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Wednesday, March 22

"Where has all the water gone?" Fast-depleting aquifers in USA and elsewhere

"Another USGS study that looked at aquifer depletion levels across the U.S., including Alaska and Hawaii from 1900 to 2008, also found the process of depletion is speeding up. The water loss between 2000 and 2008 represents about 25 percent of the total loss of 1,000 cubic kilometers that has taken place in the 108-year span. The amount of water we’re talking about could fill Lake Erie twice. A lot of that water pulled from the ground eventually ends up making its way to the oceans, since more water is coming in than can go out through evaporation and other means. This raises global sea levels.

"While there are 64 aquifer systems in the country, 30 of them account for 94 percent of the total withdrawals. Dennehy says the largest amount of groundwater (56,900 million gallons per day across the U.S.) is used for irrigation, followed by the public water supply, which uses 16,000 million gallons per day. Self-supplied industrial uses come in third, with 3,570 million gallons per day."


 -- From Even Without a Drought, We’re Depleting Groundwater at an Alarming Pace; July 2015; Modern Farmer

Water supply: The emptying well
By Margaret Catley-Carlson
Nature international weekly journal of science, 542, 412–413 (23 February 2017) doi:10.1038/542412a
Published online 22 February 2017

The article is Catley-Carlson's review of High and Dry: Meeting the Challenges of the World's Growing Dependence on Groundwater by William M. Alley & Rosemarie Alley
Yale University Press: 2017


It is astonishing to many that lakes and rivers account for less than one-third of 1% of global fresh water. Some 95% of unfrozen fresh water resides unsung and underground, dimly visible at the bottom of a well or gushing from a pump. Big cities such as Buenos Aires and entire countries, including Germany, depend hugely on groundwater. About 70% of it goes into irrigation, accounting for more than half of irrigated agriculture — which in turn provides nearly half of the global food basket. In large parts of India, groundwater is egregiously overdrawn. 


And everywhere, aquifers are poorly measured and managed. As a result, no scientific consensus exists on the details of this vast and vital source of fresh water — although there is consensus on the fact that we face a worldwide problem.

In High and Dry, hydrologist William Alley and science writer Rosemary Alley encapsulate the crisis in a description of the US High Plains Aquifer, which spans eight states from South Dakota to Texas. “This virtual ocean of groundwater, which accumulated over thousands of years, is being used up in decades,” they write. 

In three ways, the book provides a deep and broad understanding of groundwater use and abuse, mostly in the United States but with some international scope.

First, it abounds in case studies, many centering on grand, polarizing projects. In the early twentieth century, engineer William Mulholland fomented water wars in California by diverting the Owens River to Los Angeles; that process has ultimately led to groundwater pumping in the Owens Valley. Today, Texas tycoon T. Boone Pickens has tried to sell water from the Ogallala Aquifer to municipalities. 

In the mid-1980s, Libyan leader Mu'ammer Gaddafi masterminded the Great Man-Made River, a piping system fed by the Nubian Sandstone Aquifer, to service the country's dry reaches. 

India, the Alleys show, swiftly progressed from famine to food exporting beginning in the 1960s. That astonishing development was driven mostly by private pumps (16 million of them as of 2010) using free electricity to pull water from an ever-lower water table.

The authors also delve into Australia's Murray–Darling basin, which has been overpumped and overused, largely because of allocations based on volumes in high-water years. And they explore how water politics in apartheid-era South Africa denied non-whites adequate water rights for rural development. These stories are crucial to global understanding of current imbroglios, and they are told with verve.

The second achievement of High and Dry is its excellent distillation of aquifer science. There are clear descriptions of how geology and geography affect the depth or movement of water, the relation of aquifers to stream flow and how these stores recharge. Pollution of aquifers by pesticides, fertilizers, pharmaceuticals and arsenic is thoroughly laid out, as is arsenic poisoning, which remains slow and expensive to treat. The Alleys show how artesian wells can push pressurized water into the atmosphere and aquifer depletion can cause subsidence of metres per decade, which plays havoc with railways and sewers.

Finally, the book unpicks the tangles that impede groundwater governance. In the United States, the “secret, occult and concealed” nature of the resource, as an 1861 court ruling had it, rendered regulation impossible. US history accordingly reveals a rich tapestry of legal suits, counter suits, interstate conflicts, water theft, treaties, compacts, agreements, accords, lobbying, bullying and temporizing. 

Yet national water governance is slowly finding ways to measure and manage water use as technology and awareness grow. In the American West there are several, sometimes competing, fundamental water laws. 

[...]

***
I have omitted several more interesting points in the review but while Catley-Carlson closes with a few criticisms of the book, including that it's 'U.S.-centric,' from all the above it's obviously worth the read for those trying to get a handle on the threat to aquifers around the world. 

See also my recent posts on polluted surface water and groundwater:

"Not a single Indian city can provide potable tap water"
India's groundwater crisis is even worse than its surface water crisis

"80 percent of India's surface water may be polluted ..."

70-90 percent of China's water table is polluted, polluting its food supply

And from National Geographic, As Groundwater Dwindles, a Global Food Shock Looms; December 22, 2016

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