Hydrology and Earth System Sciences
www.hydrol-earth-syst-sci.net
1027-5606
1607-7938
10
3
2006
10.5194/hess-10-455-2006
http://www.hydrol-earth-syst-sci.net/10/455/2006/
http://www.hydrol-earth-syst-sci.net/10/455/2006/hess-10-455-2006.html
http://www.hydrol-earth-syst-sci.net/10/455/2006/hess-10-455-2006.pdf
455
468
2006-06-30
Water saving through international trade of agricultural products
A. K. Chapagain
A. Y. Hoekstra
a.y.hoekstra@utwente.nl
H. H. G. Savenije
UNESCO-IHE Institute for Water Education, Delft, The Netherlands
Group of Water Engineering and Management, Faculty of Engineering Technology, University of Twente, Enschede, The Netherlands
Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands
Many nations save domestic water resources by importing water-intensive
products and exporting commodities that are less water intensive. National
water saving through the import of a product can imply saving water at a
global level if the flow is from sites with high to sites with low water
productivity. The paper analyses the consequences of international virtual
water flows on the global and national water budgets. The assessment shows
that the total amount of water that would have been required in the
importing countries if all imported agricultural products would have been
produced domestically is 1605 Gm<sup>3</sup>/yr. These products are however being
produced with only 1253 Gm<sup>3</sup>/yr in the exporting countries, saving
global water resources by 352 Gm<sup>3</sup>/yr. This saving is 28 per cent of the
international virtual water flows related to the trade of agricultural
products and 6 per cent of the global water use in agriculture. National
policy makers are however not interested in global water savings but in the
status of national water resources. Egypt imports wheat and in doing so
saves 3.6 Gm<sup>3</sup>/yr of its national water resources. Water use for
producing export commodities can be beneficial, as for instance in Cote
d'Ivoire, Ghana and Brazil, where the use of green water resources (mainly
through rain-fed agriculture) for the production of stimulant crops for
export has a positive economic impact on the national economy. However,
export of 28 Gm<sup>3</sup>/yr of national water from Thailand related to rice
export is at the cost of additional pressure on its blue water resources.
Importing a product which has a relatively high ratio of green to blue
virtual water content saves global blue water resources that generally have
a higher opportunity cost than green water.
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