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Virtual Water and Water Footprints
Compelling Notions, But Notably Flawed
Reaction to Two Articles Regarding the Virtual Water Concept. E.Gawel, K.Bernsen.
2011. GAIA 20/3: 162 –167; A.Biewald. 2011. GAIA 20/3: 168 –170
Virtual Water and Water Footprints. Compelling Notions, But Notably Flawed
GAIA 20/3 (2011): 171–175 | Keywords: economics, international trade, livelihoods, policy
he notions of virtual water and water footprints appear frequently in the popular literature and also in scholarly journals. Many authors describe the “flows of virtual water” around
the planet in the form of internationally traded goods and services. Some authors calculate the national “water savings” or “water losses” that occur through “virtual water trade” (Oki and Kanae 2004, Chapagain et al. 2006a, Hoekstra and Chapagain 2007,
Mekonnen and Hoekstra 2010), while others assign responsibility for environmental degradation in one country to residents of
the importers of that country’s agricultural exports (Chapagain
et al. 2006 b, Van Oel et al. 2009). Often the importers are located
thousands of miles away. A natural extension of the virtual water literature has been the calculation of internal and external water footprints. Some authors suggest these provide useful insight
regarding the impacts of consumers in one country on the water resources of another.
While water can be viewed as an international resource, particularly in areas where countries share rivers, aquifers, and watersheds, water scarcity is largely a local and regional phenomenon.
Water scarcity arises when the demands on local and regional
resources exceed the available supply. While acknowledging important issues regarding transboundary resources, generally
there is little relationship between water consumption in
one region and water scarcity in another. For example,
changes in water consumption habits in New York will
have little impact, if any, on water scarcity conditions
in Beijing. Comparing or summing the water footprints of consumers in each city provides no helpful insight regarding the causes of water scarcity
or the policies that might be implemented to improve resource management in either location.
It is not helpful to suggest that consumers in
New York are consuming an unfair portion of
the world’s water resources simply because
their per capita water footprint exceeds
that of the residents of Beijing or any
other city.
T
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Dennis Wichelns
The Notions Do Not Enhance Understanding
Erik Gawel and Kristina Bernsen describe some of these issues
in their discussion of virtual water and water footprints (Gawel
and Bernsen 2011, in this issue). In particular, they note correctly that virtual water trade is not consistent with the concept of
comparative advantage and, hence, it should not be used to determine trading strategies or develop policy tools, such as waterbased tariffs, quotas, or tradable water permits. Such programs
would only be distortive, and they would not address other more
important issues that lead to inefficient allocation and use of
scarce resources.
Gawel and Bernsen also note that comparisons of water footprints across individuals or countries are not helpful, as water
footprints contain no information about water scarcity or prices
and availability of other resources that influence resource use decisions. In sum, they conclude that the frequently assumed policy implications put forth by those who calculate virtual water
flows and water footprints should not be adopted by those responsible for crafting national policies pertaining to international trade or environmental management. The authors raise important issues that the readers of the virtual water and water footprint
literature should consider before adopting those perspectives and
implementing the connoted policy prescriptions. If there is a flaw
in their presentation, it is perhaps their acknowledgment of the
notion of virtual water trade, although the authors show its limited suitability.
Countries trade goods and services according to their comparative advantages and other strategic and economic consider-
Contact: Dr. Dennis Wichelns | International Water Management
Institute | P.O. Box 2075 | Colombo | Sri Lanka |
Tel.: +94 11 2880000 | E-Mail: [email protected]
© 2011 D. Wichelns; licensee oekom verlag. This is an Open Access article
distributed under the terms of the Creative Commons Attribution License
(http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
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ations. There is no conceptual or empirical basis for suggesting
that water scarcity determines trading strategies or the flows of
goods and services between countries. Surely, many arid countries import agricultural goods, but the primary reason is an inadequate supply of arable land. Many humid countries, such as
Japan, Korea, and Singapore also import large amounts of agricultural products, as they have limited supplies of arable land per
capita (Wichelns 2010a, 2010b). In addition, those countries have
chosen to develop highly successful industrialized economies,
while importing many agricultural goods from elsewhere.
Empirical research has found no correlation between national water endowments and international trading patterns (de Fraiture et al. 2004). This should not be surprising, as water is not
exchanged in the trade of goods and services. Characterizing international trade as an activity driven by endowments of a single
input will not improve understanding of policy issues involving
trade or the impacts of trade policies on citizens of importing and
exporting countries. Given that countries do not engage in virtual water trade, we might encourage more appropriate analysis and
enhance policy discussions, by discontinuing the use of that inaccurate phrase.
Water is a scarce resource in many regions in the world, but there is little
relationship between water consumption in one region and water scarcity
in another. Thus, is virtual water trade the right concept to encounter the
problem?
Too Flawed to Rehabilitate
Anne Biewald has an alternative perspective, as she endeavors
to rehabilitate the concept of virtual water trade (Biewald 2011,
in this issue). She suggests that while the conclusions put forth
in some of the papers on virtual water and water footprints might
be misleading, the concept can be helpful when used correctly.
Furthermore, she proposes that notable clarity is needed when
defining virtual water and water footprints, as the notions are
related but dissimilar, and she embeds her definitions in a list
of three applications of virtual water analysis:
1. virtual water can be used to calculate how much water is
saved through trade (globally, nationally, and locally),
2. virtual water can be used to calculate water footprints for
individuals and countries, and
3. it can be used to calculate virtual water trade balances.
According to Biewald the first two applications are different from
the third. Only the third contains information about the source
of the virtual water; information that is needed to assess the sustainability of water use in a region. She suggests that because
Gawel and Bernsen have overlooked the distinction between the
concept of virtual water and its applications, they were not able
to appreciate the advantages inherent in knowing and accounting for the sources of virtual water traded in goods and services.
© Brigitte Hiss/Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit
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Given this perspective, Biewald ignores the first two applications and focuses her discussion on the third one. But it is useful to consider briefly those two items. In much of the published
literature on virtual water and water footprints, the authors present calculations of the water saved or lost through international
trade (application 1), and they calculate water footprints for individuals and countries (application 2).
Estimates of the water saved or lost through international
trade in goods and services are inappropriate and misleading.
Water is one of many inputs in production and, while scarce in
many locations, water does not alone determine trade strategies
or subsequent trading patterns. Countries do not import or export water resources and, thus, they do not gain or lose water in
the process of conducting international trade. Estimates of national water savings and losses can misinform citizens and mislead public officials responsible for choosing smart policy options. It is not helpful to suggest that some countries save more
water than they have, through the conduct of international trade,
or that some countries lose substantial volumes of water by exporting goods in industries that generate employment and enhance livelihood opportunities. Yet this is precisely what several
authors suggest in their analyses (Chapagain et al. 2006a, Chapagain and Hoekstra 2008, Mekonnen and Hoekstra 2010).
Water Footprints vs. Carbon / Ecology Footprints
Water footprints seem compelling at first glance, the term reminding us of ecological and carbon footprints (Hoekstra 2009).
Yet the analogy between those notions is not complete (see Gawel and Bernsen 2011). Ecological and carbon footprints attempt
to describe the global implication of human activities in any local or regional setting (Moran et al. 2008, Kitzes and Wackernagel 2009, Peters 2010). Economic activities place demands on the
planet’s productive and assimilative capacity (ecological footprints), while releasing waste materials that modify and degrade
the atmosphere (carbon footprints). In each case, the activities
generate impacts that can be summed and compared in a meaningful fashion across locations. For example, the carbon emitted
by automobiles in New York has the same impact on the atmosphere as the carbon emitted by autos in Beijing. Hence, there
is some logic in comparing and summing the carbon footprints
of residents in those cities.
In fact, a reduction in carbon footprints in any country will
reduce global pressure on the atmosphere. The same is not true
of water footprints. Residents of humid countries might have
rather large water footprints, particularly when compared with
those of residents in arid countries. Yet those large water footprints might be perfectly sustainable and they might impose no
harm on the environment. There might be no social gain from
efforts to reduce water footprints in such settings. Rather, there
might be social losses if such efforts reduce the demand for goods
and services in industries that provide gainful employment, enhance livelihoods, or contribute to international trade.
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There is no such thing as virtual water trade
and, thus, nothing can increase its usefulness
in describing how the world works.
Ecological footprints can be calculated for individuals, communities, and countries. The notion motivating ecological footprint analysis is that the earth’s productive potential is limited.
If the demands we place on the earth through our production
and consumption activities exceed the planet’s productive and
assimilative capacity, sustainability will not be achieved. Those
who estimate ecological footprints express the demands and
supply of productive and assimilative capacity in terms of a common metric, to enable summation and comparison of footprints
across regions and countries (Wackernagel 2009). In particular,
the authors express demand and supply in terms of “global hectares”, which are intended to reflect the areas of land and sea required to support production and consumption activities and
assimilate waste materials. The estimates of global hectares are
used for two purposes: 1. to compare the demand pressures imposed by individuals and communities, 2. to determine if the sum
of demand pressures is greater than the available supply of the
earth’s productive and assimilative capacity.
Some authors (Kestemont et al. 2011, Moran et al. 2008) have
shown that the ecological footprints of residents in wealthy countries exceed those of residents in poor countries. Others (Ewing
et al. 2010) have assessed that the sum of ecological footprints
has been greater than earth’s capacity since the middle-1970s,
and the gap between the aggregate ecological footprint and the
earth’s capacity is increasing. Such analyses, if accurate and appropriate, would provide guidance regarding whether or not the
global population is using the earth’s resources in a sustainable
manner. In addition, the analysis enables one to examine opportunities for reducing global demand pressures, by noting regions
in which the ecological footprints are substantially higher than
productive capacity. In theory, reducing an ecological footprint
in one region will contribute to reducing the sum of ecological
footprints across regions or countries.
The comparison and summary properties of ecological footprints are not shared by water footprints for two reasons: 1. water scarcity issues, which involve the imbalance between supply
and demand, are regional and local, rather than international,
and 2. estimates of water footprints contain no information describing impacts. It is reasonable to expect that the water footprints of consumption and production activities in humid countries will be larger than those in arid countries, all else equal.
One might expect the water footprint of banana production to
be greater in Sri Lanka than in Jordan. Yet the higher water footprints might not be causing any harm to local residents or the
international community. Reducing the water footprints of residents in Amsterdam will not improve water availability in Amman. Comparing or summing the water footprints of consumers
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in both cities will not provide policy-relevant information. The
notion of a water footprint is simply too myopic to guide public
officials toward appropriate policies.
Turning now to application 3, Biewald suggests that the most
important information regarding the source of virtual water is
the distinction between blue water (surface water and groundwater) and green water (rainfall stored as soil moisture). She states
that countries importing crops or food products as a replacement
for domestic, rainfed production would not actually save any water, as rainfall would be consumed by native vegetation on lands
that are not farmed. By contrast, countries importing crops or
food products to replace irrigated production would save water,
as there would be smaller diversions of surface water and less
abstraction of groundwater for irrigation. Only by considering
green and blue water sources one can determine the “problematic or positive effects of virtual water trade” (p. 169).
Are the Terms “Green” and “Blue Water” Helpful?
Adding the notions of green and blue water to the notions of virtual water and water footprints does not improve clarity or enhance policy relevance. Green and blue water are not scientifically sound categories of water resources, and they are not necessarily distinct. Rainfall stored as soil moisture (green water) can be
displaced into groundwater (blue water) by subsequent rainfall
events, and groundwater can interact with stream flows (blue water). No author in the virtual water and water footprint literature
has demonstrated any conceptual or empirical basis for the perspective they offer regarding the preference for “saving” blue water in favor of “saving” green water (Yang et al. 2006, p. 450, Yang
and Zehnder 2007, Aldaya et al. 2010).
The basis for the suggestion that “blue water used for irrigation is the part of the virtual water that is responsible for local
water scarcity” (Biewald 2011, p. 170) is not apparent. The intent
of the statement also is unclear, as water scarcity is a function
of supply and demand. Water is certainly quite scarce in many
areas where farmers and others rely completely on rainfall, while
it is not scarce in many humid regions where the amount of water available exceeds the sum of individual demands. Water scarcity in many arid and semi-arid regions has motivated farmers
and governments to construct irrigation projects and to develop
water supplies for agriculture and other uses.
Competing demands for water have changed, over time, in
many irrigated areas, as populations have expanded and incomes
have increased. A casual observer might suggest that water seems
particularly scarce in areas where surface water and groundwater are used for irrigation, but that would not describe the full story. Water scarcity likely has intensified as the sum of competing
demands has grown larger than the available supply. Policy intervention and technical solutions are needed to address the scarcity situation.Water users and public officials will benefit by taking
a broader, more informed perspective regarding the evolution of
water scarcity issues in both rainfed and irrigated settings.
Is Trade to Blame for Inappropriate Water
Management?
Most international trade enhances production and consumption
opportunities, and is not conducted to replace selected forms of
economic activities. In water-scarce regions, water resources will
be fully allocated and utilized in activities determined by consumers, firms, and regulatory authorities. Countries generally do not
seek to replace agricultural production by importing crop and
livestock products. Trade strategies and patterns evolve, as time
passes, in response to many economic and political stimuli. The
attempt to characterize international trade as an endeavor to reduce the extent of irrigated agriculture in the interest of saving
blue water resources is not pertinent.
Biewald suggests that scientific analysis should focus on water-scarce regions, in which virtual water is exported, as it is here
that virtual water trade can aggravate water scarcity and worsen
local living conditions. This suggests that international trade is
somehow responsible for regional water scarcity issues.Yet much
of the unsustainable use of water in water-scarce regions occurs
in the production of crops and livestock products consumed by
households or sold in domestic markets. Indeed, hundreds of millions of small-scale farmers depend on agriculture for their livelihoods, and many of those farmers use groundwater or surface
water at aggregate rates that are not sustainable. However, most
of the rice and wheat produced on the Indo-Gangetic Plain are
consumed in India and Pakistan, just as most of the maize produced on the North China Plain is consumed within China.
The unsustainable use of water in China, India, and Pakistan
is a critically important policy issue, which cannot be addressed
successfully by attempting to characterize the problem as a consequence of virtual water trade. International markets certainly
influence prices and marketing opportunities observed in many
regions. Yet firm-level and consumer decisions regarding water
use – and the policies that influence those decisions – are made
within regional settings. Estimates of virtual water trade will not
improve understanding of how regional water scarcity problems
arise, or how public officials should intervene to prevent further
degradation of resources and livelihood opportunities.
Biewald wants to give virtual water a chance, as the notion has
appeared in the literature only since 1996. One might suggest,
alternatively, that 15 years is a long time in which the notion has
provided very little understanding of water resource issues and
no helpful policy guidance. During that time, many authors have
added compelling components to virtual water analysis, such as
water footprints, blue, green, and gray water, internal and external water footprints (Chapagain and Hoekstra 2007, Dabrowski
et al. 2009). Many have also sought to estimate the virtual water
contents of an increasingly wide array of goods and services (Kumar and Jain 2007, Aldaya and Hoekstra 2010). Others have estimated water footprints with increasing levels of detail, and they
have extended their analyses to include internal and external footprints involving a wide range of countries (Ma et al. 2006, Guan
and Hubacek 2007, Chapagain and Hoekstra 2008, Van Oel et al.
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2009). Such efforts should provide more useful analytical tools,
but such an outcome is unlikely, given the inherently myopic nature of water footprints and the lack of any basis for describing
international trade in terms of a single input.
Moving Forward in Smarter Fashion
While the notions of virtual water and water footprints have
gained the attention of many water resource scholars and practitioners, they lack a legitimate conceptual foundation. There is
no such thing as virtual water trade and, thus, no effort to embellish the notion can increase its usefulness in describing how the
world works. Firms and countries engage in trade for many reasons that lie outside the dimension of a single resource perspective. Even in water-scarce areas, residents and public officials
might be more concerned with energy resources, land, other inputs, and the implications of resource allocation and use on livelihoods. Attempting to describe inherently complex production
and trading activities with notions based on a single resource
can be misleading and potentially harmful.
In sum, virtual water and water footprints will not be helpful
in enhancing understanding of water issues or in crafting smart
policies to improve resource use and livelihoods. Rather than investing additional scholarly effort in embellishing these notably
myopic notions, we should return to the scientific concepts and
terminology that have guided our analysis and discussion of complex issues involving agronomy, hydrology, and the social sciences for centuries. If the ultimate goal of science is to improve the
human condition as broadly and deeply as possible – a goal that
embeds the notions of sustainability and growth –, then we need
to leave behind the fanciful notions of virtual water and water
footprints, without delay.
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Submitted May 17, 2011; revised version
accepted July 2, 2011.
Dennis Wichelns
Born 1960 in Jasper, Wyoming, USA. Deputy
Director General and Senior Fellow with the
International Water Management Institute.
Research fields: agricultural, natural resource, and
environmental economics. Project areas: South and
Southeast Asia, Central Asia, sub-Saharan Africa. Specialties:
water economics and policy, irrigation, food security.
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