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Farmers Deplete Fossil Water in World’s Breadbaskets

The views expressed are those of the author and are not necessarily those of Scientific American.

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Irrigation has helped farmers feed a population that has now reached 7 billion people. But in many places farmers have overused underground aquifers that have taken thousands of years to form, drawing down the fossil water much faster than it can be replaced. The Ogallala aquifer in the American high plains, along with similar aquifers in Mexico, Eastern Europe, Egypt, Arabia, Iran, India and China, represent the crisis zones for humanity’s groundwater footprint, according to a new analysis published in Nature on August 9. (Scientific American is part of Nature Publishing Group.) Here’s what the world’s groundwater footprint looks like:

View a Larger Version of the Map

As shown, the “footprint” (gray) represents how much water people are drawing from the aquifer, compared with how much the aquifer actually holds (in red, orange or yellow, depending on how bad the water imbalance is). The imbalance exists because these aquifers support agricultural zones much larger than their physical extent. These areas also happen to be some of the most vitally important agricultural regions of the world. In fact, 1.7 billion people in these regions rely on these waters directly—each and every one of them facing a looming water crisis. And in times when the rains fail—such as is occurring now throughout the Ogallala aquifer region in the U.S.—such fossil water is the only hope to keep crops from failing too.

The problem with drawing too much water from an aquifer, which has been stored in these geologic formations for thousands of years, is that it can’t easily be restored once pumped dry. That’s the crisis facing farmers who rely on the Ogallala Aquifer, which once contained enough water to cover the entire continental U.S. roughly half-a-meter deep. Once pumped dry, the Ogallala would take at least 6,000 years to refill.

Another complication of pumping too much water from an aquifer is that creeks will run dry and surface waters can literally be sucked back underneath the surface. That’s not good for wildlife. Yet the world needs more water to meet the demand of a growing population for food.

As the map shows, however, the world actually has vast reserves of fossil water in places like Siberia and throughout Africa and South America. And then there are the easily rechargeable aquifers like the Floridan Aquifer in the southeastern U.S. or the lower portion of the Ganges River in India. These aquifers can be drawn down and then recharged by a good storm or monsoon.

So the question confronting us as we struggle to adapt to this new age of man, or Anthropocene, is whether we can learn to sustainably manage these groundwater resources. Or whether we’ll pump them dry and then have to wait for the fickle rains of a changed climate to sustain us.

Image: Gleeson et al. / Nature

David Biello About the Author: David Biello is the associate editor for environment and energy at Scientific American. Follow on Twitter @dbiello.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. massymule 8:49 pm 08/9/2012

    I wondered if I’d live to see the day man’s overpopulation would directly impact his life… I estimate 3 billion too many of us…

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  2. 2. 11:08 pm 08/9/2012

    The whole system is completely messed. Governments are promoting irrigated monocrops from the food pyramids to the corn subsidies. The Ecosystem Farming Theory is the solution to our environmental crises.

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  3. 3. Rudy Haugeneder, Canada 11:34 pm 08/9/2012

    For those folks worried about drinking water supplies, let them drink wine.
    For farmers worried about water for crops, let them recycle pee and squished poop, both of which can produce abundant grape crops — and more wine, the nectar of the Gods.

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  4. 4. kienhua68 12:34 am 08/10/2012

    It’s almost funny to read how man is going to cope with
    water resources. Nature will tend to it if we don’t
    stop population growth soon.
    We have played the game of wanton resource use and are in
    the early throes of realization.
    People are actually finding out there are limits and the
    price of ignoring it.

    Link to this
  5. 5. jtdwyer 8:32 am 08/10/2012

    Nicely done article!

    The global population has nearly tripled since I was born in 1950. The population of the U.S. has more than doubled in the same period; it has quadrupled since 1900. Moreover, it was only recently that most U.S. residents live in cities rather than rural areas, so the population increase is greatest in larger cities. The effects seem to smack me in the face everywhere I go.

    The most critical issue for agricultural overuse of non-replenished water aquifers is that, even worldwide, farms are now large businesses operated for profit. What possible mechanism can cause global farm industries to moderate their depleting use of critical water resources?

    Since the global population is expected to increase from 7 billion to 9 billion by 2050 and the harvestation of nutrients from sea fishing appear to be diminishing, it seems unlikely that sufficient resources will be available to meet the expected demand.

    Only by managing demand (population) and resource usage can potentially catastrophic conflicts be avoided.

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  6. 6. Poppa beer 2:37 am 08/11/2012

    Good to look at your map ans see that our farmers here in New Zealand are NOT among the guilty…………..or have we just been ignored once again ??

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  7. 7. Patricia Berg 1:19 pm 08/11/2012

    Great map & article– thank you for clarifying this issue. I notice a color yellow on the map that does not match the graph key to water stress levels.

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  8. 8. JerryWood 10:53 pm 08/11/2012

    Future research needs to focus on measuring ice below the land mass: To measure this volume of ice and its melt rate has not been properly funded.

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  9. 9. jng1207 5:47 pm 08/12/2012

    Dear David Biello: Your data on northwestern Mexico are completely out of reality. Recently, 2011-2012, we have demostrated with 8 fully producing groundwater wells (@ 160 lps: 2,400 gpm, each one), in an area ”overexploited”, in Hermosillo City; that there is plenty of groundwater and, even more, it’s being discharged to the sea in the Golfo de California (Sea of Cortez)…If you request more field information, we’ll gladly sent it to you…All the best: Jesús Nájera-Garza, Ph.D. Hydrogeologist.

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  10. 10. HubertB 7:07 pm 08/12/2012

    In the United States, the misuse of water could possibly be reversed. No reason exists why during wet years excess water could not be used to replenish the Ogallala Aquifer rather than flush it down the river into the Gulf of Mexico. Dams and deep wells could make more sense than the present system.

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  11. 11. bucketofsquid 5:49 pm 08/13/2012

    A shortage of water will never be a major issue for any industrialized nation with a coastline. The creation of a nation wide water pipeline grid will be costly but far cheaper than an illegal war. With water desalination and purification plants we can insure the availability of water for all. By charging for water use as most cities already do we can divide the cost fairly among the end users with the biggest users paying the biggest bills.

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  12. 12. Rich102 10:32 pm 08/13/2012

    The sort of water supply system that bucketofsquid envisions would require huge amounts of energy to operate, but fortunately could probably utilize intermittent solar and wind power fairly effectively. Nuclear and geothermal would be other candidates, but fossil fuels would create more problems than they would solve in such a system.

    It would be interesting if the editors of Scientific American could find someone to write a good article on this idea.

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  13. 13. IslandGardener 5:07 am 08/14/2012

    Two books worth reading for the background on this.

    Jared Diamond, ‘Collapse: how societies choose to fail or survive’ (2005). He points out how civilisations have fallen in the past, and he puts our current problems in perspective, and reminds us that it can happen.

    Tony Allan, ‘Virtual Water: Tackling the threat to our planet’s most precious resource’ (2011). One of his essential points is that civilisations which rely on irrigation rather than rain to grow their food will fail, sooner or later.

    We need to grow food where the rain is, and we need to grow crops which can thrive in the places they’re grown with the existing rainfall.

    That includes more perennial crops, especially trees and shrubs with edible seeds, fruits and leaves. J. Russell Smith gave many examples (such as sweet chestnuts, Castanea sativa) in his classic book ‘Tree Crops: A permanent agriculture’ (1950).

    So one last book suggestion – Martin Crawford, ‘Creating a Forest Garden’ (2010).

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  14. 14. JerryWood 12:56 pm 08/15/2012

    Recharging depleted aquifers was not covered in this blog; Currently, there are programs doing so, like in the High Plains Region. This is an accepted practice worldwide. History, living in the arid climate of the middle east has taught their people to adapt by constructing artifical lens to refocus the surface water and recharge their watering holes have been noted and studied…

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  15. 15. Steve3 5:51 pm 08/16/2012

    Jesús Nájera-Garza,

    I don’t understand how pumping rates are supposed to signify that water is plentiful.You can pump until Oops! It’s suddenly all gone!

    Link to this

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