Groundwater from aquifers important factor in food security

A press release from the University of Illinois News Bureau: Thirsty cities, fields and livestock drink deeply from aquifers, natural sources of groundwater. But a study of three of the most-tapped aquifers in the United States shows that overdrawing from these resources could lead to difficult choices affecting not only domestic food security but also international markets.

University of Illinois professors of civil and environmental engineering Ximing Cai and Megan Konar, along with graduate student Landon Marston and Lehigh University professor Tara Troy, studied groundwater consumption from three main aquifer systems. Reliance on these aquifers intensified so much from 2000 to 2008 that it accounted for 93 percent of groundwater depletion in the U.S. They published their findings in the Proceedings of the National Academy of Sciences.

The U.S. Geological Survey identifies the Central Valley aquifer in California, the High Plains aquifer in the Great Plains states, and the Mississippi Embayment aquifer in the lower Midwest as being managed unsustainably, which means that water is being extracted from the aquifer faster than it is replenishing. ... The researchers tracked water consumption from the aquifers to see where the water was going, both in terms of geography and usage. For example, when water was used to irrigate a crop, the researchers tracked where those crops were shipped.

“When we think of water, we think of direct water, the water that comes out of our faucets. But we actually use a lot of embodied water in our everyday lives – the water footprint to produce a product,” Konar said. “We looked at the water implicitly being transferred between states and countries in the products.”

The researchers found that the vast majority – 91 percent – of embodied groundwater from these three aquifers stayed within the U.S. The remaining 9 percent was exported internationally. They identified the states most heavily reliant on each aquifer, and the breakdown of what was produced using water from each aquifer. For example, the largest percentage of water from the High Plains aquifer irrigated grains, while the largest contribution from the Central Valley aquifer in California went to producing meat...

A groundwater irrigation pump in the UK, shot by John Poyser, Wikimedia Commons via Geograph UK, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Greenland ice stores liquid water year-round

University of Utah News Center: Researchers at the University of Utah have discovered a new aquifer in the Greenland Ice Sheet that holds liquid water all year long in the otherwise perpetually frozen winter landscape. The aquifer is extensive, covering 27,000 square miles.

The reservoir is known as a “perennial firn aquifer” because water persists within the firn – layers of snow and ice that don’t melt for at least one season. Researchers believe it figures significantly in understanding the contribution of snowmelt and ice melt to rising sea levels. The study was published online Sunday, Dec. 22, in the journal Nature Geoscience.

“Of the current sea level rise, the Greenland Ice Sheet is the largest contributor – and it is melting at record levels,” says Rick Forster, lead author and professor of geography at the University of Utah. “So understanding the aquifer’s capacity to store water from year to year is important because it fills a major gap in the overall equation of meltwater runoff and sea levels.”

Forster’s team has been doing research in southeast Greenland since 2010 to measure snowfall accumulation and how it varies from year to year. The area they study covers 14 percent of southeast Greenland yet receives 32 percent of the entire ice sheet’s snowfall, but there has been little data gathered.

In 2010, the team drilled core samples in three locations on the ice for analysis. Team members returned in 2011 to approximately the same area, but at lower elevation. Of the four core samples taken then, two came to the surface with liquid water pouring off the drill while the air temperatures were minus 4 degrees Fahrenheit. The water was found at about 33 feet below the surface at the first hole and at 82 feet in the second hole.

“This discovery was a surprise,” Forster says. “Although water discharge from streams in winter had been previously reported, and snow temperature data implied small amounts of water, no one had yet reported observing water in the firn that had persisted through the winter.”...

Drill rig used to extract firn cores from within the Greenland firn aquifer. One of the snowmobiles used in the 300 km traverse of the ice sheet to reach the drill site. Pictured, Clément Miège (co-author and PhD student University of Utah), and Terry Gacke (Ice Drilling Design and Operations). Photo Credit: Evan Burgess

High plains aquifer is running dry for farmers

Futurity.org: Significant portions of one of the largest bodies of water in the United States are at risk of drying up if draining continues at the current rate. In the current issue of Earth’s Future, scientists are proposing alternatives that will halt and hopefully reverse the unsustainable use of water drawdown in the Ogallala Aquifer, also known as the High Plains Aquifer, which spans from Texas to South Dakota and drives much of the region’s economy.

“Already, there are regions in Texas and Kansas where farmers can’t pump enough water to meet the demands of their crops,” says Bruno Basso, an ecosystem scientist at Michigan State University. “If current withdrawal rates continue, such depletion will expand across extensive portions of the central and southern areas served by the aquifer during the next few decades.”

Despite the widespread, rapid decline of the water table, the number of irrigated acres across the region continues to increase. The situation isn’t completely dire, though, say researchers who offer policy solutions to avert some aspects of this water crisis.

Federal crop insurance could be changed to allow substantial water reductions, especially crops categorized as fully irrigated. An example of such a sustainable model was recently proposed by the governor of Kansas that could save significant amounts of water and could be adopted regionally.

Another sustainable approach would be to adopt wholesale precision agriculture strategies. These would allow farmers to identify which areas in fields need more water and fertilizer. New precision agriculture strategies combine GPS technologies with site-specific management to apply optimal amounts of water and nutrients, which will increase farmer’s profitability and reduce environmental impact....

A 2009 map of water-level changes in the High Plains/Ogallala Aquifer in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming, 1980 to 1995. Created from public domain data produced by the USGS and made available in Open-File Report 99-197[1][2]. Authors: Fischer, Brian C.; McGuire, Virginia L.

Africa faces water crisis despite discovery of huge aquifers

Space Daily via UPI: The recent discovery of two vast aquifers in northern Kenya and Namibia has given weight to scientists' claims the African continent is sitting on immense underground reservoirs of water. But the scientists also warn that Africa faces more droughts because of climate change and could have 25 percent less water by the end of the century, setting the state for possible water wars.

Egypt and Ethiopia, for instance, are facing off over the long-contested waters of the Nile River because Addis Ababa is building a giant $4.3 billion hydroelectric dam, which will cut the flow to Egypt, whose 84 million people depend on the Nile to survive.

The U.S. global security consultancy Stratfor cautioned the September discovery of the aquifers in the drought-plagued Turkana desert of northwestern Kenya near the borders with Uganda and South Sudan raises "the possibility of cross-border conflicts over water rights in the future."

The Lotikipi Basin Aquifer and the smaller Lodwar Basin Aquifer were among five aquifers located by Radar Technologies International of France, in collaboration with the Kenyan government and the United Nations with funding from Japan.

The East African aquifers were discovered using advanced satellite technology and confirmed by drilling. The size of the other three Kenyan acquifers still has to be determined by drilling. Lotikipi, roughly the size of Rhode Island, contains an estimated 7.3 trillion cubic feet of water with an annual recharge rate of 42.4 billion cubic feet through rainfall in Kenya and Uganda....

NASA image of Lake Turkana in Kenya and Ethiopia, not far from the recently discovered aquifers

Nitrogen fertilizer remains in soils and leaks towards groundwater for decades

Terra Daily via SPX: Nitrogen fertilizer applied to crops lingers in the soil and leaks out as nitrate for decades towards groundwater - "much longer than previously thought," scientists in France and at the University of Calgary say in a new study. Thirty years after synthetic nitrogen (N) fertilizer had been applied to crops in 1982, about 15 per cent of the fertilizer N still remained in soil organic matter, the scientists found.

After three decades, approximately 10 per cent of the fertilizer N had seeped through the soil towards the groundwater and will continue to leak in low amounts for at least another 50 years. The study was led by researcher Mathieu Sebilo at the Universite Pierre et Marie Currie in Paris, France, and by Bernhard Mayer in the U of C's Department of Geoscience, and included several research organizations in France.

Their paper, "Long-term fate of nitrate fertilizer in agricultural soils," was published this week in the Proceedings of the National Academy of Sciences of the United States of America. The findings show that losses of fertilizer N towards the groundwater occur at low rates but over many decades, says Mayer, U of C professor of geochemistry and head of the Applied Geochemistry Group.

That means it could take longer than previously thought to reduce nitrate contamination in groundwater, including in aquifers that supply drinking water in North America and elsewhere, he says. "There's a lot of fertilizer nitrogen that has accumulated in agricultural soils over the last few decades which will continue to leak as nitrate towards groundwater," Mayer says....

From Geoff Ruth's  High School Earth Science 1-13.pdf (page 493), Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Scientists prodded on massive Namibian aquifer

New Era (Namibia): The Minister of Agriculture, Water and Forestry, John Mutorwa has urged water scientists to move faster in making the hydrological research results into a massive underground aquifer publicly known.

He was referring to the recent newly discovered aquifer called Ohangwena II, that spans the northeastern region and, which flows under the boundary between Angola and Namibia. “Ohangwena has (underground) water. We had a meeting at State House to discuss drought. Cattle are dying. Then we asked, when are we going to utilise the water resources in Ohangwena? At one point those results must be known and be used in one way or another to solve a practical problem which is drought,” stressed Mutorwa. “If you found water, let the donkeys, cattle and farmers tell us that they drank that water.” Mutorwa who was speaking yesterday during the first two-day regional workshop on groundwater resources governance in trans-boundary aquifers, which Namibia, Botswana and South Africa share outlined the importance of water in arid Namibia. “Water is fundamental to the existence of life.”

The workshop is organised by the Ministry of Agriculture in partnership with Unesco to discuss the implementation of the regional – Groundwater Resources Governance in Trans-boundary Aquifers and the Stampriet-Kalahari/Karoo Aquifer project. The main goal of the project is to enhance cooperation on water security, reduce trans-boundary and water-use conflicts, and improve overall environmental sustainability. The project also aims to reinforce the capacity building of member states in managing groundwater resources; to strengthen cooperation among stakeholders and countries sharing aquifers, as well as to develop a long-term strategy for the monitoring and governance of trans-boundary aquifers. He urged governments involved in the project to redouble their efforts and to ensure that they support research initiatives and other activities through funding....

A red sand dune in Namibia, shot by Rui Ornelas, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Massive water discovery in Kenya's desert

Paula Kahumba in the "Africa Wild" blog at the Guardian (UK): UNESCO and the Kenya Government today announce the discovery of one of the worlds largest underground water aquifers in the desert north of Turkana, an area best known for fossils, famine and poverty. The finding by Radar Technologies International (RTI) was made using space based exploration technology called WATEX system. The largest aquifer at 250 billion cubic meters of water which is equivalent in volume to Lake Turkana one of the largest lakes in the Great Rift Valley, and 25 times greater than Loch Ness. More importantly the annual recharge rate, the amount of water that can be sustainably exploited per year, is estimated to 3.4 billion cubic meters, nearly three times the water use in the New York City.

The man behind the RTI is the energetic white haired French Alain Gachet who says the worst thing he has ever seen in his life is people dying of thirst. "This discovery will transform Turkana. In 10 years time I see no more suffering, no more dying of hunger or thirst, people will have schools, roads, farms. Life will be much better for them and famine will be a thing go the past".

For Turkana where malnutrition rates can be as high as 37%, this discovery Is better than oil. It is an opportunity for local development. Ikal Angelei is the Director of Friends of Lake Turkana, an organzation that champions the rights of the Lake's communities and ensure their involvement in decision-making on issues relating to the Lake and its environment.

"This is an extremely exciting find for my community. While we celebrate however, we must be wise. The first thing we must do is confirm the recharge rate so that we do not kill the golden goose, and we must also protect against speculators and unscrupulous people who threaten to take it away from the local communities. The Kenyan leadership must plan carefully to ensure that in developing the resource we protect and respect the rights and the needs of local communities who must benefit."...

The town of Kalokol in the Turkana Desert, shot by Mr.matija.kovac, Wikimedia Commons,  under the Creative Commons Attribution-Share Alike 3.0 Unported license

Ogallala Aquifer being drained by U.S. farmers

Seed Daily via UPI: The Ogallala Aquifer, a reservoir of groundwater underlying eight western states, is being rapidly drained, Kansas State University researchers say.

In a study released Monday, a research team led by David Steward, a professor of civil engineering, predicted the aquifer will be 69 percent depleted by 2060 at current rates of use. Replacing the water in the aquifer would take from 500 to 1,300 years, Steward said.

The aquifer, part of the High Plains Aquifer System, underlies parts of Texas, New Mexico, Oklahoma, Kansas, Colorado, Wyoming, Nebraska and South Dakota, taking its name from the town of Ogallala, Neb. More than one-quarter of the irrigated farmland in the United States gets its water from the Ogallala.

In 1960, the aquifer was only 3 percent depleted. That has increased to 30 percent. Steward predicts farmers will continue to become more efficient in their use of water, helped by crops bred or genetically designed to use less. He expects water use to peak in 2025 and crop yields to increase until about 2040. After that, he said, depletion of the aquifer will depend on what choices are made....

The Ogallala Aquifer and the location of a proposed Keystone Pipeline crossing over it. How's that for sheer stupidity? Shot by 570ajk, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

New insight on vulnerability of public-supply wells to contamination

US Geological Survey: Key factors have been identified that help determine the vulnerability of public-supply wells to contamination. A new USGS report describes these factors, providing insight into which contaminants in an aquifer might reach a well and when, how and at what concentration they might arrive. About one-third of the U.S. population gets their drinking water from public-supply wells.

"Improving the understanding of the vulnerability of public-supply wells to contamination is needed to safeguard public health and prevent future contamination," said Suzette Kimball, acting USGS Director. "By examining ten different aquifers across the nation, we have a more thorough and robust understanding of the complexities and factors affecting water quality in our public supplies."

The study explored factors affecting public-supply-well vulnerability to contamination in ten study areas across the Nation. The study areas include Modesto, Calif., Woodbury, Conn., near Tampa, Fla., York, Nebr., near Carson City and Sparks, Nev., Glassboro, N. J., Albuquerque, N. Mex., Dayton, Ohio, San Antonio, Tex., and Salt Lake City, Utah.

Measures that are crucial for understanding public-supply-well vulnerability include: 1) the sources of the water and contaminants in the water that infiltrate the ground and are drawn into a well; 2) the geochemical conditions encountered by the groundwater; and 3) the range of ages of the groundwater that enters a well.

 "Common sense might say that wells located near known contaminant sources would be the most vulnerable, but this study found that even where contaminant sources are similar, there are differences in public-supply-well vulnerability to contamination," said Sandra Eberts, the study team leader....

A water tower in Mystic, Connecticut, shot by Ad Meskens, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Parched Jordan to tap ancient aquifer

Space Daily via AFP: Jordan, one of the world's 10 driest countries, said it will start pumping water from a 300,000-year-old southern aquifer on Thursday to the capital and other cities to help them meet high demand.

"An experimental pumping of water from the wells of the Disi aquifer will start at midnight (2100 GMT) Wednesday," Water Minister Hazem Nasser told the state-run Petra news agency.

The much-awaited $990 million project seeks to extract 100 million cubic metres (3.5 billion cubic feet) of water a year from the Disi aquifer, 325 kilometres (200 miles) south of Amman.

The water ministry says Jordan, where 92 percent of the land is desert, will need 1.6 billion cubic metres of water a year to meet its requirements by 2015, while the population of 6.8 million is growing by almost 3.5 percent a year.

"The pumping will contribute to solving Amman's water problems in a week, while other cities will start witnessing improvement in water supplies within a month," Nasser said.

Officials say the project has required 250,000 tonnes of steel and the digging of 55 wells to pump water from Disi to Amman, where the per capita daily consumption of its 2.2 million population is 160 litres (42 gallons)...

A tomb near Petra, Jordan, shot by Jean Housen, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported, 2.5 Generic, 2.0 Generic and 1.0 Generic license

Sri Lankan aquifer depleting from overuse

Dilrukshi Handunnetti in SciDev.net: The single limestone aquifer, which is the main source of freshwater in Sri Lanka's northern Jaffna peninsula, is gradually depleting through overuse, researchers say.

"The area suffers from severe groundwater imbalance which might reach crisis proportions in the future," Shanti de Silva, one of two scientists who carried out the research for the agricultural department of the University of Jaffna, told SciDev.Net.

 At a presentation of the research results last month (18 April), de Silva called for a regulatory framework to optimise groundwater use in Jaffna peninsula — which was captured by the Sri Lankan army from separatist rebels in May 2009, ending decades of civil strife.

Originally published in Tropical Agricultural Research (in December 2012), the results showed that  the potential recharge of the aquifer in the dry season was approximately 14 per cent of that in the wet season — showing up a serious contrast between the two main seasons.

"Water resources of the basin remain almost constant while the demand for water continues to increase. Moreover, due to uneven distribution of rainfall, water resources lack replenishment," the report said.

...The researchers recommend extraction of 50 per cent of the annual recharge to prevent a severe imbalance developing in the aquifer, the main resource for agriculture, domestic use and water supply on the Jaffna peninsula....

Dried up in Jaffna, Sri Lanka, shot by Gerald Pereira, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Viruses from sewage contaminate deep well water

Janet Pelley in Chemical & Engineering News: Scientists once thought that pathogens could not reach drinking water wells sunk into deep, protected groundwater aquifers. Nevertheless, over the past decade, researchers have identified diarrhea-causing viruses at a handful of deep bedrock well sites in the U.S. and Europe. Now, researchers in Madison, Wis., report where these pathogenic viruses may have originated. The viruses appear to seep from sewer pipes and then swiftly penetrate drinking water wells....

The U.S. Environmental Protection Agency does not regulate the presence of viruses in drinking water, so many public water systems do not routinely test for them. In a 2007 study, a team of researchers, including Mark Borchardt, a microbiologist with the U.S. Department of Agriculture, and Kenneth Bradbury, a hydrogeologist at the University of Wisconsin-Extension, in Madison, investigated the integrity of aquifers confined beneath a thick layer of clay or ... Groundwater models predicted that surface contaminants would require tens to hundreds of years to reach wells in these aquifers, which typically sit more than 700 feet underground. Even if pathogens did find their way to the groundwater, they should be dead after that amount of time. “But we were shocked to find human-specific viruses—some of which were still infectious—in every well we sampled in Madison,” Bradbury says.

This group and others in the field suspected that leaking sewer pipes were the source, so the scientists launched a sampling program to determine how the pathogens got into the wells. Every two to four weeks, the team sampled sewage at the city’s waste treatment plant and water pumped from six wells prior to any disinfection. They identified viruses and measured their concentrations in the samples using real-time quantitative polymerase chain reaction.

Viruses appear and disappear in the human population on a monthly cycle, which allowed the researchers to track their presence in sewage and well water, Borchardt says. After the team detected viruses in the sewage, the same viruses appeared simultaneously in all six wells a few weeks later, usually after rain or snowfall melt. The scientists could correlate when the pathogens popped up in the well water with their appearance in the sewage system.

What’s more, the scientists cultured the viruses from the wells and showed that they were still infectious. Virus concentrations similar to those found in the study are sufficient to cause vomiting and diarrhea, Borchardt says. However, “because Madison chlorinates its water, no one has become sick,” Bradbury adds....

A surface aerator at a water treatment plant, shot by Trlabarge, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

In drought ravaged plains, efforts to save a vital aquifer

Jim Malewitz in Stateline: …Threatened by another summer of crop-shriveling drought, Kansans are watching a bold experiment unfold in Sheridan County, population 2,556, a sliver of the state’s northwest corner. On lands dominated by agriculture, locals have agreed to across-the-board cuts to water use.

The state of Kansas didn’t order the cuts, nor did a regional entity. Rather, at a time when states and locals are jockeying for water, stakeholders in the 100 square-mile “high priority” (meaning particularly parched) zone of Northwest Kansas Groundwater District 4 reached a consensus to reduce groundwater pumping by 20 percent over the next five years. They are gambling on short-term wants for a longer-term need — to preserve the aquifer their lives depend upon. “We’re doing it because we think it’s right,” said Wayne Bossert, the district’s manager. “We have high hopes for it.”

Sheridan’s plan is just one of many major efforts to fend off a slow-moving disaster with national implications: The High Plains Aquifer, which feeds some of the world’s most productive croplands, is running dry.

The aquifer, also called the Ogallala, is one of the world’s largest underground sources of freshwater.  It stretches 174,000 square miles through the middle of the country from South Dakota to Northwest Texas, touching parts of Kansas and five other states, watering more than one-quarter of all irrigated acreage in the U.S. and some of world’s largest grain cattle feedlots. The Ogallala also provides drinking water to four of every five people living above it.

For decades, farmers and others have been slurping up groundwater far faster than nature can recharge it. Since Americans first began to seriously irrigate the Great Plains, beginning in the 1940s, water levels across most of the Ogallala have fallen at least five feet, according to the U.S. Geological Survey. Almost one-fifth of the area has dropped at least 25 feet, while 11 percent has lost 50 feet or more. In some of the worst-off areas of Kansas and Texas, the water table has declined as much as 200 feet. The most recent drought has compounded the problem, drying up riverbeds and forcing farmers to rely even more heavily on groundwater….

US Geological Survey Map of the Ogallala Aquifer. The hotter the color, the worse the decline

Groundwater fate and climate change

Phys.org: Simon Fraser University earth scientist Diana Allen, a co-author on a new paper about climate changes' impacts on the world's ground water, says climate change may be exacerbating many countries' experience of water stress.

"Increasing food requirements to feed our current world's growing population and prolonged droughts in many regions of the world are already increasing dependence on groundwater for agriculture," says Allen. "Climate-change-related stresses on fresh surface water, such as glacier-fed rivers, will likely exacerbate that situation. "

Add to that our mismanagement and inadequate monitoring of groundwater usage and we may see significant groundwater depletion and contamination that will seriously compromise much of the world's agriculturally-grown food supply." In "Ground Water and Climate Change," Allen and several other international scientists explain how several human-driven factors, if not rectified, will combine with climate change to significantly reduce useable groundwater availability for agriculture globally.

The paper was published in late 2012 in the journal Nature Climate Change. The authors note that inadequate groundwater supply records and mathematical models for predicting climate change and associated sea-level-rise make it impossible to forecast groundwater's long-range fate globally....

Image by Hans Hillewaert, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Too soon to tap Namibia's groundwater find, experts say

Servaas van den Bosch in SciDev.net: The extraction of the much needed water from a large underground aquifer in northern Namibia may need to wait for further studies, officials have warned at a water investment conference.

The aquifer, discovered in July, may contain enough water to sustain about one million people living in the area for 400 years at the current consumption rate, as well as boost development through irrigation in this poor, heavily overgrazed area where women and children walk for hours to get fresh water from boreholes.

But officials and scientists have cautioned against too much optimism until further studies have been conducted. One reason is that  the aquifer is under a smaller, polluted water resource, so it is still unclear how it could be tapped.

"We need to determine the extent of the water reserve and its accessibility first. There is a lot of brackish [partly salty] water in the area," Abraham Nehemia, under-secretary at Namibia's agriculture, water and forestry ministry, told SciDev.Net on the sidelines of the Namibia Water Investment Conference, held this month (12–14 September) in the capital, Windhoek.

Heike Wanke, a hydrogeologist at the University of Namibia, also warned against rushing into exploitation. "The positioning near a polluted aquifer means boreholes must be drilled at appropriate places," Wanke said, adding that studies on the age of the aquifer which will also inform sustainable extraction rates have not been completed yet....

Ancient dunes from the Namib-Naukluft Park in Namibia, Africa. A great shot by Bjørn Christian Tørrissen from his book, One for the Road by B.C. Tørrissen, also available from an online gallery. Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported

The gravity of water

NASA Earth Observatory: The signature of drought was easy to read in the southern United States in the summer of 2011. It was in the brown, wilted crops and the bare fields. It was in the clouds of dust that rolled across the sky and in the shrinking reservoirs. It was in the fires that raced through crisp grasslands and forests, devouring homes and wilderness. It was in the oppressive heat that returned day after day.

Drought was harder to see as 2011 drew to a close. With the return of winter, rains began to fall and temperatures dropped. But the drought was still there, lingering beneath the surface. It was still apparent to hydrologists who test the wells that plunge deep into underground aquifers.

In Nebraska, Brian Wardlow and colleagues at the National Drought Mitigation Center watched the drought long before and after the average citizen paid heed. Wardlow develops satellite-based products that experts use—along with more traditional ground observations—to assess the severity of drought. Looking at measurements from the satellites, Wardlow could see broad-scale changes in groundwater supplies at varying depths over large swaths of the South.

Measurements of underground water storage (aquifers)—rather than surface water (lakes, rivers, etc.)—reveal the long-term effects of drought. This map shows ground water conditions in the U.S. during the week of November 28, 2011, compared to the long-term average. A time-series animation shows the evolution of ground water from 2002 to 2012. (Map by Chris Poulsen, National Drought Mitigation Center, based on data from the GRACE science team.)

After a year without much rain, it was no surprise that the drought lingered below the land’s surface. “Groundwater takes a long time to be depleted, but it takes a long time to be recharged as well,” says Wardlow, a remote sensing specialist at the University of Nebraska–Lincoln. From experience, he expected regional groundwater supplies to be diminished. But this time he could see it in greater detail than traditional well measurements had ever provided....

Measurements of underground water storage (aquifers)—rather than surface water (lakes, rivers, etc.)—reveal the long-term effects of drought. This map shows ground water conditions in the U.S. during the week of November 28, 2011, compared to the long-term average.  Map by Chris Poulsen, National Drought Mitigation Center, based on data from the GRACE science team.

Vast aquifer found in Namibia could last for centuries

Matt McGrath in BBC World Service: A newly discovered water source in Namibia could have a major impact on development in the driest country in sub-Saharan Africa. Estimates suggest the aquifer could supply the north of the country for 400 years at current rates of consumption.

Scientists say the water is up to 10,000 years old but is cleaner to drink than many modern sources. However, there are concerns that unauthorised drilling could threaten the new supply.

For the people of northern Namibia water is something that they either have too much of or too little. The 800,000 people who live in the area depend for their drinking water on a 40-year-old canal that brings the scarce resource across the border from Angola.

Over the past decade the Namibian government have been trying to tackle the lack of a sustainable supply in partnership with researchers from Germany and other EU countries. They have now identified a new aquifer called Ohangwena II, which flows under the boundary between Angola and Namibia....

The Grootberg Plateau in Damaraland, in north central Namibia, shot by markos, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Drought caused big drop in Texas portion of Ogallala Aquifer

Kate Galbraith in the Texas Tribune: The historic Texas drought caused the Ogallala Aquifer to experience its largest decline in 25 years across a large swath of the Texas Panhandle, new numbers from a water district show.

The 16-county High Plains Underground Water Conservation District reported this week that its monitoring wells showed an average decline last year of 2.56 feet — the third-largest in the district’s 61-year history, and three times the average rate over the past decade. Farmers pumped more water during the drought to compensate for the lack of rainfall, which was about two-thirds less than normal last year in Lubbock and Amarillo.

Further north in the Panhandle, along the state's border with Oklahoma, a second water district also registered large declines in the Ogallala. Steve Walthour, the general manager of the eight-county North Plains Groundwater Conservation District, calculated on Monday that the average drop in the Ogallala reached 2.9 feet last year.

"We’ve seen some pretty heavy declines," Walthour said, noting that the west side of his district got hit especially hard Given the catastrophic nature of the drought, which was the most intense in recorded state history, some farmers said things could have been worse.

“You never want to pull that much down, but under the circumstances I think we’re probably coming out pretty well,” said Tommy Fondren, who rents out his land in Crosby County for cotton farming....

A saturated thickness map of the Ogallala Aquifer, with the proposed Keystone Pipeline highlighted in red. Map by 570ajk, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Groundwater depletion in semiarid regions of Texas and California threatens U.S. food security

Newswise: The nation's food supply may be vulnerable to rapid groundwater depletion from irrigated agriculture, according to a new study by researchers at The University of Texas at Austin and elsewhere The study, which appears in the journal Proceedings of the National Academy of Sciences, paints the highest resolution picture yet of how groundwater depletion varies across space and time in California's Central Valley and the High Plains of the central U.S. Researchers hope this information will enable more sustainable use of water in these areas, although they think irrigated agriculture may be unsustainable in some parts.

"We're already seeing changes in both areas," said Bridget Scanlon, senior research scientist at The University of Texas at Austin's Bureau of Economic Geology and lead author of the study. "We're seeing decreases in rural populations in the High Plains. Increasing urbanization is replacing farms in the Central Valley. And during droughts some farmers are forced to fallow their land. These trends will only accelerate as water scarcity issues become more severe."

Three results of the new study are particularly striking: First, during the most recent drought in California's Central Valley, from 2006 to 2009, farmers in the south depleted enough groundwater to fill the nation's largest man-made reservoir, Lake Mead near Las Vegas—a level of groundwater depletion that is unsustainable at current recharge rates.

Second, a third of the groundwater depletion in the High Plains occurs in just 4% of the land area. And third, the researchers project that if current trends continue some parts of the southern High Plains that currently support irrigated agriculture, mostly in the Texas Panhandle and western Kansas, will be unable to do so within a few decades.

California's Central Valley is sometimes called the nation's "fruit and vegetable basket." The High Plains, which run from northwest Texas to southern Wyoming and South Dakota, are sometimes called the country's "grain basket." Combined, these two regions produced agricultural products worth $56 billion in 2007, accounting for much of the nation's food production. They also account for half of all groundwater depletion in the U.S., mainly as a result of irrigating crops....

Groundwater depletion has been most severe in the purple areas indicated on these maps of (A) the High Plains and (B) California's Central Valley. These heavily affected areas are concentrated in parts of the Texas Panhandle, western Kansas, and the Tulare Basin in California's Central Valley. Changes in groundwater levels in (A) are adapted from a 2009 report by the U.S. Geological Survey and in (B) from a 1989 report by the USGS.

Groundater pumping is causing seas to rise

LiveScience: People around the world are pumping so much water out of the ground, and releasing it back into the environment, that it's causing oceans to rise, a new study reveals. The effect is bigger than you might expect. The research estimates that by 2050, seas will rise about one-third of an inch (0.8 mm) per year due to groundwater pumping, and it may rival melting glaciers as a primary cause for rising seas.

Groundwater pumped for irrigation, drinking water and industrial uses does not typically end up back underground. Instead, it flows into streams or rivers or evaporates into the atmosphere, eventually finding its way to the ocean.

Other studies have shown that many aquifers — natural underground lakes that have built up water over millions of years — are being pumped dry. The ground tends to compact when the water is extracted, and once pumped dry, often an aquifer can never store as much water as it once did — sort of like a sponge that’s lost its sponginess.

“Other than ice on land, the excessive groundwater extractions are fast becoming the most important terrestrial water contribution to sea level rise,” said Yoshihide Wada, with Utrecht University in the Netherlands and lead author of the study, detailed in Geophysical Research Letters, a journal of the American Geophysical Union.

...In the coming decades, Wada said groundwater contributions to sea level rise are expected to become as significant as those of melting glaciers and ice caps outside of Greenland and the Antarctic. Already rising seas are causing some islands to disappear. In March, a study found that 4 million Americans are threatened by rising seas....

Image from the US Geological Survey