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Georgina Smith/CIAT.

The great water footprint connundra

Compelling discussion, commentary, stories on agriculture within thriving ecosystems.

Is a small footprint really better than a large one?

In light of World Day to Combat Desertification, Dennis Wichelns, former IWMI Deputy Director General and current visiting professor at the Institute of Water Policy, Lee Kuan Yew School of Public Policy, National University of Singapore, discusses the usefulness (or lack thereof) of using water footprints to mitigate water scarcity issues.

Water footprints measure the amount of water consumed or applied in the production of a good or service.  A single cup of coffee, for example, has a water foot print of 140 liters of water.  The concept is widely publicized and is now beginning to influence government policy. But according Dennis Wichelns, professor at the Institute of Water Policy National University of Singapore, that is a mistake. The problem, he argues, is that this measure looks only at the water input for particular products, and takes no account of other factors that may be more relevant to sustainable resource use. In a humid regions with lots of rainfall, for instance, the water footprint of an activity might not matter at all.

Interview conducted by James Clarke, Head of Communications at the International Water Management Institute and Abby Waldorf, Communications and Engagement Fellow of the CGIAR Research Program on Water, Land and Ecosystems.


Hello Martin,

Thank you for your thoughts regarding the water footprint discussion. I appreciate your interest in the topic.

You are correct, of course, in suggesting that international trade is complex. Indeed, the decisions of firms and countries regarding trade involve quite a bit of economics, politics, and cultural considerations. Yet they do not include much - if any - consideration by importers of the inputs used to produce goods and services in the countries of origin. Importing countries do not import the water used to produce the goods they purchase. Depicting international trade as if it involves the movement of "virtual water flows" has no basis in theory or in empirical observations.

Countries in the Middle East import substantial amounts of grain because they lack the resources to produce sufficient grain on their own. The importing countries likely care quite a bit about the price, quality, and availability of grain in international markets. Yet they have little reason to care about the inputs used to produce the grain in any of the exporting countries. Importers need to find reliable exporters who provide commodities of suitable quality at reasonable prices. They do not need to know how much water, energy, or labor is used to produce the commodities.

Many observers have proposed the perspective that countries somehow import the "virtual water embedded" in grains obtained through international trade. Yet that is simply not the case. There is no such thing as water embedded in traded commodities. It might be interesting to consider that large volumes of water are required to produce the wheat that Egypt imports or the cotton that Central Asia exports. Large amounts of energy, labor, chemicals, and machinery also are involved in crop production. Yet none of those inputs moves across an international border when countries trade in wheat and cotton. There is no such thing as "virtual water trade" or the virtual trade in any productive input.

I suppose the notions of virtual water and water footprints are appealing to many observers because they generate compelling images of large volumes of water moving across the globe on the wings and in the shipping lanes of international trade. When the colors of green and blue are added to the picture, the images become even more compelling. Yet the notions of virtual water and water footprints are just that - notions. They are not concepts or established facts. They are not the outcome of scientific inquiry. They cannot explain international trade and they have no place in policies or agreements pertaining to international trade.

Quite a bit of time and effort have been invested in recent years in calculating water footprints and estimating virtual water flows. Yet most of the published reports and journal articles provide no insight regarding why or how countries engage in trade. The sooner we leave behind the notions of virtual water and water footprints, the sooner we can return to conducting science-based studies that truly enhance understanding of the complex subjects that require and deserve our very best scholarly efforts.

Best regards,

Dennis Wichelns

Dear Dr Wichelns,

The water footprints reveal immensely important knowledge on the dependence of water imports and thus political dependence. As it is well-known, agricultural trade like wheat for example is highly political. VW and the WF can and do serve as a tool in foreign-policy decision-making of trade dependent countries to diversify their portfolio. Unfortunately, you do not even take the political factors into account.

The label you attach to the WF as 'meaningless' is highly uninformed. You only throw a very thin slice of the cake to the general audience but fail to even acknowledge that there are other factors to consider. Using 'society' as a reference point is somewhat comical because you do not specify the geographical origin. For example, a society like Yemen or Saudi Arabia has very little problems to provide pesticides, fertilizers, labour, farm equipment and even capital. However, both economies lack water resources to match food production with population growth. Agricultural trade informs us to what extent the two economies depend on which countries to import food. This often coincides with politically motivated food aid shipments, preferential trade agreements. The WFs can serve as a formidable tool to escape from political coercion by diversifying the portfolio of food imports using the vw/wf argument.

I often wish you would take on other indicators such as GDP forecasts in a similar way. Governments across the world plan their budgets according to possibly indicative numbers suggested by their economic planning departments.



I see the problem that the assessment of the water footprint (WF) is being only looked from one side (the number), not taking into account the whole picture, like this miscommunicating. If you look at the global standards defined in “The Water Footprint Assessment Manual” https://www.waterfootprint.org/?page=files/WaterFootprintAssessmentManual, you will see that for a WF assessment also a sustainability assessment (from an environmental, social and economic point of view) has to be conducted, as well as responses formulated.
Why should a product be produced with more water than actually necessary? Would it be not reasonable to allocate the super flus water consumption to other uses?
Are any countries considering the WF as a policy tool? Spain has already implemented WF assessment in their river basin legislation and beside India, the Netherlands is also taking it into consideration.
One of the big benefits from the WF is that it takes the water balance into account, which in previous water use measures was not considered.
In my opinion, people should first inform themselves properly, before discussing!!!!

Hello Nicolas,

Thank you very much for your comment and perspectives. I appreciate your interest in the topic of water footprints.

In your comment you raise the question of why a product should be produced with more water than is necessary. You suggest also that any excess water could be allocated to other uses. While these statements seem appealing at first glance, the issues usually are a bit more complex than your statements indicate. Generally, there is not a single volume of water that represents the amount "actually necessary" to produce a good or service. Water is one input, among many. Producers must evaluate the incremental costs and gains from each input, while considering interactions between inputs. For example, water, nutrients, and pesticides interact in complex ways in the production of crops. Higher yields generally require greater use of inputs. One might wish to reduce the amount of water applied to a crop field, but that effort might require more energy (in the form of implementing drip or sprinkler irrigation) or more labor (in the form of more intensive water management), and it might result in a yield reduction. Society also might be concerned about the relative, incremental impacts and opportunity costs of inputs such as water, energy, nutrients, pesticides, and machinery. It is not sufficient or helpful at the farm-level, or from society's perspective, to focus on just one input, even one as important as water.

You are right that Spain has called for the use of water footprints in assessing water management in river basins. Water footprints seem compelling to many policy makers. Yet, Spain's interest does not demonstrate that water footprints are appropriate or helpful. I describe some of the policy shortcomings of the water footprint approach, with particular emphasis on Spain, in the following review essay:

Wichelns, D., 2010. Virtual Water and Water Footprints: Policy Relevant or Simply Descriptive? Review Essay: Garrido, A., Llamas, M.R., Varela-Ortega, C., Novo, P., Rodríguez-Casado, R., Aldaya, M.M., 2010. Water Footprint and Virtual Water Trade in Spain: Policy Implications (New York, Springer). Intl. Journal of Water Resources Development, 26(4), 689-695.

You suggest correctly also that the Netherlands is considering the use of water footprints. In fact, the Netherlands Environmental Assessment Agency published a report very recently, in which they conclude the following:

"The water footprint indicator has been effectively used as a wake-up call to raise awareness among the general public, businesses and governments about the global scale of water appropriation. Even so, as these water volumes hardly reflect environmental impact, the water footprint indicator is unsuitable to be used for goal-setting, policy-making, monitoring and evaluation, in relation to sustainability."

The full report of the Netherlands Environmental Assessment Agency is available at: www.waterfootprint.org/Reports/Witmer-Cleij-2012.pdf.

You mention in your comments that the Water Footprint Assessment Manual calls for environmental, social, and economic analysis to complement the calculation of water footprints. Certainly, those aspects are important. Yet, they cannot be analyzed and evaluated as easily or as quickly as water footprints can be calculated. Thus, while many authors call for deeper analysis, they do not provide it. They simply publish estimates of water footprints of one or more agricultural or industrial activities. I have critiqued the Water Footprint Assessment Manual in the following article:

Wichelns, D., 2011. Assessing Water Footprints Will Not Be Helpful in Improving Water Management or Ensuring Food Security. Review Essay: Hoekstra, A.Y., Chapagain, A.K., Aldaya, M.M., Mekonnen, M., 2011. The Water Footprint Assessment Manual: Setting the Global Standard (London, Earthscan). Intl. Journal of Water Resources Development, 27(3), 607-619.

You suggest also that water footprints take water balance into account, and that earlier measures of water use have not done this. I am not sure this is the case. Water footprints simply are estimates of the amount of water used in production and processing. Most - if not all - of the estimated water footprints do not include any information pertaining to water balance. By contrast, numerous reports and journal articles have examined water balance using well-established and time-tested concepts that are well-founded in the science of hydrology and water management. The International Water Management Institute (www.iwmi.org) is a very good source of articles and reports describing water balance calculations.

Perhaps more importantly, no estimates of water footprints contain any information regarding the opportunity cost or scarcity value of water used in production and processing. Such information is critically important in determining the optimal allocation and use of water resources. Lacking such information, we cannot use water footprints to determine appropriate policies or strategies regarding water management.

Thank you again for your thoughtful comments.

Supporters of the usefulness of WFs might also read "Water Footprints: Path to enlightenment or false trail", Ag Water Management, 134, 2014. https://dx.doi.org/10.1016/j.agwat.2013.12.004

Dennis Wichelns analyses are (to me) persuasive in demolishing the usefulness of WFs as a policy guide; my paper adds the further dimension of showing how technically flawed the computational analysis typically is. ET is assumed to be at potential levels; no allowance is made for the ET that would naturally occur in the absence of the crop being assessed. For much of Europe, WFs are actually NEGATIVE -- because the alternative natural vegetation would consume more water than the agricultural crop. the much publicised flooding in the west of England last year was in part blamed on the conversion of woodlands into arable farmland, precisely indication that the crops grown in this areas have a negative footprint.
Tony Allan's original insight that countries make up for severe water deficits by importing "virtual water" was a helpful insight. The subsequent industry of computing tomes of numbers that are (a) wrong and (b) meaningless in policy terms has added nothing further.