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The virtual water concept has been largely applied in the study of regional, national, and global water flows with particular emphasis on water endowment. Despite water traditionally being managed locally, certain forces (drivers) influence the local water resource availability and hence virtual water exchanges. This study reviews available literature to determine those drivers and their influence on virtual water exchanges. Studies show that the drivers are numerous, and there exist several available literatures providing controversial results leading to a high level of uncertainty in the determination of their relative significance. Possible reasons for the contradicting results are discussed and suggestions made. [ABSTRACT FROM AUTHOR]

Virtual water trade, which underlines the importance of inter-regional commodity transactions for enhancing water management, has often been recommended as an alternative to technological advancements in addressing water scarcity and increasing water savings in dry regions. Sectoral adjustment policies that focus on enhancing the productivity of specific sectors therefore should prioritize sectors with high growth impact potential but low virtual water demand. However, the diverse understanding of the concept and differing assessment techniques employed by various research communities complicate the debates surrounding the policy relevance of the virtual water trade. This study proposes a novel and integrated approach to evaluating virtual water content and flows endogenously, leveraging the advantages of Input-Output and Computable General Equilibrium (CGE) modeling methods. The quantification of the method is exemplified in the case of Uzbekistan (Central Asia), where water is a limited yet essential resource for sustainable economy and environmental systems. Specifically, this study examines the impacts of changes in economy-wide and sector-specific Total Factor Productivity (TFP) and water productivity on water uses, virtual water flows, and economic outcomes. The findings reveal that TFP improvements in livestock and fodder crop production and water productivity enhancements in gardening are recommendable options to constrain the net virtual water trade and enhance economic growth in Uzbekistan. The study also shows a high sensitivity of virtual water flows to technological changes, highlighting the importance of considering options for improving productivity when analyzing the potential of virtual water trade. [Display omitted] • SAM/Input-Output based method of virtual water flow assessment was integrated into a CGE modeling framework. • Water use intensity and virtual water flows were endogenously incorporated into the CGE model. • Virtual water trade is an outcome of technological change policies but not a policy itself. • Improved productivity in livestock and fodder crops production enhance water and income security. • Water productivity improvements in fruits and vegetables production reduce net virtual water exports. [ABSTRACT FROM AUTHOR]

The disclosure of global value chain (GVC) division and cooperation is essential for the rational allocation of water resources and the achievement of trade equality, particularly as the global division of labor becomes more pronounced. Currently, there are limited studies on the global value chain at the sub-national level, with most focusing on virtual water trade (VWT) characteristics between two trading partners, without integrating VWT into the global value chain and overlooking significant cooperation among participants. Here, we characterize the international division of GVC and VWT patterns covering 194 regions (31 regions in China and 163 countries) around the world in 2020, and then examine the inequality between virtual water (VW) and value-added (VA) transfer from both environmental and economic perspectives, focusing on the sub-national scale of China. Our results show that in terms of water consumption responsibilities, considerable heterogeneity can be seen in different regions across China. Furthermore, relying solely on the export of primary products for economic development will lead to inequality in trade between countries. In this study, we trace the characteristics of VWT, taking into account the participation and contribution of regions in numerous GVC linkages. In addition, to make our policy implications more targeted, we refine the study resolution to the sub-national scale. Our results suggest that countries should prioritize consumer responsibility in GVC, reduce the drawbacks of trade barriers, and dispassionately exploit the economic and environmental advantages of water resources. [ABSTRACT FROM AUTHOR]

• This paper constructs the MRIO of YEB. • This paper constructs the spatial–temporal pattern of virtual water trade in the YEB. • This paper discovers that the virtual water trade pattern is contrary to the virtual water strategy hypothesis because of productivity. Cross-regional water allocation within the river basin, coupled with the development of specialized industries based on comparative advantages, can effectively mediate overall water use efficiency. The uneven distribution of water resources and structural contradictions in water usage hinder the sustainable development of water resources in the Yangtze River Economic Belt (YEB). This study aims to address these issues from the perspective of virtual water trade, to facilitate cross-regional water resource allocation and guide structural adjustments in industrial water use, ensuring water security. In this study, we developed a dynamic multi-regional input–output model (MRIO) to explore dynamic change of virtual water trade pattern in the YEB that evolves over time. This model sheds light on evolving virtual water transfer patterns and the nuances of water resource pressure transmission. Additionally, it quantifies sectoral water use variations, pinpointing the cornerstone industries across different regions. The findings are as follows: (1) The pattern of virtual water transfer predominantly towards the developed downstream regions remains unchanged, but regional disparities are gradually diminishing. (2) The upstream regions of the YEB transfer more water resource pressures externally, while the downstream regions do not experience excessive external transfers of water resource pressures. (3) The pattern of Agriculture-driven virtual water transfers is gradually being disrupted. While the upstream regions continue to rely on Agriculture as their pillar industries, the downstream regions are progressively shifting towards tertiary industries such as Service. These results indicate that economic development is the primary driver of changes in the the pattern of virtual water transfer, and economic disparities are a key factor in shaping the latest virtual water transfer. Based on existing policies, there is a need for comprehensive coordination of water resource allocation and strengthening of virtual water trade exchanges between regions to address the uneven distribution of water resources. Additionally, it is necessary to resolve structural water use conflicts by developing specialized economic strengths based on the main industries for virtual water in each region. [ABSTRACT FROM AUTHOR]

Despite the recent droughts in Isfahan province, climatic changes and the rising trend of population growth, as well as development of industrial and agricultural activities, are exposed to the water crisis. Thus, in order to tackle this problem, the essential strategies should including exploring virtual water and water foot print for strategic crops in agricultural sector should be taken into consideration for the management of water supplies at risk. This study was aimed to examine virtual water and ecologic fingerprint of water for the wheat crop in Isfahan Province from the farming year 2006-7 through 2014-15. For this purpose, the quantity of virtual water was extracted using net irrigation demand by NETWAT software and the rate of irrigation efficiency was computed to be 48%. The results indicated that only in 2007, Isfahan province was an exporter of virtual water for the wheat crop, so this province exported about 0.15 billion cubic meters of virtual water to other provinces by wheat exportation, but Isfahan province was the only virtual water in the years (2008-15) and this was due to the annual population rise and the existing drought in this zone. During this period, the rate of the mean annual rate of ecological footprint of water was 5.87 billion cubic meters and Isfahan Province stored this volume of water from the given internal supplies annually, with the mean rate of 0.65 billion cubic meters of virtual water importation at that year.

The present study aimed to assess water footprint in the production and export of rice in India. From recent few years, the water footprint conception in full swing to inward detection around the world. The amplified attention in the water footprint has impelled the trade of commodities between countries. Water footprint in the rice field is a sign of water use that exhibits direct and indirect water usage in the rice field. Rice is an important food crop in India. It accesses the flows of water virtually between countries/regions of the world to illustrate the dependency of countries/regions on water resources with other countries/regions under diverse feasible futures. Hence, it is gaining consequence to calculate the water foot print in production as well as export of rice. The Indian rice production and export of rice was calculated by using international trade and domestic production data. The study results indicated that the global footprint of rice production was 235774 Mm3 per ton which was 53 % of green water footprint, 41 % of blue water footprint and 6 % of grey water footprint for 2018-19. The virtual water flowed in trade was 24354 Mm3/year and the percolation was 16924 Mm3/year since rice is a more water consuming crop. The share of basmati and nonbasmati trade accounted was 16 % and 42 %, respectively. Virtual water trade in rice can be minimized by exporting less water demand and high-value crops, proper water harvesting structures and other agronomic practices. [ABSTRACT FROM AUTHOR]

From the global perspective, this paper utilizes the multi-regional input-output table and water footprint data from the EORA26 database to study China's virtual water trading in the year of 2015. The research results indicate that (1) China was a net exporter of virtual water for all the three types of water footprints: green, blue and grey. In addition, among all the major trading partners, China imported the most amount of virtual water from Germany and the biggest importer of China's virtual water was the US. (2) When the amounts of green, blue and grey water are added up, the largest industry of imported virtual water usage was agriculture, while the textiles and wearing apparel industry exported the largest volume of virtual water. However, when only grey water is considered, China's electrical and machinery industry both imported and exported the highest amounts of virtual water. [ABSTRACT FROM AUTHOR]

The Water Footprint Network (WFN) methodology has emerged as a major framework of/for policy analysis as water problems increase. Being addressed by a growing body of literature, water footprint (WF) accounting has advanced substantially in recent years, whereas its sustainability assessment has lagged behind. For this and other reasons, the suitability of WF in guiding water management and planning has been criticised. Simultaneously, water efficiency has gone through much discussion and a new framework called 'sefficiency' (sustainable efficiency) has been presented. It uses a universal law (water balance) to develop systemic and comprehensive performance indicators, integrating water quantity, pollution and value to reveal their trade-offs in multi-level governance with climate descriptors and stakeholder enablers. This article revisits WF criticisms in six categories and advances the sustainability assessment phase of the WFN framework via sefficiency. Starting from, and critically reviewing, a two-country example presented by Dennis Wichelns, we illustrate, through nine (3x3) scenarios, real possibilities of integrating WF and sefficiency. The results reveal that economic and/or WF perspectives alone are insufficient to improve water decision-making processes, not necessarily guaranteeing an increase in the performance of the full system. Consequently, policy makers should be doubly careful about, for example, WF reductions, if sefficiency also decreases.

Limited water resources, an increase in water demand and a changing climate triggered the development of new concepts for assessment of water demand and water consumption locally and globally. The newest concepts that successfully tackle this issue are water footprint and virtual water trade. Aims of this study are: (1) to define specific water demand for the most important agricultural products in the international trade of the Republic of Serbia, (2) to assess possibilities of an increase in water productivity for those products, and (3) to assess sustainability of water resources in Serbia, based on the ratio of import/export during virtual water trade. Specific water demand for wheat, maize, sunflower, sugar beet and soya bean has been calculated and compared with specific water demand in other countries. Results prove that water productivity can be improved by, for example, using other varieties of crops or modifying cultivation technology. The ratio of imported/exported virtual water quantities for the periods 1995-1999 and 2010- 2013 in Serbia shows that more water was exported than imported. Sustainability of water resources in Serbia will not be endangered even if the export of agricultural products is increased.

There has been a long debate between human needs, resources and the nature of development. Today's research has deepened the debate to include water content and trade. This research aims to identify the limits and dimensions of the virtual water trade. This concept is used in international trade to reconsider the allocation of water resources and increase the efficiency of their use among countries. The concept was first proposed by the scientist Alan in 1993, and after receiving the Stockholm Water Prize in 2008. Interest in the subject has increased. For our part, we have tried to contribute to the enrichment of knowledge in one aspect of the subject focusing two important aspects: dimensions and limitations, through our descriptive analytical approach. [ABSTRACT FROM AUTHOR]

Due to population growth, climatic change, and growing water usage, water scarcity is expected to be a more prevalent issue at the global level. The situation in Australia is even more serious because it is the driest continent and is characterized by larger water footprints in the domestic, agriculture and industrial sectors. Because the largest consumption of freshwater resources is in the agricultural sector (59%), this research undertakes a detailed investigation of the water footprints of agricultural practices in Australia. The analysis of the four highest water footprint crops in Australia revealed that the suitability of various crops is connected to the region and the irrigation efficiencies. A desirable crop in one region may be unsuitable in another. The investigation is further extended to analyze the overall virtual water trade of Australia. Australia's annual virtual water trade balance is adversely biased towards exporting a substantial quantity of water, amounting to 35 km3, per trade data of 2014. It is evident that there is significant potential to reduce water consumption and footprints, and increase the water usage efficiencies, in all sectors. Based on the investigations conducted, it is recommended that the water footprints at each state level be considered at the strategic level. Further detailed analyses are required to reduce the export of a substantial quantity of virtual water considering local demands, export requirements, and production capabilities of regions. [ABSTRACT FROM AUTHOR]

Growth in water use and threatened shortages of water have become increasingly important in the modern world system. Natural resources are exploited extensively by capitalist interests in industrially advanced nations, while the lower strata of the world system, the underdeveloped societies, are left with limited access to natural resources for their productive processes, particularly water resources. We contribute to socio-hydrological research by examining underlying socio-structural factors that play a part in the process of deteriorating conditions of global water resources. Drawing on a world-systems perspective, this study examines how socio-structural forces – world-system position, per capita beef consumption, per capita energy consumption, and urbanization – affect per capita water footprint, which includes an accounting of "virtual water" consumption. We find that per capita beef consumption and per capita energy consumption have significant positive direct effects, and the world-system position has a significant indirect and total effect on per capita water footprint. [ABSTRACT FROM AUTHOR]

The best available high-resolution precipitation, GDP, available freshwater and withdrawal data sets are used in a combined global analysis of physical and economic water scarcity at 50 km resolution. We find that approximately 40.7 million people are living in areas with concurrent severe economic and water-scarcity constraints. These areas are mostly in semi-arid parts of Sub-Saharan Africa, the Middle East and Central Asia. [ABSTRACT FROM AUTHOR]

The concept of virtual water, as a new approach for addressing water shortage and safety issues, can be applied to support sustainable development in water-scarce regions. Using the input-output method, the direct and the complete water use coefficients of industries categorized as primary, secondary, or tertiary, and the spatial flow patterns of the inter-provincial trade in the Gansu province region of China, were explored. The results show that in 2007, 2010, and 2012 the direct and complete water use coefficients of the primary industries were the greatest among the three industry categories, with direct water use coefficients of 1545.58, 882.28, and 762.16, respectively, and complete water use coefficients of 1692.22, 1005.38, and 873.44, respectively; whereas, the direct and complete water use coefficient values of the tertiary industry category were the lowest, with direct water use coefficients of 16.65, 7.74, and 66.89 for 2007, 2010, and 2012, respectively, and complete water use coefficients of 65.46, 66.89, and 72.81 for 2007, 2010, and 2012, respectively. In addition, study results suggest that the volume of virtual water supplied to Gasnu province's local industries has decreased annually, while virtual water exports from the province have increased annually, with the primary industry accounting for 95% of virtual water output. Overall, the virtual water of Gansu province in 2010 showed a net output trend, with a total output of 0.506 billion m³, while in 2007 and 2012 it showed a net input trend with a total input of 0.104 and 1.235 billion m³, respectively. Beijing, Shanghai, Guangdong, Ningxia and other water-scarce areas were the main input, or import source for Gansu's virtual water; during the years studied, these provinces imported more than 50 million m³ individually. Based on these results, it is clear that under the current structure, virtual water is mainly exported to the well-developed coastal areas and their adjacent provinces or other water-abundant regions. Therefore, Gansu province should (1) adjust the industrial structure and develop water-saving and high-tech industries; (2) adjust the current trade pattern to reduce virtual water output while increasing its input to achieve balanced economic development and water resource security. [ABSTRACT FROM AUTHOR]

As water scarcity intensifies worldwide, the equitable allocation of water resources has emerged as a critical challenge. This research investigates the intricate issue of allocating responsibility for virtual water, a concept that quantifies the water embedded in traded commodities. In pursuit of an effective allocation mechanism, we refine an innovative accounting scheme grounded in economic welfare gains arising from externalities. The results show that water-stressed areas in China, such as Xinjiang, significantly contribute to exporting virtual water and is responsible for 70%–85% of the virtual water outflow. Furthermore, more than 50% of virtual water imported from water-rich regions is attributed to these water-stressed areas while their trade partners bear the rest water responsibility. In contrast, southern China's abundant water resources reduce dependence on virtual water trade, leading to fewer responsibilities. Globally, the allocated responsibility for the new accounting mechanism reaches up to 7.5 times higher than for production-based accounting (PBA) and consumption-based accounting (CBA). Our study also reveals that the degree of dependency (price elasticities) plays a pivotal role in shaping the allocation outcomes. The implications of this research are significant for establishing a transparent and accountable framework for sustainable water resource management and facilitating seamless transitions toward sustainability. As global water scarcity intensifies, the redefined responsibility accounting according to the economic welfare is indispensable in addressing immediate and long-term water-related challenges. • We refine a mechanism to reallocate responsibility based on economic welfare gains. • Notable differences exist between results of the new mechanism and current production, consumption, and income-based methods. • Water-stressed areas bear higher proportions of virtual water responsibility. • Price elasticities play a crucial role in determining responsibility allocations. [ABSTRACT FROM AUTHOR]

Shortage of water is considered as one of the most important straits of agricultural development in Iran. The main purpose of this study is to determine virtual water used to pea and bean production and water use efficiency, select the best area for cultivating these two grains and find the virtual water budget for the aforementioned grains. The results showed that among the three provinces main producers of pea in Iran, the highest virtual water of pea belongs to Lorestan with 3534 dm3·kg−1 and the lowest belongs to West Azerbaijan with 2660 dm3·kg−1 in irrigated cultivation. Water use efficiency in irrigated cultivation in Kermanshah and West Azerbaijan are at the same level; however, Kermanshah has enjoyed much more level of virtual water. For beans, the highest amount of virtual water in irrigated cultivation belongs to Lorestan (3651 dm3·kg−1) and the lowest amount refers to Markazi (2725 dm3·kg−1) and also the highest level of water use efficiency for this product refers to Markazi. Also it was found that 160.15 mln m3 of water has been exported from the country water resources by these products so virtual water budget for studied crops were negative.

The water used in the production process of an agricultural or industrial product iscalled "virtual water". In Iran with low average annual precipitation also lack ofavailable water resources, concept of the virtual water and its trade is used as astrategy for optimal operation of water resources in many fields such as waterscarcity, drought and so on. This concept, also, could hold some interesting newopportunities for the field of sustainable consumption. Recently, in Iran, net virtualwater import reached to (15-20)*109 m3 per year and is one out of the top ten virtualimporting countries. In this research, after virtual water applicable conceptsexpressing, virtual water content in some of the agricultural products in the worldhave been compared with products existence in Iran. Additionally, we selectedsome strategic agricultural products, which export and import to the country, andused an algorithm called "Genetic Algorithm", to optimize virtual water usage andtrade according to demands, agricultural situation, production cost andenvironmental condition. Results showed which products how could help optimalwater resources operation and effect of virtual water usage in economic growth.

Water crisis is of utmost importance due to the growing demand and consumption of water, especially in developing countries where its production and food security are facing serious challenges. Virtual water trade has been proposed as one strategy to combat the water scarcity crisis in arid and semi-arid regions. The strategy is based on the import of food and water-intensive supplies from neighboring regions that enjoy adequate supplies of water. Given the fact that the industrial sector has been proposed to serve as the basis of development in Zanjan Province, the present study was conducted to investigate the virtual water trade by the industrial sector in this province. For the purposes of this study, data from the statistical period 2010-2011 were obtained from the Statistical Center of Iran on enterprises employing ten member staffs or above. The data were used to categorize the industries surveyed, their water demands, and products to estimate the quantities of water needed for their continued operation. It was found that the highest quantities of virtual water in Zanjan are allocated to coking and petroleum plants, paper and cellulosic industries, and food and beverage processing factories with average values of 32.70, 26.14, and 11.63 cubic meters per million Rials, respectively. In addition, the total amount of virtual water exported from the industrial units operating in Zanjan Province is estimated at about 3.10 MCM, 50% of which belongs to base metal production. Conclusion: Our findings show that the industrial sector in Zanjan Province is a net exporter of virtual water.

Many water footprint studies have been conducted on those water scarce regions to respond their water crisis, while water rich regions also face water sustainability challenges due to inadequate water management or being virtual water exporter. Therefore, this paper tries to clarify the water footprint and detail virtual water flow features of a water-rich province, namely Yunnan province in China, to pursuit for more enlightenment for water conservation of not only water scarce regions but also water abundant regions. Multi-regional input-output (MRIO) method was adopted for water footprint and virtual water flow calculation. Results showed that the total water footprint of Yunnan was 11.35 billion m3, with 7.98 billion m3 (70%) of internal water footprint, demonstrating that Yunnan was a high water self-sufficient province. Moreover, Yunnan was a net virtual water exporter with a value of 1.18 billion m3, which was not good for Yunnan but was good for water scarce provinces. As for the detailed virtual water flow trade, high water intensity Guangxi, Hunan, Xinjiang were the top three net importers of Yunnan, while low water intensity Guangdong, Shanghai and Zhejiang were the top three export provinces of Yunnan. This did not affect Yunnan, but was not a good phenomenon for water sustainability of whole China. Moreover, agricultural sector was found to be the dominant sector for both virtual water import and export, accounting for about 88% and 86%, respectively. To maintain sustainable water management of both Yunnan and China, policy insights on keeping Yunnan as a net virtual water exporter, making use of its advantage in green water, adjusting trade structure by considering provincial water intensity were proposed. [ABSTRACT FROM AUTHOR]

As a city suffering from serious water resources shortage, Beijing is in urgent need to improve water use efficiency. Based on the method of multi-scale input-output analysis, this work calculates and analyzes the virtual water consumption and trade of Beijing in 2012, and compares the results to that of 2007. The results indicate that the consumption- based water resources use of Beijing were estimated up to 13.95 billion m3 in 2012, which were 3.89 times larger than the production- based direct water resources use (3.59 billion m3). Compared with 2007, the virtual water consumption (23.7%) grew faster than direct water use (11.8%). For all water resources related to Beijing, only 5% was from local water withdrawal, while more than 3/5 was domestically imported from other Chinese regions and about 35% was imported from foreign countries. Meanwhile, about 1/5 of these water resources was consumed to meet Beijing's local final demand, approximately 3/4 was exported to other domestic regions, and 6% was exported to other countries. Beijing changed from a net domestic virtual water importer in 2007 into a net exporter in 2012, and the net domestically exported virtual water in 2012 was 1.1 times larger than the net import in 2007. On the other hand, Beijing changed from a net international virtual water exporter in 2007 into a net importer in 2012, and the net international virtual water import (19.60 billion m3) was 837.2 times larger than the net export (0.02 billion m3) in 2007. Beijing net imported 10.36 billion m3 virtual water in 2012 (all from international trade), which has successfully avoided the over- withdrawal of local water resources. At the same time, Beijing re- exported plenty of internationally imported virtual water to other Chinese regions, which has contributed a lot to alleviate domestic water shortage pressure. In order to reduce domestic water resources use and improve water use efficiency worldwide, Beijing is suggested to strategically increase the international import of mineral, energy, construction and transportation equipment products under the consideration of energy and mineral resource supply security, and to absorb domestic excess capacity in the future. [ABSTRACT FROM AUTHOR]

Water depletion and pollution caused by industrialization have become major environmental concerns worldwide, which are further complicated by the urbanization and globalization. China has become an industrial powerhouse for the world, and its industrial activities-induced water pressure is no longer negligible. This study investigates China's industrial water pressure from final consumption and international export based on water footprint (WF) and dynamic structure decomposition analysis (SDA). The industrial blue and gray WFs with respect to rural consumption, urban consumption, and export are accounted for 2002–2015, and an advanced dynamic SDA model is developed and applied to examining the evolving WFs with 9 socio-economic drivers quantified. Results show that China's water resources pressure is intensified due to the increase of total industrial blue WF (by 47.4%) for 2002–2015, whereas a mitigation of water environment pressure is suggested by the decreasing gray virtual water outflow and total internal gray WF (by 31.9% and 36.4%, respectively). The SDA demonstrates that export scale and urban consumption level are two major drivers of water situation deterioration, which accumulatively contribute 38.3% and 33.0% to the evolving blue and gray WFs, respectively. In contrast, technology development is the dominant contributor alleviating China's water pressure, with absolute contribution proportions of 38.9% and 56.5%, correspondingly. Based on these, export regulation, consumption pattern adjustment and technological innovation are recommended for water policy making. The methodology used in this study can be extended to diagnosing the water issues in other nations/regions as well. • China's industrial blue and gray WFs from rural consumption, urban consumption, and export are separately accounted. • The effects of nine drivers on the WFs are examined using an advanced dynamic structural decomposition analysis model. • Intensified water resources pressure and relieving water environment stress from industrialization are recognized. • Export scale and urban wealth level principally drive up China's industrial WFs. • Technology development dominantly alleviates the water pressure. [ABSTRACT FROM AUTHOR]

Grey water footprint (GWF) accounting has previously been conducted at the global level using a bottom-up approach but lacking detailed industrial information. Here we applied a multi-region input-output approach based on the World Input-Output Database (WIOD) to quantify global GWF of 40 countries/regions with 35 economic sectors. The GWF from both the production perspective (GWFP), and the consumption perspective (GWFC) are quantified. The results show that the global GWFP/GWFC was 1507.9 km3 in 2009. Except for the "Agriculture, Hunting, Forestry and Fishing" sector, the industrial sectors with the largest GWFC were "Food, Beverages and Tobacco", "Construction", "Chemicals and Chemical Products", and "Textiles and Textile Products". The BRIC countries (Brazil, Russia, India, China) had a larger GWFP than their GWFC, which accounted for over half of global GWFP (53.6%), and their GWFP was mainly generated from the production of domestic final demand. In contrast, the OECD29 and EU27 groups of countries i.e. the country groups consisting mainly of economically advanced nations, had larger GWFC than their GWFP. Overall, the OECD29 and EU27 outsourced 134.8 km3 and 64.4 km3 of their grey water respectively, mostly to large newly advanced economies such as the BRIC group of countries, which, in turn, were collectively outsourcing 112 km3 of grey water. Quantitative approaches are thus suggested for development, aimed at shared responsibility for water pollutant discharge among poor exporters and wealthy consumers. • Global Grey Water Footprint (GWF) was quantified from production and consumption perspectives. • Multi-region input-output approach was applied to account for GWF of 40 countries/regions. • Global GWF was 1507.9 km3 in 2009. • BRIC countries accounted for 53.6% of the global GWF from production perspective. • OECD29 and EU27 outsourced 134.8 and 64.4 km3 of their grey water, respectively. [ABSTRACT FROM AUTHOR]

International trade of soybeans has increased substantially over recent decades. Its environmental toll is routinely linked to deforestation and biodiversity loss. However, soybean trade also imposes a huge demand on water and land resources, in individual countries and globally. Such a burden, and its underlying sectoral drivers, is frequently overlooked within the current research and policy agenda around sustainable soybean supply chains. This study evaluates the Virtual Water Trade (VWT) and Virtual Land Trade (VLT) of global soybean trade and reveals which countries and sectors are responsible. Soybean-related VWT and VLT are estimated by combining physical import and export data and associated resource use information from 166 countries during the period 2000–2016. Over this period global virtual soybean-related virtual water and land trade grew by 298% and 250% respectively. In 2016, 812 Gm3 of water use and 41 Mha of land use was directly embodied in international soybean trade. This corresponds to one-third of water and land used to grow soybean globally. Soybean-related VWT and VLT was mainly driven by demand in China, the Netherlands and Mexico, for soybean grown in the US, Brazil and Argentina. Animal feed is responsible for around three-quarters of this resource use. A reduction in the consumption of animal products or switching to direct human consumption of soybeans would reduce the overall demand for soybean production and associated resource use. Although welcome, calls for deforestation-free soybean supply chains do not go far enough to reduce the large, global water and land demand of soybean trade. The research and policy agenda around soybean trade warrants a broader focus on water and land use and whether this represents an efficient, and logical, allocation of resources within the context of food provision and national resource security. [ABSTRACT FROM AUTHOR]

Sustainable food security is one of the policy-making targets in Iran, but water scarcity has always been a challenge to its actualization. Regarding this point, offering policies to address this challenge is essential. On the other hand, wheat is the most important commodity in the food baskets of Iranians, and due to the lack of equality in the supply and demand among the regions, a large amount of wheat is displaced every year. The displacement of wheat has resulted in virtual water trade among the regions and could be a possible solution to manage the water crisis in Iran. With respect to the necessity of research, the present study investigated the effects of economic policies on virtual water trade for wheat using a spatial equilibrium model. Therefore, the aim of this study was to investigate the pattern of virtual water trade flow and welfare changes which resulted from making different economic policies in the wheat market. The results showed that the wheat self-sufficiency policy reduces the total amount of virtual water trade, and will increase pressure on the water resources of Iran. The policy of paying tax and receiving subsidies also significantly affect the flow of virtual water trade. But that happens best when tax revenues are equal to the payment of subsidies. [ABSTRACT FROM AUTHOR]

Abstract This study investigates the water scarcity footprint (WSF) trend of German agricultural imports over recent years, following the principles of the ISO 14046 standard on water footprinting. For this purpose, the import statistics of agricultural goods for the years 2000, 2005, 2010, and 2015 was compiled and linked with the irrigation water consumption during their production as well as with the AWARE water scarcity factors of the country of production. Agricultural imports increased by 62% from 22 to 35 million tons during the analysed period. At the same time, the blue water consumption for agricultural production (i.e., irrigation water) decreased by 13% and the WSF declined by 20%, from 119 to 91 km3 world-equivalents (world-eq.). The decrease in WSF is caused by drop in the cotton imports, while the WSF associated with the imports of other crops increased by 45%. Product-wise, cotton, nuts, and rice contribute to more than half of the total WSF in all analysed years. Despite their high WSF, these products account for only 3% of the imports by mass confirming the relevance of impact based water footprint assessments. Country-wise, main contributors change along the analysed years. In the year 2000, one-quarter of the WSF occurs in Uzbekistan due to cotton imports. Afterwards, the highest WSF arises in Iran and Spain, while the imports from the US dominate the WSF in 2015. The changing trend follows the pattern of production of the hotspots identified on the product level, e.g. nuts, soybeans, and cotton. This study provides information on the water scarcity impacts that the German consumption creates in other countries and may be useful for decision-making processes aiming at optimising water scarcity footprints. Graphical abstract Unlabelled Image Highlights • Water Scarcity Footprint (WSF) of German agricultural imports was calculated. • WSF decreased from 119 to 91 km3 world-eq. between 2000 and 2015. • The imports increased from 22 to 35 million tons between 2000 and 2015. • Imports of cotton , nuts , and rice contribute to almost half of the total WSF. [ABSTRACT FROM AUTHOR]

Abstract Water resources management is particularly challenging in water-scarce basins, where low water availability is combined with a potential water demand exceeding the supply capacity of the natural system. This is the case of the Segura River Basin in south-eastern Spain. This paper aims at analysing the usefulness of incorporating new hydrological data and perspectives to improve the understanding of water availability and management and help promote more integrated water planning in the Segura Basin. In this basin, agriculture amounts to approximately 1366 hm3/year and accounts for 80% of the total blue water use. The forest and agriculture use of soil water amounts to 3065 and 1962 hm3/year, respectively. The unaccounted virtual water trade is also relevant and helps in mitigating water scarcity in the basin. The basin is a net virtual water-exporting region, with an average export of 1598 hm3/year, mainly in the form of fruits and vegetables, and imports approximately 1253 hm3/year, mainly related to feed for pig farms. Virtual water imports are four times larger than the disputed water transfer rate to the Segura Basin from other river basins. Water productivity analyses by sub-sectors are useful in understanding the economic rationale of the basin activities. Two types of agriculture coexist in the basin, namely, intensive industrial agriculture and occupational farming, which maintain the territory and landscape. From a Mediterranean country perspective, the analysis recommends considering climate fluctuations and temporal variability and trends of water availability and use, moving beyond the average values considered in river basin management plans. Groundwater reserve depletion continues to occur at a rate of 231 hm3/year, as water from wells is currently cheaper than using desalinated water in farms, and it does not cause boron-related water quality problems for irrigation. If socially costly administrative measures are not taken, groundwater reserve depletion will continue. Graphical abstract Unlabelled Image Highlights • EU WFD does not address land ecosystems, rainfed agriculture nor virtual water trade. • Analysing all types and origins of water provides insight on impacts and solutions. • The temporal variability and trends analysis helps comply with environmental flows. • Virtual water imports, 1250 hm3/year in the Segura basin, mitigate water scarcity. • Integrating trade, land-use and water planning helps anticipate and solve problems [ABSTRACT FROM AUTHOR]

Graphical abstract Virtual water flows of grain between regions in China. Note: The left side is the grain virtual water export provinces, and the right side is the grain virtual water import provinces. Different colors represent different provinces, and the width of lines represents the relative proportion of virtual water flow. Highlights • Imbalance between grain supply and demand triggers grain virtual water flows (VWFs). • Driving of socio-economic factors on VWFs is evaluated by using structural equation model. • There is a significant causal structure between socio-economic factors and VWFs. • Virtual water trade exerts great pressure on water resources in grain export area. • Current VWFs pattern is unsustainable due to water scarcity and economic imbalance. Abstract Changes in the patterns of regional economic and social development will affect regional agricultural and industrial structures, thereby affecting grain cultivation patterns. Imbalances between the grain supply and demand will trigger interregional grain flow. Grain is a water-intensive product, and virtual water embedded in grain products flows between regions, which will affect the utilization and distribution of regional water resources. This study evaluated the impacts of socio-economic factors on regional grain virtual water flows by using the partial least squares structural equation model (PLS-SEM). Results show that grain production centers in China are being transferred to the northern regions due to the evolution of economic patterns over the past 30 years. Driven by the imbalance between the regional grain supply and demand, the virtual water flow patterns of grain shows a tendency to flow from the northern and western provinces to the southern and eastern provinces. Results of structural equation modeling show that there is a significant causal structure between socio-economic factors and grain virtual water flows. The study indicates that the regional socio-economic pattern and its evolution will affect the grain virtual flow patterns. Consequently, virtual water flows will exert great pressure on water resources in the virtual water export areas, and the expansion of the virtual water export will increase the difficulty of regional water resources systems in supporting regional social and economic sustainable development and grain production, thus posing a potential challenge to China's water resources and grain security. [ABSTRACT FROM AUTHOR]

Despite the recent droughts in Isfahan province, climatic changes and the rising trend of population growth, as well as development of industrial and agricultural activities, are exposed to the water crisis. Thus, in order to tackle this problem, the essential strategies should including exploring virtual water and water foot print for strategic crops in agricultural sector should be taken into consideration for the management of water supplies at risk. This study was aimed to examine virtual water and ecologic fingerprint of water for the wheat crop in Isfahan Province from the farming year 2006-7 through 2014-15. For this purpose, the quantity of virtual water was extracted using net irrigation demand by NETWAT software and the rate of irrigation efficiency was computed to be 48%. The results indicated that only in 2007, Isfahan province was an exporter of virtual water for the wheat crop, so this province exported about 0.15 billion cubic meters of virtual water to other provinces by wheat exportation, but Isfahan province was the only virtual water in the years (2008-15) and this was due to the annual population rise and the existing drought in this zone. During this period, the rate of the mean annual rate of ecological footprint of water was 5.87 billion cubic meters and Isfahan Province stored this volume of water from the given internal supplies annually, with the mean rate of 0.65 billion cubic meters of virtual water importation at that year. [ABSTRACT FROM AUTHOR]

Abstract In the era of globalisation over the last half century, there has been an increase in the exchange of agricultural and food products. This internationalisation process has led to intense environmental pressures on a global level, which has been the case of water resources. This paper studies the determinants of global virtual water trade flows between 1965 and 2010. Using panel data techniques, we have evaluated and quantified the explanatory factors of bilateral virtual water transfers between 70 countries as a result of agri-food trade. We have used the well-known trade gravity equation to explain exchanges of water embodied in agricultural goods on the basis of economic, geographical, institutional and environmental factors. The analysis considers economic country heterogeneity in order to evaluate how trade impacts water resources depending on different development patterns. Our main findings indicate that the traditional economic, institutional and geographic factors played a key role as drivers of virtual water bilateral trade flows between 1965 and 2010. In addition, the natural endowments also exerted a notable influence on these trends. Highlights • The long term determinants of VWT are assessed using a gravity model. • Changes in the country and product composition of VWX and VWM happened from 1965. • Environmental endowments notably determine VWT trends. • Considering income heterogeneity reveals notable divergences in the drivers of VWT. • Dynamic analyses offer a broader framework to study impacts on water through trade. [ABSTRACT FROM AUTHOR]

Traditional methods of assessing virtual water (VW) trade usually overestimate the foreign VW used by a country as the imported VW can also be re-exported and used by the countries other than the initial importer. Due to its ability to provide better estimates of transboundary resource use, the global value chain (GVC) method can provide more precise guidelines for the global policy debate over sustainable resource use. Here, we use GVC analysis based on multi-regional input-output tables to quantify the embodied trade of virtual blue and green water for China in the major agricultural sectors and agro-based industries. We find that China is a net importer of blue VW (2.9 billion m ^3 ) and green VW (57.9 billion m ^3 ) through agricultural commodities. Our results reveal that a large portion of imported blue (37%) and green (17%) VW is re-exported by China and consumed in other countries, representing the overestimated parts of China’s VW import use. These ratios are even higher for individual commodities, including 44% for blue VW for cotton and 22% for green VW for grains. This work demonstrates the importance of improved accounting in VW trade to achieve the sustainable use of global water resources and equitably share responsibility between producers, intermediates, and end-users.

Future transformations in the electricity sector could entail major shifts in power sector technology mixes and electricity trade, with consequences for the trading of virtual water. Previous virtual water trade studies largely focus on historical timeframes. We explore, for the first time, future—through 2050—virtual water trade driven by electricity trade under a range of future electricity sector transformation scenarios using the United States as an example. Under a business-as-usual scenario, virtual water trading in 2050 decreases by 3% relative to 2015 levels. By contrast, virtual water trading increases respectively by 3%, 26%, and 32%, in scenarios characterized by higher socioeconomic growth, higher potential for transmission expansion, and low-carbon transitions. These increases are driven by electricity generation expansion in the western U.S., resulting in higher virtual water trade to the east. In addition, we find that as electricity generation shifts west, an increased amount of nonrenewable groundwater will be consumed to generate electricity that is supplied to the east. Independent of scenario, the US electricity grid largely relies on virtual water exports from only a few states. Our study highlights the need for integrated and national strategies to manage the water and electric systems.

Due to population growth, climatic change, and growing water usage, water scarcity is expected to be a more prevalent issue at the global level. The situation in Australia is even more serious because it is the driest continent and is characterized by larger water footprints in the domestic, agriculture and industrial sectors. Because the largest consumption of freshwater resources is in the agricultural sector (59%), this research undertakes a detailed investigation of the water footprints of agricultural practices in Australia. The analysis of the four highest water footprint crops in Australia revealed that the suitability of various crops is connected to the region and the irrigation efficiencies. A desirable crop in one region may be unsuitable in another. The investigation is further extended to analyze the overall virtual water trade of Australia. Australia’s annual virtual water trade balance is adversely biased towards exporting a substantial quantity of water, amounting to 35 km3, per trade data of 2014. It is evident that there is significant potential to reduce water consumption and footprints, and increase the water usage efficiencies, in all sectors. Based on the investigations conducted, it is recommended that the water footprints at each state level be considered at the strategic level. Further detailed analyses are required to reduce the export of a substantial quantity of virtual water considering local demands, export requirements, and production capabilities of regions.

Growing populations, socio-economic development, the pollution of rivers, and the withdrawal of fresh water are all signs of increasing water scarcity, and with 85% of global use, agriculture is the biggest freshwater user. The water footprint (WF) and virtual water (VW) are concepts used recently for freshwater resources assessment. The WF reflects how much, when and where the water was used whereas VW reveals the volume of water embedded in goods when traded. The first goal of this research is to determine the WF per ton and the WF of production (Mm3/yr) of wheat, barley, rice, and maize in Iraq. The second goal is estimating the quantities of the 4 main cereal crops imported into Iraq and assessing the impact on reducing WF and land savings for 10 years from 2007 to 2016. The results showed that the WF per ton was 1736, 1769, 3694, 2238 m3/ton and the WF of production was 5271, 1475, 997, 820 Mm3/yr for wheat, barley, rice, and maize, respectively. The median total VW imported was 4408 Mm3/yr, the largest volume was 3478 Mm3/yr from wheat, and Iraq saved about 2676 Mm3 of irrigated water and 1,239,539 M ha of land by importing crops every year during 2007−2016. The study revealed the significance of better irrigation management methods to decrease the WF through a selection of crops that need less water and cultivation in rain-fed areas, as well as the use of cereal import to conserve scarce water resources, which is crucial both in terms of water resource management and preservation of the environment. The results of this research could be used as a guideline for better water management practices in Iraq and can provide helpful data for both stakeholders and policymakers.

Abstract Water embodied in traded commodities is important for water sustainability management. This study provides insight into China's water footprint and virtual water trade using three specific water named Green, Blue and Grey. A multi-region input-output analysis at national and sectoral analysis levels from the years 1995 to 2009 is conducted. The evolution and position of China's virtual water trade across a global supply chain are explored through cluster analysis. The results show that China represented 11.2% of the global water footprint in 1995 and 13.6% in 2009. The green virtual water is the largest of China's exports and imports. In general, China is a net exporter of virtual water during this time period. China mainly imports virtual water from the USA, India and Brazil, and mainly exports virtual water to the USA, Japan and Germany. The agriculture sector and the food sector represent the sectors with both the largest import and export virtual water quantities. China's global virtual water trade network has been relatively stable from 1995 to 2009. China has especially close relationships with the USA, Indonesia, India, Canada, Mexico, Brazil and Australia. Trade relations, resource endowment and supply-demand relationships may play key roles in China's global virtual water footprint network rather than geographical location. Finally, policy implications are proposed for China's long term sustainable water management and for global supply chain management in general. Highlights • China's water footprint with its trade partners is investigated. • Three specific water footprints named Green, Blue and Grey are considered. • China represented 11.22% of the global water footprint in 1995 and 13.57% in 2009. • China mainly imports water footprints from the USA, India and Brazil. • China mainly exports water to the USA, Japan and Germany. [ABSTRACT FROM AUTHOR]

This paper introduces a modeling framework for the analysis of real and virtual water flows at national scale. The framework has two components: (1) a national water model that simulates agricultural, industrial and municipal water uses, and available water and land resources; and (2) an international virtual water trade model that captures national virtual water exports and imports related to trade in crops and animal products. This National Water, Food & Trade (NWFT) modeling framework is applied to Egypt, a water-poor country and the world's largest importer of wheat. Egypt's food and water gaps and the country's food (virtual water) imports are estimated over a baseline period (1986–2013) and projected up to 2050 based on four scenarios. Egypt's food and water gaps are growing rapidly as a result of steep population growth and limited water resources. The NWFT modeling framework shows the nexus of the population dynamics, water uses for different sectors, and their compounding effects on Egypt's food gap and water self-sufficiency. The sensitivity analysis reveals that for solving Egypt's water and food problem non-water-based solutions like educational, health, and awareness programs aimed at lowering population growth will be an essential addition to the traditional water resources development solution. Both the national and the global models project similar trends of Egypt's food gap. The NWFT modeling framework can be easily adapted to other nations and regions. [ABSTRACT FROM AUTHOR]

Agriculture is the main consumer of freshwater in the world. The paper described the process of virtual water content and flow in crops. Differences in climatic conditions of different regions in China result in large differences in water consumption during crop growth. The virtual water trade in crops connects water flows within and between regions, linking the actual water consumption with the invisible water trade as a whole. The objective of the paper was supplying the agricultural products virtual water trade evaluation system, determining quantitatively the virtual water flow within the region & regional. Using meteorological and agricultural data from 2003 to 2010, a comprehensive analysis of China's domestic & international virtual water trade of agricultural products has been undertaken. The virtual water for the three primary crops and virtual water trade are discussed. The virtual water content of grain crops in northern & southern China was 1293 m 3 /t & 942 m 3 /t, respectively; the national average value was 1117 m 3 /t; and the regional differences in virtual water content for each crop were significant. China's inter-regional agricultural products virtual water trade was not consistent with water resource endowment expectations. The transfer of crops from northern to southern regions would have a significant impact on the sustainable utilization of water resources and would exacerbate water resources shortages in northern regions. China had a trade surplus in global virtual water trade of agricultural products. The exported agricultural products virtual water amounted to 31.5 billion m 3 /yr., and the imported amount was 145 billion m 3 /yr. The net import of virtual water embedded in agricultural products increased from 44 billion m 3 /yr. in 2003 to 178 billion m 3 /yr. in 2010. It is further concluded that the trend for agricultural products total virtual water, green water, and blue water is that China is increasing its imports year on year. A large increase in imports of agricultural products has led to a decline in the rate of self-sufficiency in domestic agricultural production. The paper provided the basis for the comprehensive evaluation of crop planting structure adjustment, grain import & export, and the potential of regional water resources development and utilization. [ABSTRACT FROM AUTHOR]