Thursday, June 16, 2011

Virtual water is unable to redress usage inequalities

Nadya Anscombe in Environmental Research Web: Similar to the idea of embodied carbon, the transfer of virtual water – the amount of water it takes to produce goods or a service – has been suggested as a way of redressing inequalities in water use. But, according to research published in Environmental Research Letters (ERL), virtual-water transfers between countries are unlikely to solve this issue because a nation's freshwater usage tends to be dominated by the agricultural industry.

David Seekell and his colleagues from the University of Virgina, US, looked at United Nations data on total renewable water resources, agricultural water footprint, industrial water footprint, population, reference evapotranspiration and arable land. They looked for inequality in water usage such as over-consumption, where for example 10% of the population uses 50% of the water or under-consumption, where for example 50% of the population uses 10% of the water. They found that overall, inequality in water usage is relatively minor when compared with the natural inequality imposed by geography and climate in the distribution of total renewable freshwater resources between nations. This is because water-rich countries do not fully exploit their renewable freshwater resources.

…The team found that the inequality in total water footprint minus the virtual-water footprint gives the same amount of inequality as the total water footprint. "This shows that the direction of current virtual-water transfers is insufficient to reduce inequalities," said Seekell. "Internal agricultural production contributes 76% to the overall water-use inequality among nations. Currently, not enough virtual water is transferred to completely overcome inequalities in internal water use because the contribution from internal agriculture is so large."…

USGS image of a water pocket in the Grand Wash at Capitol Reef

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