A 2010 study of the world’s vast reserves of underground water – called groundwater – has found that we’re draining it twice as fast today as in 1960. Marc Bierkens, a research hydrologist with Utrecht University in the Netherlands, led the groundwater study. He said we’re taking water out faster than it’s being replenished. He told EarthSky:
There’s quite a large amount of groundwater that is extracted in excess to what is naturally recharging to the groundwater, to the aquifers, which means that there’s quite a lot of groundwater depletion going on.
Most of the groundwater we use is used for growing food. The fastest groundwater losses, said Bierkens, are in some of the world’s leading agricultural centers – India, Pakistan, China, and the central valley of California in the U.S. And, Bierkens said, there’s a connection between what we eat in one part of the world and groundwater depletion in other parts of the world. He said:
For instance, if I go to the supermarket, and I buy melons, these melons are grown in the southeast of Spain. They’re grown with irrigated water, obtained from groundwater depletion.
Dr. Bierkens and colleagues estimated the loss of groundwater across the entire world. The used a global computer model to come up with how much rain and snow seeps through soil and recharges underground aquifers. They combined it with a database of country-by-country groundwater use in order to map global groundwater net losses and gains. One thing that scientists don’t yet know about groundwater is just how much total there is in the world, or exactly when a given area’s groundwater will hit empty. More studies and better computer models, said Bierkens, might give people better advance warning of groundwater shortages.
This cannot be deduced from our study, when this will happen. That it will happen is for certain if we don’t see any change in the system, in behavior, when it will happen requires additional study.
Bierkens said the extracting more groundwater than is recharged is not sustainable.
In a couple of decades or so you will run into the limits of that system and run into food shortages. That will be, in the long run, a problem for more of the developing countries with exploding population numbers. For more of the developed countries in the U.S., a lot of the cash crops are exported, for instance to Europe. So what you see is that an important part of the economy thrives on irrigated crops. An important part of that irrigation water comes from groundwater, and you’re depleting it, you will see that there will be economic problems in that region, eventually.
He spoke about a sustainable use of groundwater.
When you look at sustainable use of groundwater, and you look at the developing countries with increasing population numbers, the only serious way of counteracting this problem is.seeing that population growth decreases. That’s basically the most effective way of getting it done. Of course there are some other more technical solutions that can be done. For instance, the Chinese are thinking about diverting part of the Brahmaputra River up north to the drier areas up north for use in irrigation. Of course this will affect the people of Bangladesh, as nothing comes for free when it comes to that.