22nd September

International trade has major impact on 'water frootprint'

A study by the Water Footprint Network (WFN) analysing the quantity and distribution of global water use (1996-2005), calculates the water footprints of individual countries based on their production and consumption, and uses visually-striking graphics to display the pathways of the world’s largest virtual water movements.

First introduced in 2002 at the University of Twente in the Netherlands, the water footprint concept is a measure of ecological impact comparable to the better-known carbon footprint but focusing on freshwater.



Virtual water balance per country related to trade in agricultural and industrial products over the period 1996-2005. Net exporters are shown in green and net importers in red. The arrows show the biggest gross international virtual water flows (> 15 Gm3/yr); the fatter the arrow, the bigger the virtual water flow. Source: Mekonnen and Hoeksrta, 2011.

WFN is a not-for-profit foundation under Dutch law whose stated aim is ‘To promote the transition towards sustainable, fair and efficient use of freshwater resources worldwide by advancing the concept of the water footprint as an explicit indicator of the direct and indirect use of water by consumers and producers.’

It also seeks ‘to increase awareness and understanding’ of how the consumption of goods and services and production chains relate to water, and impact on freshwater systems globally.

According to the WFN, the water footprint represents the total volume of freshwater used to produce the commodities, goods and services consumed by an individual, company or nation. It may be calculated for any product or well-defined group of consumers or producers, public organisation, private enterprise or economic sector and used as a geographically explicit indicator, not only showing volumes of water use and pollution, but also locations.

This study goes further than previous reports by the WFM in explaining global water movements by breaking down the different ways we use water to show the three components of the water footprint:

  • volume of rainwater consumed (green)
  •  volume of ground and surface water depleted (blue), and
  • the volume of freshwater required to assimilate the pollution load based on current water quality standards (grey)

As for virtual water – sometimes referred to as embedded or hidden water – the study notes that international virtual water flows in relation to trade in agriculture and industrial products averaged 2,320 billion m3 per year in the decade 1996 to 2005.

It lists the major gross virtual water exporters as the USA, China, India, Brazil, Argentina, Canada, Australia, Indonesia, France and Germany.
And it finds that the USA, Japan, Germany, China, Italy, Mexico, France, the UK and the Netherlands are the main importers of gross virtual water. .

Global water footprint
With these findings the study argues that for water-scarce countries it can sometimes be attractive to import virtual water thus relieving the pressure on the domestic water resources.

This happens for example in Mediterranean countries, the Middle East and Mexico. Also Northern European countries import a lot of water in virtual form (more than they export), but this is not driven by water scarcity. International trade patterns can only be understood from a multitude of factors; water scarcity is merely one of them,’ the study declares.

Significantly, the study points out that between 1996 and 2005, 20% of the global water footprint did not relate to domestic consumption but to export. And it finds that global savings from international trade in agricultural products was equivalent to 4% of the footprint for agricultural production.

The relatively large volume of international virtual water flows and the associated national water savings and external water dependencies strengthen the argument to consider issues of local water scarcity in a global context,” it states.

The study finds also that two factors determine the magnitude of the water footprint of national consumption - the volume and pattern of consumption, coupled with the water footprint per tonne of consumed products which, in the case of agricultural products depends on climate, irrigation, fertilisation policy and crop yield.

Some key findings:

  • The global water footprint in the period 1996-2005 was 9,087 Gm3/yr (74% green; 11% blue; 15% grey)
  • Agricultural production contributes 92% to this total footprint
  • About one fifth of the global water footprint relates to production for export
  • Mexico and Spain are the two countries with the largest national blue water savings as a result of trade
  • International trade in industrial products can be associated with an increased global water footprint equivalent to 4% of the global water footprint related to industrial production
  • The water footprint of the global average consumer in the period was 1,385 m3/yr
  • About 92% of the  water  footprint  relates to  the consumption  of  agricultural  products;  5% to  the consumption  of industrial goods, and 4% to domestic water use
  • The average US consumer has a water footprint of 2,842 m3/yr while the average citizens in China and India have water footprints of 1,071m3/yr and 1,089 m3/yr respectively
  • Consumption of cereal products gives the largest contribution to the water footprint of the average consumer of 27% followed by meat (22%) and milk products (7%) 



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