventory for 2012. The results indicate that approximately 56% of the national GDP induced by exports has been received by developed coastal regions, while about 72% of air pollution embodied in national exports, measured as aggregated atmospheric pollutant equivalents (APE), has been mainly incurred by less developed central and western regions. For each yuan of export-induced GDP, developed regions only incurred 0.4-0.6 g APE emissions, whereas less developed regions from western or central China had to suffer 4-8 times the amount of emissions. This is due to poorer regions providing lower value added and higher emission-intensive inputs and having lower environmental standards and less efficient technologies. Our results may pave a way to mitigate the unequal relationship between developed and less developed regions from the perspective of environment-economy nexus.

Virtual Water Scarcity Risk to the Global Trade System

Local water scarcity risk (LWSR, meaning potential economic output losses in water-using sectors due to physical water scarcity) can be transmitted to downstream economies through the globalized supply chains. To understand the vulnerability of the global economy to water scarcity, we examine the impacts of local water scarcity risk on the global trade system from 1995 to 2009. We observe increasingly intensified geographical separation between physical water scarcity and production losses due to water scarcity. We identify top nation-sectors in virtual water scarcity risk (VWSR) exports (indicating local water scarcity risk in each nation transmitted to foreign nations through its exports), including agriculture and utilities in major economies such as China, India, Spain, France, and Turkey. These nation-sectors are critical to the resilience of the global economy to water scarcity. We also identify top nation-sectors in virtual water scarcity risk imports (indicating each nation's vulnerability to foreign water scarcity risk through the global trade system), highlighting their vulnerability to distant water scarcity. Our findings reveal the need for nations to collaboratively manage and conserve water resources, and lay the foundation for firms in high VWSR-importing sectors to develop strategies to mitigate such risk.

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.

Measuring the environmental sustainability performance of global supply chains: A multi-regional input-output analysis for carbon, sulphur oxide and water footprints

Measuring the performance of environmentally sustainable supply chains instead of chain constitute has become a challenge despite the convergence of the underlining principles of sustainable supply chain management. This challenge is exacerbated by the fact that supply chains are inherently dynamic and complex and also because multiple measures can be used to characterize performances. By identifying some of the critical issues in the literature regarding performance measurements, this paper contributes to the existing body of literature by adopting an environmental performance measurement approach for economic sectors. It uses economic sectors and evaluates them on a sectoral level in specific countries as well as part of the Global Value Chain based on the established multi-regional input-output (MRIO) modeling framework. The MRIO model has been used to calculate direct and indirect (that is supply chain or upstream) environmental effects such as CO₂, SO₂, biodiversity, water consumption and pollution to name just a few of the applications. In this paper we use MRIO analysis to calculate emissions and resource consumption intensities and footprints, direct and indirect impacts, and net emission flows between countries. These are exemplified by using carbon emissions, sulphur oxide emissions and water use in two highly polluting industries; Electricity production and Chemical industry in 33 countries, including the EU-27, Brazil, India and China, the USA, Canada and Japan from 1995 to 2009. Some of the highlights include: On average, direct carbon emissions in the electricity sector across all 27 member states of the EU was estimated to be 1368 million tons and indirect carbon emissions to be 470.7 million tons per year representing 25.6% of the EU-27 total carbon emissions related to this sector. It was also observed that from 2004, sulphur oxide emissions intensities in electricity production in India and China have remained relatively constant at about 62.8 gSO_x/, respectively, $ and 84.4 gSO_x/$ although being higher than in other countries. In terms of water use, the high water use intensity in China (1040.27 L/$) and India (961.63 L/$), which are among the highest in the sector in the electricity sector is exacerbated by both countries being ranked as High Water Stress Risk countries. The paper also highlights many advantages of the MRIO approach including: a 15-year time series study (which provides a measurement of environmental performance of key industries and an opportunity to assess technical and technological change during the investigated time period), a supply chain approach that provides a consistent methodological framework and accounts for all upstream supply chain environmental impacts throughout entire global supply chains. The paper also discusses the implications of the study to environmental sustainability performance measurement in terms of the level of analysis from a value chain hierarchy perspective, methodological issues, performance indicators, environmental exchanges and policy relevance.

The effect of inter-annual variability of consumption, production, trade and climate on crop-related green and blue water footprints and inter-regional virtual water trade: A study for China (1978-2008)

Previous studies into the relation between human consumption and indirect water resources use have unveiled the remote connections in virtual water (VW) trade networks, which show how communities externalize their water footprint (WF) to places far beyond their own region, but little has been done to understand variability in time. This study quantifies the effect of inter-annual variability of consumption, production, trade and climate on WF and VW trade, using China over the period 1978-2008 as a case study. Evapotranspiration, crop yields and green and blue WFs of crops are estimated at a 5 × 5 arc-minute resolution for 22 crops, for each year in the study period, thus accounting for climate variability. The results show that crop yield improvements during the study period helped to reduce the national average WF of crop consumption per capita by 23%, with a decreasing contribution to the total from cereals and increasing contribution from oil crops. The total consumptive WFs of national crop consumption and crop production, however, grew by 6% and 7%, respectively. By 2008, 28% of total water consumption in crop fields in China served the production of crops for export to other regions and, on average, 35% of the crop-related WF of a Chinese consumer was outside its own province. Historically, the net VW within China was from the water-rich South to the water-scarce North, but intensifying North-to-South crop trade reversed the net VW flow since 2000, which amounted 6% of North's WF of crop production in 2008. South China thus gradually became dependent on food supply from the water-scarce North. Besides, during the whole study period, China's domestic inter-regional VW flows went dominantly from areas with a relatively large to areas with a relatively small blue WF per unit of crop, which in 2008 resulted in a trade-related blue water loss of 7% of the national total blue WF of crop production. The case of China shows that domestic trade, as governed by economics and governmental policies rather than by regional differences in water endowments, determines inter-regional water dependencies and may worsen rather than relieve the water scarcity in a country.

Global impacts of energy demand on the freshwater resources of nations

The growing geographic disconnect between consumption of goods, the extraction and processing of resources, and the environmental impacts associated with production activities makes it crucial to factor global trade into sustainability assessments. Using an empirically validated environmentally extended global trade model, we examine the relationship between two key resources underpinning economies and human well--being-energy and freshwater. A comparison of three energy sectors (petroleum, gas, and electricity) reveals that freshwater consumption associated with gas and electricity production is largely confined within the territorial boundaries where demand originates. This finding contrasts with petroleum, which exhibits a varying ratio of territorial to international freshwater consumption, depending on the origin of demand. For example, although the United States and China have similar demand associated with the petroleum sector, international freshwater consumption is three times higher for the former than the latter. Based on mapping patterns of freshwater consumption associated with energy sectors at subnational scales, our analysis also reveals concordance between pressure on freshwater resources associated with energy production and freshwater scarcity in a number of river basins globally. These energy-driven pressures on freshwater resources in areas distant from the origin of energy demand complicate the design of policy to ensure security of fresh water and energy supply. Although much of the debate around energy is focused on greenhouse gas emissions, our findings highlight the need to consider the full range of consequences of energy production when designing policy.

Ecological network analysis for a virtual water network

The notions of virtual water flows provide important indicators to manifest the water consumption and allocation between different sectors via product transactions. However, the configuration of virtual water network (VWN) still needs further investigation to identify the water interdependency among different sectors as well as the network efficiency and stability in a socio-economic system. Ecological network analysis is chosen as a useful tool to examine the structure and function of VWN and the interactions among its sectors. A balance analysis of efficiency and redundancy is also conducted to describe the robustness (RVWN) of VWN. Then, network control analysis and network utility analysis are performed to investigate the dominant sectors and pathways for virtual water circulation and the mutual relationships between pairwise sectors. A case study of the Heihe River Basin in China shows that the balance between efficiency and redundancy is situated on the left side of the robustness curve with less efficiency and higher redundancy. The forestation, herding and fishing sectors and industrial sectors are found to be the main controllers. The network tends to be more mutualistic and synergic, though some competitive relationships that weaken the virtual water circulation still exist.

Driving force analysis of the agricultural water footprint in China based on the LMDI method

China's water scarcity problems have become more severe because of the unprecedented economic development and population explosion. Considering agriculture's large share of water consumption, obtaining a clear understanding of Chinese agricultural consumptive water use plays a key role in addressing China's water resource stress and providing appropriate water mitigation policies. We account for the Chinese agricultural water footprint from 1990 to 2009 based on bottom up approach. Then, the underlying driving forces are decomposed into diet structure effect, efficiency effect, economic activity effect, and population effect, and analyzed by applying a log-mean Divisia index (LMDI) model. The results reveal that the Chinese agricultural water footprint has risen from the 94.1 Gm3 in 1990 to 141 Gm3 in 2009. The economic activity effect is the largest positive contributor to promoting the water footprint growth, followed by the population effect and diet structure effect. Although water efficiency improvement as a significant negative effect has reduced overall water footprint, the water footprint decline from water efficiency improvement cannot compensate for the huge increase from the three positive driving factors. The combination of water efficiency improvement and dietary structure adjustment is the most effective approach for controlling the Chinese agricultural water footprint's further growth.

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.