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Recent studies have found that humans are using up water at a faster rate than it is being replenished. Judy Woodruff talks to James S. Famiglietti, a professor of Earth system science and civil and environmental engineering at the University of California, Irvine, about what this dwindling supply of freshwater means, and whether we should be concerned about it.
Hundreds of millions of people around the world depend on the use of underground rock formations known as aquifers to get the clean water they need. But a pair of new studies show many of the largest aquifers are being depleted at alarming rates.
As seen on this map, of the 37 largest ones in the world, 21 are losing more water than is being replaced, with those areas in orange and red showing much more serious problems with depletion. These are located in countries like China, Russia and Australia, as well as India, where water resources are already a major problem.
The reports also identify declining levels for California's Central Valley Aquifer.
Jay Famiglietti is a lead author on one of the reports from NASA's Jet Propulsion Laboratory. And he joins me now.
Welcome, Mr. Famiglietti.
Remind us, what is an aquifer, and how does it produce the clean water?
JAY FAMIGLIETTI, NASA Jet Propulsion Laboratory:
An aquifer is an underground soil or rock unit that contains — contains water in its pore spaces, and the way we get at that water is by drilling wells and pumping it up from the subsurface.
So, what did these two studies find?
We found that in the 37 world's largest aquifers that we looked at, that over 21 of them are past sustainability tipping points, meaning that the rate of withdrawal exceeds the rate of replenishment. And of those, we found that 13 are in a pretty bad way and threatened to exceed a point at which they may not come back.
And why is this happening?
Well, we rely heavily on groundwater. But yet we don't manage it very well.
Around the world, we use about — about two billion people rely on groundwater as the primary water source. And it provides about half of the water that we need to irrigate agriculture. So we rely on it heavily. But we don't manage it very well. And that's true in the United States as well as around the world.
So, is this depletion happening at a faster rate than it did historically?
In some places, yes.
It's taken awhile for population in a particular region to develop, or it's taken awhile for the infrastructure to come into place. For example, in Northwestern India, the green revolution is something that didn't start until the 1960s and the 1970s. Prior to that, there wasn't much groundwater depletion.
Let's talk for a minute about where this is happening. We mentioned on several continents. Where is the problem the worst?
Probably the worst in the Middle East, the Arabian Peninsula, and even the region above the Arabian Peninsula. Turkey, Syria, Iraq, and Iran are regions that we have studied before.
Northwestern India, really across Northern India, into Bangladesh is in pretty rough shape. The North China Plain, the big aquifer system around Beijing — it is true it's on every continent. The Pilbara mining region, which is the Canning Basin in Northwestern Australia. Several of the aquifers in Africa are in rough shape because there's very little rainfall there in the Sahara Desert, so not very much replenishment.
And in Argentina, the Guarani aquifer, and then, of course, the aquifers of the United States, big ones being the Central Valley, and the High Plains, or the Ogallala Aquifer.
And what about the one in California's Central Valley? What shape is that in?
Well, that's in pretty rough shape.
This study and other studies that we have done on the aquifer show that we have been losing about 5.5. trillion gallons of groundwater per year for the last four years during this drought. And that's because in California right now, there's no snow in the mountains, there's no rainfall happening, there is very little water in our reservoirs. So, we have to rely on this groundwater, and it's disappearing pretty rapidly.
Is there a way of knowing when this water is going — how much more water there is, when it's going to run out? And is there anything that can be done about this?
So, that's an excellent question. That was really the topic of the second paper.
And so we tried to expose the fact that we really don't know how much water we have in the world's major aquifers. Again, it's true in the United States and it's true around the world. We know that we're passed the sustainability tipping points and all kinds of ecological damage is occurring.
And we know that the water tables are falling and wells are running dry. So I think it's very important that we think very carefully about exploring the world's major aquifers to understand how much water is actually there.
Well, it's a grim, grim set of findings that I know a lot of people are going to be paying close attention to.
Jay Famiglietti, we thank you for being with us.
Thank you very much.
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