30 Apr Virtual Water: The Unknown Knowns Vinod T R1, Thrivikramji KP2 and Babu Ambat3 1Program Director, 2Professor Emeritus, 3Executive Director Centre for Environment and Development, Thiruvananthapuram
The term “virtual water” began appearing in the water resources literature in the mid-1990s. The concept of Virtual Water was introduced by Tony Allan in the nineties (Allan, 1993; 1994; 1998), when he studied the possibility of importing virtual water as a partial solution to problems of water scarcity in the Middle East. The concept of ‘embedded water’ (which was coined before 1994) has not managed to gain acceptance. The virtual water content of a product is defined as the freshwater “embodied” in the product, not in real sense, but in virtual sense. Other wards, Virtual water can be defined as the water that is required for manufacturing a product or for rendering a service. It refers to the volume of water consumed or polluted for producing the product, measured over its full production chain. A famous equivalence often used by Allan is that a thousand tons of water is necessary to produce a ton of wheat (Allan, 2003; 2011). Indians also paid close attention when virtual water reached the global water agenda at the March 2003 World Water Forum (Kumar and Jain, 2007; Reddy, 2005; Sharma, 2003; Sivakumar, 2004).
Virtual water is a term that links water, food, and trade and is a successful means by which water deficit economies can remedy their deficits. Virtual water happens to be integral to the strategic commodity food and unable to escape a contentious role in discourse on the political economy of food security. The potential role of virtual water is so contentious that those actually managing water and developing water policy in water scarce economies ensure that the concept is kept out of water policy-making discourse (Allan, 2001). Import of water-intensive commodities reduces water demand whereas export of water-intensive commodities raises national water demand and thus enhances water scarcity at local level. By emphasizing the importance of the water content of crops, virtual water is shifting the focus of the discourse from “‘local water use efficiency’ at user level and ‘water allocation efficiency’ at river basin level” to “global water use efficiency” (Hoekstra and Hung, 2005; Beadon and Page, 2010).
Virtual water Vs Water footprint
The ‘virtual water content of a product’ refers to the water volume embodied in the product alone whereas the water footprint of a product is the total volume of freshwater consumed or polluted over the various steps of the production chain. The water footprint of a product is thus a multi-dimensional indicator, whereas virtual water content refers to a volume alone. The aggregate water footprint of the consumers in a nation is defined as the total amount of freshwater that is used to produce the producers consumed by the inhabitants of the nation. The water footprint of national consumption is calculated as the total use of domestic water resources plus the nation’s gross virtual water import minus the nation’s gross virtual-water export.
The “green” and “blue” components of virtual water are also well studied. “Green water” is used to denote effective rainfall or soil moisture that is used directly by plants, while “blue water” denotes water in rivers, lakes, aquifers, or reservoirs (Falkenmark and Rockström, 2004; Rost et al., 2008). As such, blue water generally refers to water that can be delivered for irrigation or made available for alternative uses, while green water must be used directly from the soil profile.
Understanding virtual water flows
VW differs from direct water use, in that the consumer does not perceive it and once used in production, it is embodied in consumable commodities. For purposes of analyzing flows of VW, it is important to keep in mind that VW is passed on between intermediate consumers, before it reaches the final user beyond which its flow ceases. Similarly, the VW flow between two nations or provinces within a nation is the volume of virtual water contained in the traded product between the nations or regions. The analysis of Global VW flows was introduced by Hoekstra and Hung (2002), Hoekstra (2003), Chapagain and Hoekstra (2003) and Zimmer and Renault (2003). Hoekstra and Chapagain (2008) estimated that the global VW flow is of the order of 1625 billion m3/yr during 1997-2001, of which 61% (i.e., 987 billion m3/yr) was linked to trade of crops and crop products, 17% (i.e., 276 billion m3/yr) to livestock and livestock products and the remaining 22% (362 billion m3/yr) to industrial products.
Fig.1 Schematic of virtual water flows (After Hoekstra et al., 2011)
Virtual water trade
Rising water demand due to population growth, industrial development and urbanization, warranted economically efficient use of water resources. It is predicted that by 2025, two-thirds of the world population could be under “stress conditions” (500-1000 m3 y-1 per capita), and 1800 million people are expected to be living in countries or regions with “absolute water scarcity” (<500 m3 y-1 per capita). Concept of VW and its trade that ensued are bestowed with widespread optimism for its perceived potential or promise to solve water insecurity, but at the same time circumventing major political and social costs. By “VW trade” what is meant is the trade of water in virtual form or state, when a product or produce is traded between two provinces within a nation or between nations. Again, VW allows governments to conceal or tide over water scarcity by importing water intensive crops. Chapagain and Hoekstra (2004) published “The Water Footprint of Nations” – the first global study – analyzing VW flows among the nations during 1997-2001 and based on international trade of crop, livestock and industrial products.
Fig.2 Net global VW imports, 1997-2001
(after Hoekstra and Chapagain, 2008)
A recent report (Proceedings of the National Academy of Sciences, 2012) revealed that China is the country with largest water footprint of consumption in the world (1,368 Gm3/yr), followed by India (1,145 Gm3 y-1 ) and the United States (821 Gm3 y-1). But the major gross VW exporters are the United States (314 Gm3 y -1), China (143 Gm3 y-1), India (125 Gm3 y-1), Brazil (112 Gm3 y-1), Argentina (98 Gm3 y-1), Canada (91 Gm3y-1), Australia (89 Gm3 y-1), Indonesia (72 Gm3y-1 ), France (65 Gm3 y-1) and Germany (64 Gm3 y-1). The United States, Pakistan, India, Australia, Uzbekistan, China, and Turkey are also the largest blue virtual water exporters, accounting for 49 per cent of the global blue virtual water export. Yet all of these countries are partially under water stress, which raises the question whether or not the implicit or explicit choice to utilize the limited national blue water resources for export products is sustainable and most efficient.
Virtual water trade in India
In India, with a rapidly growing population and improving living standards, the water requirement of India is increasing while the per capita availability of water resources is declining day by day. According to FAO (2010), during 2001-2005, India exported 228.61 Gm3 of VW (average= 45.72 Gm3 y-1 ) and imported 358.27 Gm3 of VW (average = 71.65 Gm3 y-1 ). In fact, India was a net importer of 25.93 Gm3/yr of virtual water related to crop and livestock products during the same time frame.
Based on certain assumptions about interstate movement of agricultural products, Kampman (2007) estimated the mean annual import (or export) of virtual water among the Indian states (see Fig.3). Kampman (2007) the states of Punjab, Uttar Pradesh and Haryana are the largest exporters of VW while Bihar, Kerala, Gujarat, Maharashtra, Jharkhand and Odisha are the frontline importers. The current state of inter-state VW trade is tending to aggravate scarcities in already water scarce states, with VW flowing from water scarce to water rich regions and in the direction opposite to the proposed physical transfers (Kampman et al., 2008; Verma et al., 2009). Instead of a prescription of water endowments, VW flows are influenced by several other factors such as per capita availability of arable land and more importantly by biases in food and agriculture policies of the Government of India like for e.g., procurement patterns of the Food Corporation of India. In order to have a comprehensive understanding of virtual water trade, non-water factors of production need to be taken into consideration.
Fig.3 Inter-state virtual water flows (109m3/yr) in India, as estimated by Kampman (2007)
Virtual water in Crop and Animal products
The VW content of animal products is far higher than that of crop products. Animals need to be fed and watered right through their lives. The total amount of real and VW consumed by animals and the water expended during processing are proportionately partitioned among the diverse animal products. This proportional allocation may also occur in terms of weight or more frequently, by using the market value. As per the estimates of Mekonnen and Hoekstra (2011) the ready-to-eat animal products have an estimated VW content of 3,000 to 15,000 litres/(kg product) of VW, as against about ~1,000 to 3,000 litres/(kg product) for ready-to-use crop products. As the VW content is significantly higher for cotton, coffee beans and cocoa beans, these plant products clearly stand apart as an exception.
Fig.3 Global average crop water consumptive use, m3/kg
The VW content of products strongly vary from place to place, and is strongly influenced by climate, level of technology in farming and consequent yield. The units used so far to express the VW content of various products are in terms of cubic meters of water/ ton of product. For example, global average VW content of rice (paddy) is 2291m3/ton while it is 1334m3/ton for wheat. VW content of (broken) rice in the shop is ~ 3420m3/ton. A consumer might be more interested in knowing how much water a product consumes per unit of consumption. Table 1 is the global average of VW for selected products.Tables 2, 3 and 4 depict the average VW in selected crop and animal products in India.
Table 1 Global average VW content of selected products per unit of product
|Product||VW, liter||Product||VW, liter|
|Black tea (250 ml)||35||Bread (30g)||40|
|Beer (250 ml)||75||Potato (100g)||25|
|Wine (125 ml)||120||Apple (100g)||70|
|Black coffee (125 ml)||140||Orange (100g)||50|
|Orange juice (250 ml)||170||Egg (40g)||135|
|Apple juice (250 ml)||190||Potato chips (200g)||185|
|Milk (200 ml)||200||Hamburger (150g)||2000|
Table 2 Average VW in some crop and animal products, India (Chapagain and Hoekstra, 2004)
|Category||VW (m3/ton)||Category||VW (m3/ton)|
|Sugar (refined)||1391||Leather (bovine)||17710|
Table 3 Average VW in some edible oils, India (Chapagain and Hoekstra,2004)
|Category||Virtual water content (m3/ton)|
Table 4 Average VW in crop products, India (Chapagain and Hoekstra,2004)
|Type||VW in (m3/ton)||Category||VW in (m3/ton)|
|Urad/ Mung Dal||3078||Grapefruit||411|
|Pepper||8333||Groundnut (in shell)||3420|
The question of ‘how much water one eats every day?’ might sound strange but true if paid some more thought. Estimates by the Water Footprint Network (WFN), show that the water needed in the production of industrial products one uses daily, such as paper, cotton and clothes, amounts to ~450 l d-1. WFN scientists determined that globally 92% of the water one use is invisible and embedded in their food. Research shows that an Italian eats nearly 5,600 litres each day; Brazilian 5,200 litres daily, an Indian 2700 litres and a US citizen consumes 6500 litres/day. Water expert Tony Allan warns: what we eat and what we do not waste will enable us to be globally water secure. Sensible food consumption and natural resource-aware trade should become two of the principal commandments for our 21st century society if we want to build a sustainable future. In light of the existing water scarcity and imbalances in water availability at globally and regionally, a sustainable virtual water trade is utmost important in bringing water use efficiency. A shift towards water conservation and water demand management is essential for the sustainability of water resources and the environment, as well as economic efficiency and social development.
Allan J A. 1994: Overall perspectives on countries and regions. In: Rogers, P. Lydon, P. (eds.): Water in the Arab world – Perspectives and prognoses. Harvard University Press, Cambridge
Allan J A. 1998. Virtual water: A strategic resource global solutions to regional deficits. Ground Water, 36: 545–546.
Allan J A. 2001. Virtual Water – Economically Invisible and Politically Silent: A Way to Solve Strategic Water Problems. International Water and Irrigation, 21(4): 39-41.
Allan J A. 2003. Virtual Water – the Water, Food, and Trade Nexus. Useful Concept or Misleading Metaphor? Water International, 28 (1): 106-113.
Allan T. 1993. Fortunately there are substitutes for water: otherwise our hydropolitical futures would be impossible. In Proceedings of the Conference on Priorities for Water Resources Allocation and Management. Southampton, U. K: Overseas Dev. Agency. 13–26 p.
Allan T. 2011. Virtual Water: Tackling the Threat to Our Planet’s Most Precious Resource. London: I. B. Tauris and Co. Ltd
Beadon E and Page T. 2010. UK’s ‘Virtual Water’ Reliance Leaves International Footprint. Royal Academy of Engineering Report. Retrieved from http://www.raeng.org.uk/news/releases/shownews.htm?NewsID=564
Chapagain A K. and Hoekstra A Y. 2003. Virtual water flows between nations in relation to trade in livestock and livestock products. Value of Water Research Report Series No. 13. Delft, the Netherlands: UNESCO-IHE.
Chapagain A K. and Hoekstra A Y. 2004. Water footprint of nations. Value of Water Research Report Series No. 16. The Netherlands: UNESCO-IHE, Delft.
Falkenmark M. and Rockström J. 2004. Balancing Water for Humans and Nature: The New Approach in Ecohydrology, Earthscan, London
FAO. 2010. FAOSTAT database, Food and Agriculture Organisation, Rome Available: http://faostat.fao.org
Hoekstra A Y and Hung P Q. 2005. Globalisation of water resources: International virtual water flows in relation to crop trade. Global Environmental Change, 15(1):45–56.
Hoekstra A Y and Chapagain A K. 2008. Globalization of Water: Sharing the Planet’s Freshwater Resources. Oxford, UK, Blackwell Publishing. 208pp.
Hoekstra A Y and Hung P Q. 2002. Virtual water trade: A quantification of virtual water flows between nations in relation to international crop trade. Value of Water Research Report Series No.11, IHE, Delft, the Netherlands.
Hoekstra A Y. 2003. Virtual water: An introduction. In Virtual water trade: Proceedings of the International Expert Meeting on Virtual Water Trade (Ed. Hoekstra, A.Y.). Value of Water Research Report Series No. 12. Delft, the Netherlands: UNESCO-IHE
Hoekstra A Y., Chapagain A K., Aldaya M M and Mekonnen M M. 2011. The water footprint assessment manual: Setting the global standard, Earthscan, London, UK. Available from: http://www.waterfootprint.org/downloads/TheWaterFootprintAssessmentManual.pdf
Kampman D A., Hoekstra A Y and Krol M S. 2008. The water footprint of India. Value of Water Research Report Series No 32, UNESCO-IHE, Delft, Netherlands
Kampman, D.A. 2007. Water footprint of India: A study on water use in relation to the consumption of agricultural goods in the Indian states. Masters’ thesis. Enschede: University of Twente.
Kumar V and Jain S K. 2007. Status of virtual water trade from India. Current Science, 93: 1093-1099.
Mekonnen M M and Hoekstra A Y. 2011. The green, blue and grey water footprint of crops and derived crop products. Hydrology and Earth System Sciences, 15: 1577–1600.
Reddy Y R K. 2005. ‘‘Time to promote virtual water measures.’’ The Financial Express, October 15, 2005.
Rost S., Gerten D., Bondeau A., Lucht W., Rohwer J. and Schaphoff S. 2008. Agricultural green and blue water consumption and its influence on the global water system. Water Resources Research, 44, W09405, doi:10.1029/2007WR006331.
Sharma S. 2003. ‘‘Stopping virtual water trade.’’ India Together. Retrieved from http://www.indiatogether.org/2003/sep/env-virtual.htm
Sivakumar S K. 2004. ‘‘It’s called ‘virtual water’…’’. The Hindu, June 6, 2004. Retrieved from http://www.hindu.com/thehindu/mag/2004/06/06/stories/2004060600150200.htm
Verma S., Kampman D A., Van der Zaag P and Hoekstra A Y. 2009. Going against the Flow: A Critical Analysis of Inter-State Virtual Water Trade in the Context of India’s National River Linking Program. Journal of Physics and Chemistry of the Earth. 34(4-5): 261–269.
Zimmer D. and Renault D. 2003. Virtual water in food production and global trade. In: Hoekstra, A.Y. (ed.): Virtual water trade. Proceedings of the International Expert Meeting on Virtual Water Trade, Value of Water Research Report Series 12, UNESCO-IHE Delft, The Netherlands, pp. 93-109.