Virtual Water in the Real World


Globalization of Water: Sharing the Planet's Water Resources . Hoekstra, A. Y., and A. K. Chapagain . 2008 . Blackwell Publishing , Malden , MA . 220 (xii + 208) pp. $65.00 (hardcover) . ISBN978-1-4051-6335-4 .

Arjen Hoekstra, Ashok Chapagain, and others in their research team have, since 2001, made very important contributions to the development of the science associated with the concepts of “virtual water use” and “virtual water trade” and in the related concept of “water footprints.” Their modeling of these concepts and the national and global processes associated with them have been even more important. They first worked together at the UN Educational Scientific and Cultural Organization-IHE (UNESCO-IHE) Institute for Water Education in Delft in the Netherlands. Arjen Hoekstra now leads an internationally recognized research group working on water footprints at the University of Twente in the Netherlands. Ashok Chapagain is making an extremely important contribution at World Wildlife Fund–UK, where he is underpinning the water science of this influential international organization. The authors have marshaled an immense knowledge of water resources management and the essential capacities to model the complex synergies of water, food, and other commodity trade. Their work has contributed fundamentally to the development of the concepts of virtual water and virtual water trade. They have also promoted and widely disseminated the idea of the water footprint.

The purpose of the book is first to identify and quantify the volumes of water needed to produce food and industrial commodities. Second, it provides estimates of the impact of the degradation of the quality of water put back into the water environment after crop production and industrial manufacturing have taken place. By calculating the water footprints of the agricultural and industrial activities of the national economies of the world, the authors have highlighted the small number of economies that have water surpluses and the vast majority of economies that are dependent on imports of virtual water in food and industrial commodities.

The authors expertly introduce newcomers to the history of the concepts and the associated and sometimes controversial economic theory. They make understandable complex issues such as defining the water content on the basis of how much water is used to produce commodities at the place of production. They also emphasize the different volumes of water associated with the production of the same commodities in importing economies. The assumptions and methods are clearly stated.

Another important contribution of the book is that it provides a way of gaining a more comprehensive and realistic definition of water resource use. By including green water or soil water among the contributing water sources in rain-fed agricultural activitiesthe authors also have advanced our grasp of the water budgets of nations. They achieve this mode of analysis by estimating water use in agriculture on the basis of evapotranspiration. Another important methodological contribution is their attempt to estimate the impact of water use on stores of surface and groundwater and on flows to which water is returned after use. These impacts are shown to be particularly high for manufacturing industries.

The book is well illustrated with diagrams and maps that will help readers new to the field grasp the theory and especially the national-level and global processes being analyzed. A number of case studies are used to highlight the insights and understanding provided by the methods and analysis. Very useful tables also allow the reader to see, for example, that there are less than 10 economies worldwide that have a significant water surplus, but that these economies have successfully met, or have the potential to meet, the water deficits of the other 190 economies. Another chapter shows that an unintended, but very useful, outcome of virtual water trade in the crop and livestock sector has been very significant water savings at the global scale. The authors estimate that 1250 billion m3 of water—calculated on the basis of conditions in producing economies—is associated annually with international crop and livestock trade. If these commodities were to be produced in the importing countries, the volume of water needed would be 1600 billion m3. This means that the water, food, and trade nexus has enabled 350 billion m3 of water to be “saved.” That is enough water to provide for the needs of about 300 million people with the average water global footprint of 1250 m3/year. The population of the Middle East and North Africa is about 300 million, as is that of the United States although, as the study shows, the water footprint of an American is almost exactly twice the world average. Three hundred million is equivalent to half the population of Africa.

Another chapter highlights the capacity of virtual water and water footprints to reveal the questionable economics of existing and planned policies to achieve water security. Their analysis shows that in China, the water-scarce region of northern China is a net exporter of virtual water to the water-surplus region of southern China. The current policy remedy is to move water from the south to the north. The very useful capacity of the virtual-water and water-footprint concepts to highlight underlying economic and hydrological fundamentals does not, however, mean that societies and political processes welcome the revelations. The most powerful features of virtual water trade are its economic invisibility and political silence. Consumers enjoy the delusion of food and water security provided by virtual water trade. Neither consumers nor politicians have willingly adopted the new virtual water and water footprint mindset that would require them to recognize their water and food insecurities. These issues are politically toxic and best kept off the agenda.

The science of this book is sound. It introduces new ideas and a very innovative analysis accessibly and persuasively. The concepts of virtual water and water footprints have taken some time to gain acceptance. This study will accelerate their adoption in the worlds of water science, water resource planning and allocation, and in places where the uses of water resources are highly politicized. It provides an inspired introduction for newcomers to the subject.