Saving water through global trade
Ashok K. Chapagain
Abstract
Many nations save domestic water resources by importing water-intensive products and exporting commodities\nthat are less water intensive. National water saving through the import of a product can imply saving water at a\nglobal level if the flow is from sites with high to sites with low water productivity. The report analyses the\nconsequences of international virtual water flows on the global and national water budgets. The assessment\nshows that the total amount of water that would have been required in the importing countries if all imported\nagricultural products would have been produced domestically is 1605 Gm3/yr. These products are however being\nproduced with only 1253 Gm3/yr in the exporting countries, saving global water resources by 352 Gm3/yr. This\nsaving is 28 per cent of the international virtual water flows related to the trade of agricultural products and 6 per\ncent of the global water use in agriculture. National policy makers are however not interested in global water\nsavings but in the status of national water resources. Egypt imports wheat and in doing so saves 3.6 Gm3/yr of its\nnational water resources. Water use for producing export commodities can be beneficial, as for instance in Cote\nd’Ivoire, Ghana and Brazil, where the use of green water resources (mainly through rain-fed agriculture) for the\nproduction of stimulant crops for export has a positive economic impact on the national economy. However,\nexport of 28 Gm3/yr of national water from Thailand related to rice export is at the cost of additional pressure on\nits blue water resources. Importing a product which has a relatively high ratio of green to blue virtual water\ncontent saves global blue water resources that generally have a higher opportunity cost than green water.