New measure developed for sustainability of global
groundwater water supply points to overuse of water in Asia and
North America
Farmers are unsustainably exploiting groundwater in a number of
important agricultural regions, according to a team of researchers
led by Prof. Tom Gleeson of McGill’s Department of Civil
Engineering, in collaboration with researchers from Utrecht
University in the Netherlands. Indeed, widespread groundwater
depletion has recently been reported in aquifers (the underground
sand, gravel or rock formations that hold groundwater) around the
world. In a recent article published in Nature, the
researchers estimate that approximately 1.7 billion people, most of
whom reside in Asia, live in areas where groundwater resources
and/or groundwater-dependent ecosystems are under threat.
By combining data of groundwater usage gathered from each
nation, with global hydrology models, the researchers have
developed a new way of measuring water use relative to supply in
aquifers around the world. They call it the groundwater footprint.
And like the ecological footprint, which has become the common
measure for calculating human demands on the biosphere relative to
its ability to regenerate, the groundwater footprint is designed as
a location-based measure of the sustainability, or lack thereof, of
human groundwater use around the planet.
A single example is telling. It takes about 140 litres of water
to grow the coffee beans that go into your morning cup of coffee,
whether the beans are grown on an arid plateau in Ethiopia or in a
Columbian rain forest. But the effect of this water use on the
supply of available water will be very different. Until now, there
has been no way of quantifying the impact of such agricultural
groundwater use in any consistent, global way.
By using aquifers as the scale for analyzing water budgets – the
inputs and outputs of water from regions – the researchers have
created a map of the globe, showing regional differences in the
groundwater footprints. They suggest that the groundwater footprint
will offer water scientists, managers and policy makers an
intuitive tool to better visualize groundwater depletion, suggest
where groundwater could be used sustainably to increase
agricultural yields and better manage groundwater sustainably
within countries.
The research was funded by the Natural Sciences and
Engineering Research Council of Canada and the Canadian Institute for Advanced
Research.
To view the paper: http://www.nature.com/nature/journal/v488/n7410/full/nature11295.html
