Tag Archives: aquifer

Iran’s groundwater resources are rapidly depleting, and everyone should pay attention

People have been relying on groundwater resources for all their drinking and washing needs since time immemorial. But some seem to be depleting fast when faced with today’s levels of demand, a new paper reports, explaining more than three-quarters of Iran’s groundwater resources are being overexploited.

Image credits Igor Schubin.

Over 75% of Iran’s land is faced with “extreme groundwater overdraft”, the paper reports. This describes the state where the natural refill rate of an area’s groundwater deposits is lower than the rate people are emptying them at. The paper was published by an international team of researchers led by members from the Concordia University, Canada.

Drying out

“The continuation of unsustainable groundwater management in Iran can lead to potentially irreversible impacts on land and the environment, threatening the country’s water, food, and socioeconomic security,” says Samaneh Ashraf, a former Horizon postdoctoral researcher now at the Université de Montréal, and co-author of the paper.

Mismanagement of these resources seems to be the biggest issue at play, the team explains. This exacerbates the obvious difficulties that a semi-arid country would have in securing water resources. Aquifers are further hampered by inefficient agricultural practices, which further drain them needlessly.

Without urgent action, the team notes, multiple, nationwide crises can arise when groundwater levels drop too low.

Iran has around 500 groundwater basins and sub-basins, and between 2002 and 2015, an estimated total of 74 km3 of water (73 billion liters) has been drained from them. This helped increase overall soil salinity across Iran and promotes land sinking (land subsidence). The Salt Lake Basin, where the country’s capital of Tehran is located is one of the most at-risk regions for land sinking.

This is quite worrying as the region, home to 15 million people, is already quite seismically active, and at risk of being hit by earthquakes.

Public data from the Iranian Ministry of Energy was used for the study.

“We wanted to quantify how much of Iran’s groundwater was depleted,” explains co-author Ali Nazemi, an assistant professor in the Department of Building, Civil, and Environmental Engineering at Concordia University. “Then we diagnosed why it was depleted. Was it driven by climate forces, by a lack of natural recharge, or because of unsustainable withdrawal?”

Agricultural use of water was the leading cause of aquifer depletion, they explain, with Iran’s west, southwest, and northeast regions being the most affected. These are agricultural areas where strategic crops like wheat and barley are grown. Consequentially, groundwater resources are most heavily depleted in these areas.

The number of registered wells for agricultural use has doubled in the last 15 years, they explain — from roughly 460,000 in 2002 to roughly 794,000 in 2015. Overall anthropogenic withdrawals of groundwater decreased in 25 of the country’s 30 basins over the same period, which suggests consumption is being concentrated in a few, overexploited aquifers.

Ground salinity levels are also rising across the country, too, as evidenced by soil electrical conductivity readings.

The national and local governments are not able to deal with this growing issue for a variety of reasons — including international sanctions, local corruption, and low trust among the population. However, the authors explain that both short- and long-term solutions are dearly needed in order to avoid these issues ballooning into huge crises.

“In the short term, the unregistered wells need to be shut down,” Nazemi says. “But longer term, Iran clearly needs an agricultural revolution. This requires a number of elements, including improving irrigation practices and adopting crop patterns that fit the country’s environment.”

Other countries would be wise to pay attention to what’s currently happening in Iran, Nazemi adds, and learn from their mistakes.

“Iran’s example clearly shows that we need to be careful how we manage our water because one bad decision can have a huge domino effect. And if the problem is ignored, it will easily get out of control,” he says. “It also illustrates the importance of environmental justice and stewardship. These are even more important when addressing the problem of climate change.”

The paper “Samaneh Ashraf et al, Anthropogenic drought dominates groundwater depletion in Iran” has been published in the journal Scientific Reports.

Groundwater in the US is overused — and deeper wells isn’t a solution

Current water usage trends in the US are unsustainable, a new analysis suggests, and digging deeper wells isn’t going to solve the problem.

Groundwater wells across the United States. Each point on the map represents the recorded location of a well. The colors represent the purpose of the well: blue for wells constructed for domestic or municipal supply, green dots for agriculture and red dots for industry. Image credits: Perrone and Jasechko / Nature.

Ensuring water access for the planet’s inhabitants is one of the key challenges of this century, and it’s one which we’re not dealing with very well. Currently, 844 million people on the planet (around 1 in 9 globally) lack access to clean, affordable water.

It’s not just remote or underdeveloped areas (Brazil’s Sao Paulo is nearly running out of water and California’s water resources are also drying up) and it’s not just the water that we drink or wash with —  every product we use contains some “embedded water”. For instance, it takes around 20,000 pounds of water to produce one pound of beef and around 6,000 pounds to produce a t-shirt. We’re using an immense amount of water, treating it as an infinite resource — when that’s really not the case. While technically renewable, there is a finite amount of drinkable water on Earth, and more importantly, only some of that is practically accessible.

Groundwater plays a crucial role in water availability. The water stored in the ground can be compared to money kept in a bank account. If you withdraw more than you produce, you’ll end up with shortages, and this is exactly what’s going on now in many parts of the world — including the US.

“Groundwater pumped from wells in the United States provides drinking water to about 120 million Americans, supplies nearly half of all irrigation by volume, and supports industrial activities,” researchers write in a new study.

“Although groundwater is critical to domestic, agricultural and industrial activities, current withdrawals from some aquifers are unsustainable.”

A map from a separate, USGS study highlighting groundwater depletion areas.

Groundwater wells tap into aquifers all across the US. They vary greatly in size and capacity. Debra Perrone and Scott Jasechko compiled the first national database of groundwater wells, pulling together state-level data on nearly 12 million wells across the US. Their findings are concerning.

For instance, they found that as much as 89% of drilling sites in California’s Central Valley aquifer system and 73% in the Mississippi embayment aquifer system show signs of declining groundwater levels. They specifically looked at how deep water wells are being built compared to the past, the reasoning being that when groundwater levels are declining, people would dig deeper wells.

“We show that typical wells are being constructed deeper 1.4 to 9.2 times more often than they are being constructed shallower,” the researchers write. “Well deepening is not ubiquitous in all areas where groundwater levels are declining, implying that shallow wells are vulnerable to running dry should groundwater depletion continue.”

Many parts of the US are no strangers to water shortages. This issue can be bypassed temporarily by drilling deeper wells. However, drilling deeper groundwater wells is an unsustainable stopgap measure and only delays the problem without solving it, researchers find.

Areas with deeper wells are largely correlated with groundwater depletion. Image credits: Perrone and Jasechko / Nature.

This depletion of groundwater can produce a cascade of negative effects, ranging from drying of wells and reduction of water in streams and lakes to land subsidence and an overall decrease of the water quality within the aquifer. This study aims to serve as a tool for a sustainable policy to guide and protect groundwater usage.

There is a limitation to this study, particularly when it comes to the groundwater use uncertainty. Nationwide, water-use estimates are produced every 5 years. This analysis used data available at the county level, which varies spatially and seasonally. Thus, data may be of higher quality in some parts and of lower quality in other parts. Even so, this is one of the most detailed studies of its kind and paints a more detailed picture than ever before.

The study was published in Nature Sustainability.

Aquifer.

Largest freshwater aquifer of its kind found off the U.S. Northeast coast

A gigantic, relatively-fresh-water aquifer has been discovered just off the U.S. Northeast coast.

Aquifer.

Yellow crosses and the yellow dashed line show the inferred spatial extent of the low-salinity aquifer system.
Image credits Chloe Gustafson, Kerry Key, Rob L. Evans, (2019), Nature.

The aquifer is contained by the sediments of the seafloor and seems to be the largest of its kind (freshwater aquifer underneath a body of saltwater) that we’ve found so far. The aquifer stretches at least from the shore of Massachusetts to New Jersey, extending more or less continuously out about 50 miles to the edge of the continental shelf, a new study reports.

Thirsty?

“We knew there was fresh water down there in isolated places, but we did not know the extent or geometry,” said lead author Chloe Gustafson, a PhD candidate at Columbia University’s Lamont-Doherty Earth Observatory. “It could turn out to be an important resource in other parts of the world.”

The first clues that an aquifer rests in this area came in the 1970s when wells drilled off the coastline in search of oil sometimes hit fresh water. At the time, it was debated whether these were isolated pockets of water or a larger continuous body. About 20 years ago, study coauthor Kerry Key, now a Lamont-Doherty geophysicist, helped fossil fuel companies develop techniques to use electromagnetic imaging of the sub-seafloor to look for oil in this area. More recently, he decided to see if the same approach can be turned to spotting freshwater deposits in the area.

In 2015, he spent 10 days on the research vessel with Marcus G. Langseth and Rob L. Evans of Woods Hole Oceanographic Institution, taking measurements off the coast of southern New Jersey and the Massachusetts island of Martha’s Vineyard, where scattered drill holes had hit fresh-water-rich sediments. Their data indicated that these were not scattered pockets of water, but a more or less continuous structure extending from the shoreline far out through the continental shelf — in some areas as far as 75 miles. For the most part, the aquifer horizon spans from between 600 feet below the ocean floor to about 1,200 feet.

Based on the readings, the team is confident that the aquifer spans not just New Jersey and much of Massachusetts, but also the coasts of Rhode Island, Connecticut, and New York. All in all, they report, the aquifer holds an estimated 670 cubic miles of fresh water. So how did all this fresh water get there? The team was two hypotheses.

Aquifer section.

Conceptual model of offshore groundwater. Arrows denote groundwater flow paths.
Image credits Chloe Gustafson, Kerry Key, Rob L. Evans, (2019), Nature.

Some 15,000 to 20,000 years ago, toward the end of the last glacial age, most of the Earth’s fresh water was locked up as ice. In North America, these ice sheets extended through northern New Jersey, Long Island, and the New England coast. Since all of that water was solid ice, sea levels were much lower, exposing large surfaces of the continental shelf that today are submerged. As the climate warmed and the ice started melting, outflowing water formed huge river deltas on top of the shelf, and fresh water got trapped there in small pockets, eventually becoming submerged under the sea bed. This is the more traditional hypothesis as to how freshwater bodies can form beneath the ocean.

However, the team has reason to believe that the aquifer is still being fed by modern runoff from dry land. Rainfall and water infiltrating from other sources percolate through onshore sediment, Key explains, and is likely pumped towards the aquifer by the cyclical motions of the tide. This hypothesis is supported by the fact that the aquifer is generally freshest near the shore and saltier the further out you go — suggesting its water gradually mixes with that from the ocean.

This water is still less salty than ocean water. Fresh water usually contains less than 1 part per thousand of salt, and this is about the value found undersea near land; on the aquifer’s outer edges, it rises to 15 parts per thousand. Typical seawater is around 35 parts per thousand salt. As such, if water from the outer edge of the aquifer would be pumped out, it would need to be desalinated — but this would still be cheaper than processing seawater, according to Key.

“We probably don’t need to do that in this region, but if we can show there are large aquifers in other regions, that might potentially represent a resource,” he explains.

Key cites southern California, Australia, the Mideast, or Saharan Africa, as some of these regions, adding that the group hopes to expand its surveys there.

The paper “Aquifer systems extending far offshore on the U.S. Atlantic margin” has been published in the journal Scientific Reports.

Water fountain.

Groundwater pumping is bleeding the US’s rivers dry

In certain cases, rivers have lost as much as 50% of their flow.

Water fountain.

Image via Pixabay.

New research led by a hydrologist at the University of Arizona warns that massive groundwater pumping since the 1950s is bleeding rivers dry. The findings can help shape policy for the proper management of U.S. water resources, the authors say, and should be of interest especially for states such as Arizona that manage groundwater and surface water separately.

Running low

“We’re trying to figure out how that groundwater depletion has actually reshaped our hydrologic landscape,” said first author Laura Condon, a University of Arizona assistant professor of hydrology and atmospheric sciences.

“What does that mean for us, and what are the lasting impacts?”

According to Condon, this is the first study to look at the impact of past groundwater pumping across the entire U.S. Other research has dealt with this issue, but only on smaller scales.

The team started by using computer models to see what the state of U.S. surface waters would have been today in the absence of human consumption. They then compared that with surface water changes recorded since large-scale groundwater pumping first began in the 1950s.

The model maps ground and surface waters onto a grid of squares (0.6 miles per side) that covers most of the U.S., excluding coastal regions. It included all the groundwater down to 328 feet (100 meters) below the land surface. The analysis focused primarily on the Colorado and Mississippi River basins and looked exclusively at the effects of past groundwater pumping because those losses have already occurred.

Estimates from the U.S. Geological Survey (USGS) place the loss of groundwater volume between 1900 and 2008 at 1,000 cubic kilometers. “The rate of groundwater depletion has increased markedly since about 1950,” it adds, peaking between 2000 and 2008 “when the depletion rate averaged almost 25 km3 per year (compared to 9.2 km3 per year averaged over the 1900–2008 timeframe).” One thousand cubic kilometers of water corresponds to one billion liters or 264.170.000 gallons.

“We showed that because we’ve taken all of this water out of the subsurface, that has had really big impacts on how our land surface hydrology behaves,” she said. “We can show in our simulation that by taking out this groundwater, we have dried up lots of small streams across the U.S. because those streams would have been fed by groundwater discharge.”

Too much of a good thing

Groundwater is a very valuable resource across the world. When surface water sources are scarce, absent, or overtaxed, groundwater is pumped to supply our domestic and economic needs. When misused, it can lead to enormous crises, like the one facing India today.

Among other things, it is also used for agriculture and provides hydration for wild vegetation. Some native vegetation like cottonwood trees will eventually die if the water table drops below their roots. In the United States, it is the source of drinking water for about half the total population and nearly all of the rural population, and it provides over 50 billion gallons per day for agricultural needs, according to the same article from USGS.

The team found that streams, lakes, and rivers in western Nebraska, western Kansas, eastern Colorado and other parts of the High Plains have been particularly hard hit by groundwater pumping. Those findings agree with other smaller-scale studies in the region.

“With this study, we not only have been able to reconstruct the impact of historical pumping on stream depletion, but we can also use it in a predictive sense, to help sustainably manage groundwater pumping moving forward,” says Reed Maxwell, the paper’s co-author.

“We can do things with these model simulations that we can’t do in real life. We can ask, ‘What if we never pumped at all? What’s the difference?'”

The regions that were most sensitive to a lowering water table are east of the Rocky Mountains, where the water table was initially shallow (at the depth of 6-33 feet or 2-10 meters). Ground and surface waters are more closely linked in these areas, so depleting the groundwater is more disruptive for streams, rivers, and by extension, vegetation. The western U.S. has deeper groundwater, so reducing their volume didn’t have as powerful an effect on surface waters.

Condon says that other research has shown that the areas of the Midwest where precipitation used to equal evaporative demand — i.e. where irrigation wasn’t required for crops — are becoming more arid. Those are some of the regions where groundwater pumping has reduced surface waters.

“In the West, we worry about water availability a lot and have many systems in place for handling and managing water shortage,” Condon said. “As you move to the East, where things are more humid, we don’t have as many systems in place.”

The paper “Simulating the sensitivity of evapotranspiration and streamflow to large-scale groundwater depletion” has been published in the journal Science Advances.

Modhere Sacred Well.

India’s aquifers show “widespread” uranium contamination

When in India, you might want to be careful where you drink water — a new study found widespread uranium contamination in aquifer-drawn groundwater in 16 Indian states. The researchers point to over-drainage of these water-bearing bodies as a probable cause.

Modhere Sacred Well.

Modhere Sacred Well, Shenzhen, China.
Image credits Bernard Spragg / Flickr.

A new study led by researchers from Duke University reports that aquifer groundwater in India shows high levels of uranium contamination. The main source, they believe, is the chemical make-up of the rock layers which hold the water. Human activity such as pollution and over-drainage may be exacerbating the problem, however.

Dangerously uranic

“Nearly a third of all water wells we tested in one state, Rajasthan, contained uranium levels that exceed the World Health Organization and U.S. Environmental Protection Agency’s safe drinking water standards,” said Avner Vengosh, a professor of geochemistry and water quality at Duke’s Nicholas School of the Environment and paper co-author.

Data recorded during previous water quality studies revealed aquifers with similarly-high levels of uranium in 26 districts in northwestern India and in 9 districts in southern and southwestern India, the paper adds. The study is the first to highlight a widespread presence of uranium in India’s groundwater. Uranium exposure has previously been linked to health complications such as kidney disease.

Based on the findings, the team believes there is a “need to revise current water-quality monitoring programs in India” and to face the potential public health risks in areas with high levels of uranium contamination.

“Developing effective remediation technologies and preventive management practices should also be a priority,” Vengosh adds.

According to provisional safety standards set by the World Health Organization (WHO), which are consistent with standards set by the U.S. Environmental Protection Agency (EPA), around 30 micrograms of uranium per liter of water should cause no adverse effects for humans. However, uranium isn’t currently on India’s water quality watchlist, the Bureau of Indian Standards’ Drinking Water Specifications.

For the study, the team sampled and analyzed the chemistry of 324 wells in the states of Rajasthan and Gujarat. In one subset of samples, they measured the ratios of uranium isotopes. The dataset was fleshed-out with measurements from 68 previous groundwater chemistry studies performed in Rajasthan, Gujarat and 14 other Indian states.

The results suggest that there are several factors contributing to this contamination. The source is natural, the team writes — uranium contained in the aquifer’s rocks leaching out into the water. The quantity of uranium contained in the rocks of each is the first factor. The others include water-rock interactions, oxidation conditions that enhance uranium’s solubility in water, as well as the presence of chemicals in the groundwater that can interact with this extracted uranium (such as bicarbonate) which further enhances the metal’s solubility. These last three factors are specific to each water-bearing body — but, in many areas of India, they compound and lead to high concentrations of uranium in the water.

Human activity also plays a central part, the team notes. The most important culprit is over-exploitation of aquifer water for crop irrigation.

Most Indian aquifers are composed of clay, silt, and gravel resulted from the weathering of rocks in the Himalayas, or from uranium-rich granites eroded by streams. If these aquifers get drained faster than they can replenish (so water levels decline), it creates an environment ripe for oxidation — in turn, this makes what groundwater is still in the aquifer leach uranium much faster.

“One of the takeaways of this study is that human activities can make a bad situation worse, but we could also make it better,” Vengosh said.

“Including a uranium standard in the Bureau of Indian Standards’ Drinking Water Specification based on uranium’s kidney-harming effects, establishing monitoring systems to identify at-risk areas, and exploring new ways to prevent or treat uranium contamination will help ensure access to safe drinking water for tens of millions in India.”

This contamination is just the latest in a long string of problems India is having with its groundwater supply lately. Over-consumption is quickly drying its aquifers, threatening to leave its population wanting for water. But these findings show that the country’s immense drain on underground water resources is already starting to have adverse effects.

Furthermore, India’s groundwater “also suffers from multiple water quality issues such as arsenic and fluoride contamination that pose human health risks,” according to the paper.

The paper “Large-Scale Uranium Contamination of Groundwater Resources in India” has been published in the journal Environmental Science & Technology.

Drought and low aquifer levels made the Guadalupe river vanish

Vidal Mendoza, a U.S. Geological Survey hydrologic technician, has been spending his past Tuesday scanning the upper Guadalupe River, looking for the right spot to measure the flow of the water.

Perhaps more accurately, Mendoza has been spending his past Tuesday on a hot, mostly dry riverbed searching where the river should have been.

The Guadalupe watercourse.
Image via wikipedia

The Guadalupe river has been steadily going dry the last few years, this being the third time in the last five years that stretches of the river above Canyon Lake have turned to a series of shallow, standing pools, conditions not seen in the area for five decades now.

“This is what you call dry,” said Mendoza, who has worked for the USGS for 25 years. “I don’t think I’ve ever seen it like this.”

Trudging along on the dry riverbed, looking for a trickle of running water so he could perform his measurements, the pools barely came up to the calves of his thigh-high waders. But the only movement that could be discerned along the surface were the zumm and zamm of bugs and a light breeze that sent ripples along the puddles.

Finally sighting a timid trickle of water, Mendoza placed his Flow Tracker into the water to pick up a reading, but the flow was so weak the device failed to pick up a measurement. Mendoza was left estimating how little water was passing by.

The historical median flow of the Guadalupe River at Spring Branch has a value of 78 cubic feet per second for August 13, but now that value was a flat zero. The water was stagnant and filthy, with a film glistening on top in the sun and plenty of muck clouding the few inches of water.

Nearby at Comfort, where the median flow for Aug. 13 is 58 cubic feet per second, there also was no flow. Some of the water heads underground, but very little is making it to Canyon Lake.

“For all intents and purposes, the river’s dry,” said Bill West, general manager of the Guadalupe-Blanco River Authority.

The local wildlife is taking the drought pretty harshly, and many animals have started relocating for a clean drink.

“I’m heartbroken,” said Leslee Hamilton, executive director of the Guadalupe River Park Conservancy, a nonprofit that runs educational and community programs along the bank of the river. “We’ve been seeing a great increase in the number of birds and wildlife in the area… The timing of this is just devastating.”

“Every stream is slowly going dry. But it’s tough to give names and numbers,” said Gordon Becker, a fisheries scientist with the Center for Ecosystem Management and Restoration. “The system is hopelessly inadequate.”

There are efforts being taken to ease the strain on the water supply. Besides limiting lawn watering to once weekly with a hand-held hose, the measures aimed at reducing groundwater consumption by 30 percent also prohibit its use to fill swimming pools or ponds. And restrictions are bound to get even harsher.

“The deeper you get into the drought, the worse it gets,” Matt Clifford, an attorney with Trout Unlimited, said recently. “It’s grim.”

Lowest aquifer levels since 2011

Monitoring wells used by Cow Creek show the Trinity Aquifer level is at its lowest point in a decade, said Micah Voulgaris, district general manager.

“It’s 2 feet lower than it was in 2011 and 30 feet lower than in 2007,” he said, citing the average elevation of 1172.9 feet above sea level of the 14 wells by which he has tracked the aquifer level since 2003.

Not surprisingly, the drop in the aquifer directly correlates to the absence of rainfall, said Voulgaris, noting only 16 inches of precipitation has been recorded in Kendall County this year.

The lack of rain, the falling water table and cessation of flow in the Guadalupe River factored into the decision Monday to enact Stage 3 restrictions, he said, one step shy of declaring a “drought emergency,” under which all watering of lawns is banned.

In some places, the Guadalupe is dry as a stone.
Image via mysanantonio

The aquifer level’s drop has left many well pumps in the area dry, forcing homeowners to hire someone to lower pumps. When pumps are lowered as far as they can, drillers are called to dig wells deeper.

“We’re very busy with ‘no water’ calls,” said Mel Vogt, secretary at H.W. Schwope and Sons Water Well Drilling in Boerne. “A lot of it is because people just won’t stop watering” their grass, she said.

Violators of the Cow Creek drought restrictions face a fine of up to $500 if they don’t heed the first warning, said Voulgaris, who prefers not to perform the duties of water cop.

The Tarim basin

Massive aquifers beneath the world’s deserts might store more carbon than all living plants

Chinese researchers sampled water from an underground aquifer in the Tarim Basin and found these store vast quantities of carbon dioxide as a result of human activities. If the same holds true for all the desert aquifers around the world, the trapped carbon would amount to about a quarter more than the amount stored in living plants on land. Previously, the carbon trapped in aquifers was thought to be negligible. Clearly, this isn’t the case and these should not be disturbed so that the carbon doesn’t wash up into the atmosphere.

The Tarim basin

The Tarim basin. Image: geo.uu.nl

When fossil fuels are burned, 30% of the CO2 is trapped in the atmosphere where it heats it, 40% ends up in the oceans while the rest winds up elsewhere, mostly in plants which absorb it through photosynthesis. Not all CO2 taken up by plants is used and converted into sugars and oxygen. For a while, scientists have been trying to figure out where all the “leftover carbon” ends up in the planet’s system. One of these many places might be beneath the world’s deserts, according to  Yan Li of the Chinese Academy of Sciences in Urumqi, China.

Li and colleagues sampled water from the Tarim Basin, a salty aquifer under a desert in north-west China, measured the carbon content and dated it. They then compared the readings with those of water that flows into the Tarim Basin from glaciers, and with water that is used to irrigate local farms, which comes from a nearby river. This helped to draw a timeline which tells us how much carbon got into the basin and when.

Chinese researchers analyzed the stored carbon in water running in underground aquifers beneath the Tarim Basin. The amount of carbon carried by this underground flow increased quickly when the Silk Road, which opened the region to farming, began 2,000 years ago. Credit: Yan Li

Chinese researchers analyzed the stored carbon in water running in underground aquifers beneath the Tarim Basin. The amount of carbon carried by this underground flow increased quickly when the Silk Road, which opened the region to farming, began 2,000 years ago. Credit: Yan Li

Over the past 8,000 years, the amount of carbon sunk into the aquifer has risen 12 times. This is intrinsically linked to human activities, particularly farming. In sandy soil, when plants soak up CO2, some of its leaches into the ground. Microbes that breakup plant nutrients also contribute. Because conditions are arid, desert farmers have to irrigate more, but the extra water dissolves the CO2 and deposits it in the aquifer below.

“The carbon is stored in these geological structures covered by thick layers of sand, and it may never return to the atmosphere,” said Yan Li, a desert biogeochemist with the Chinese Academy of Sciences in Urumqi, Xinjiang, and lead author of the study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union. “It is basically a one-way trip.”

Collectively, the world’s underground desert aquifiers cover an area the size of North America and may account for at least a portion of the “missing carbon sink”. Knowing the precise location of these underground carbon sinks will thus prove extremely important to improve climate models. If the extent of the carbon trapping is really this large, then farmers could work together with authorities to manage the carbon that goes underground. For instance, the sinks could be exploited. The government could help farmers with subsidies so more land near deserts are farmed and more carbon is sequestrated to curve global warming.

Earth’s water basins disappearing at alarming rate, study finds

We tend to think of the Earth’s water as an inexhaustible resource; after all, you learn the basic water cycle in first grade – water moves from the rivers to the oceans and then evaporates into the atmosphere and then it comes back as rain – so how could it be disappearing? Well, the reality is much more complex than that, and as two different studies showed, we may actually be heading towards a major water crisis.

Aquifer illustration. Image via Wikipedia.

An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well. Basically, you can imagine that an aquifer is an immense underground water basin – and we get most of our drinking water from aquifers, so they have an immense importance for our society. The good news is that most land areas on Earth have some form of aquifer underlying them , but the bad news is that in some cases, these aquifers are being rapidly depleted by the human population through overconsumption.

“We’re kidding ourselves that it’s great and everything is fine,” according to Famiglietti, who is also the senior water scientist at NASA’s Jet Propulsion Laboratory. “Our groundwater supply is at risk because we’re not managing it properly, and we’re acting like we have unlimited water out there, and, of course, that’s not true.”

Now, NASA researchers have used data from satellites to analyze the 37 largest aquifers in the world.  They found that eight were being depleted with almost no natural replenishment. Five others were “extremely stressed”. The biggest problems were in Saudi Arabia, India, Pakistan and northern Africa.

The study highlights that the way we are using our water is unsustainable – and sooner or later, we will run out of water, with no solution in sight. These studies also show that existing groundwater resources are probably much smaller than previously estimated.

Image via Washington Post.

“We know we’re taking more than we’re putting back in — how long do we have before we can’t do that anymore?” said Alexandra Richey, who conducted the studies as a graduate student at UC Irvine. “We don’t know, but we keep pumping. Which to me is terrifying.”

Estimating the extent of an aquifer is no easy feat; there is no direct way to do it, and satellite data is just a start. The twin satellites — known as Gravity Recover and Climate Experiment, or GRACE, satellites — orbit the Earth and measure the gravitational pull of water over time (the water has a different gravitational pull than the surrounding ground, and these fine differences can be detected. However, there is always a certain ambiguity when working with data like this. Jay Famiglietti, senior water scientist at NASA’s Jet Propulsion Laboratory and a UC Irvine professor, said that aquifers should be studied and valued the same way as precious oil reserves – in the future, they may very well become so.

“We need to drill for water the same way that we drill for other resources,” said Famiglietti, who worked on both of the studies.

But doing this isn’t easy – in order for an aquifer to exist, it has to be capped by a layer of thick, hard bedrock. Drilling through it is not easy, and estimating the extent of the aquifer is no easy feat, but it’s certainly doable.

“We continue to pump in regions like the Central Valley without knowing how much water is in storage,” Richey said. “We need more study. We need better management.”

Huge freshwater reserves found beneath oceans

Scientists have found huge reserves of freshwater in a totally unexpected area: several kilometers offshore, beneath the oceans. This new discovery has the potential to avert or at least minimize the effects of the almost certain water crisis some areas of the world will be facing in future years.

New research suggests that half a million cubic kilometers of low-salinity water are buried beneath the seabed on continental shelves around the world. (Credit: © DJ / Fotolia)

A new study published in Nature reveals that an estimated half a million cubic kilometers of low-salinity water are buried beneath the seabed on continental shelves all around the world. The water has been located off Australia, China, North America and South Africa, but it’s very likely that the same can be found in many more areas throughout the world.

“The volume of this water resource is a hundred times greater than the amount we’ve extracted from the Earth’s sub-surface in the past century since 1900,” says lead author Dr Vincent Post (pictured) of the National Centre for Groundwater Research and Training (NCGRT) and the School of the Environment at Flinders University.
“Knowing about these reserves is great news because this volume of water could sustain some regions for decades.”

Geologists have known for some time that freshwater can be found under the seafloor, but they thought that it only occurred under rare and special conditions.

“Our research shows that fresh and brackish aquifers below the seabed are actually quite a common phenomenon,” he says.

These reserves were formed several thousands of years ago (or perhaps even more), when the sea levels were much lower than today and the coastline was further out. Dr. Post explains:

“So when it rained, the water would infiltrate into the ground and fill up the water table in areas that are nowadays under the sea. “It happened all around the world, and when the sea level rose when ice caps started melting some 20,000 years ago, these areas were covered by the ocean. “Many aquifers were — and are still — protected from seawater by layers of clay and sediment that sit on top of them.”

An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well. Basically, underground aquifers contain water and are isolated from what’s surrounding them by impermeable layers – usually clay.

While offshore drilling can be very costly, many areas of the world are overconsuming water, and, inevitably, the water reserves will start running low. As the resource is becoming scarcer and scarcer, at one point, it may likely become feasible to extract this type of water.

“Freshwater on our planet is increasingly under stress and strain so the discovery of significant new stores off the coast is very exciting. It means that more options can be considered to help reduce the impact of droughts and continental water shortages.

Journal Reference:

  1. Vincent E.A. Post, Jacobus Groen, Henk Kooi, Mark Person, Shemin Ge, W. Mike Edmunds. Offshore fresh groundwater reserves as a global phenomenonNature, 2013; 504 (7478): 71 DOI: 10.1038/nature12858

145 million year old body of seawater found under Chesapeake Bay

  • Chesapeake Bay is one of the few oceanic impact craters on Earth
  • When the huge impact took place ~35 million years ago, it sealed the ancient oceanic water
  • The water has remained virtually unchanged since then

 

A new study published in Nature provides chemical, isotopic and physical evidence that groundwater found at about 1.5 km deep under the Chesapeake Bay is actually a 145 million year old remnant of the Cretaceous North Atlantic Sea.

Image credit: Sanford WE et al.

Image credit: Sanford WE et al.

Metaphorically speaking, the aquifer described is just like a very ancient fly trapped in amber – preserving the exact conditions of the time it was sealed; the water is two times more salty than modern saltwater, providing valuable information about Cretaceous salinity. The entire setting was created with the “help” of a massive comet or meteorite that struck the area, its impact basically creating Chesapeake Bay.

“Previous evidence for temperature and salinity levels of geologic-era oceans around the globe has been estimated indirectly from various types of evidence in deep sediment cores. In contrast, our study identifies ancient seawater that remains in place in its geologic setting, enabling us to provide a direct estimate of its age and salinity,” said lead author Dr Ward Sanford of U.S. Geological Survey.

Chesapeake Bay is one of only a few impact craters that have been identified and described in oceanic waters. It’s estimated that the impact took place some 35 million years ago, ejecting enormous quantities of debris and creating humongous tsunamis that probably reached as far as the Blue Ridge Mountains, over 150 km away. This study not only highlights an underground structure that can provide valuable information about the marine environment from the Cretaceous, but it also helped geologists better understand the Chesapeake Bay itself.

“This study gives us confidence that we are working directly with seawater that dates far back in Earth’s history,” said Jerad Bales, acting U.S. Geological Survey’s Associate Director for Water. “The study also has heightened our understanding of the geologic context of the Chesapeake Bay region as it relates to improving our understanding of hydrology in the region.”

So how exactly was the aquifer preserved? Well generally speaking, an aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, or silt), trapped between impermeable rocks. You can think of is basically as a wet sponge in a horizontal bottle – the sponge is the permeable rocks holding water, the bottle is the layers of impermeable rock. When the big impact took place, it created such an impermeable layer, trapping the ancient water beneath it.

Researchers had a hunch that they might find something interesting there by drilling boreholes, but they had no idea just how interesting things would get.

Scientific Reference: Evidence for high salinity of Early Cretaceous sea water from the Chesapeake Bay crater. Ward E. Sanford, Michael W. Doughten, Tyler B. Coplen, Andrew G. Hunt & Thomas D. Bullen. Nature 503, 252–256  doi:10.1038/nature12714

Water demand for energy to double by 2035

energy

Water and energy are two of the things we pretty much take for granted – but we shouldn’t. Water is not infinite, and if you consume it at a high enough rate, it will run out; meanwhile, there’s a tight connection between living standard and energy consumption – and as the population continues to increase and raise its living standards, the energy demand increases as well.

Water and energy

jaenschwalde

The amount of fresh water consumed for world energy production is on track to double within the next 25 years, the International Energy Agency (IEA) explains. The main culprits for this are probably  not the suspects you’d expect though: coal and biofuels. The lesser discussed but profoundly significant energy sources are expected to dramatically gain more land.

Today, the world needs about 66 billion cubic meters (bcm) of water for energy production; if today’s policies remain in place, then you can expect the number growing to 135 bcm by 2035 – just over 20 years from now. Just so you can get an idea, that’s about four times the volume of the largest U.S. reservoir, Hoover Dam’s Lake Mead. While, of course, people working in the biofuel and coal industry claim these numbers are exaggerated, data compiled by governmental and international agencies seem to support the IEA results – some paint even a darker picture.

“Energy and water are tightly entwined,” says Sandra Postel, director of the Global Water Policy Project, and National Geographic’s Freshwater Fellow. “It takes a great deal of energy to supply water, and a great deal of water to supply energy. With water stress spreading and intensifying around the globe, it’s critical that policymakers not promote water-intensive energy options.”

Coal and biofuel

coal

China’s industrialization and economic growth is powered with coal – literally; and it’s not only them that are paying the price [China smog intensifies] – the effects are felt on an international level. China’s coal consumption on it’s own is comparable to the rest of the world combined. The thing is, even though it greatly relies on coal, the US coal consumption hasn’t grown in the last years – which is something you can only say for a few more European countries. Other than that, the entire world seems to have rediscovered the magic of coal. The thing is, coal plants are among the worst you can get; they pollute like… well, like a coal plant, while also requiring massive quantities of water. If today’s trends continue in the next 20 years, then water consumption for coal electricity alone will rise with about 84 percent, from 38 to 70 billion cubic meters annually. Coal plants could be less water-extensive, the IEA explains, but the process would be more expensive and not as efficient.

After coal, the much-hailed biofuel comes next. For some reason, people seem adamant to ignore the fact that at the moment, biofuel does much more harm than good. The agency anticipates a 242 percent increase in water consumption for biofuel production by 2035, from 12 billion cubic meters to 41 bcm annually – but here’s the kicker! The amount of energy biofuels will deliver will continue to be modest!

Just so you can get an idea on how water extensive this energy source is, biofuels like ethanol and biodiesel now account for more than half the water consumed in “primary energy production” (production of fuels, rather than production of electricity), while providing less than 3 percent of the energy that fuels cars, trucks, ships, and aircraft. They are also nowhere near as efficient as traditional hydrocarbon sources.

Hunger games

biofuel

Experts worry that this impending shortage of water will occur at the same period when a shortage of food and water are expected. What, didn’t you know that if we continue to grow our population at this rate, we will soon run out of food and water? After all, there’s only so many people we can feed, and the projections for 2035 show a popullation of 9 billion.

Biofuels, in particular, will siphon water away from food production,” says Postel. “How will we then feed 9 billion people?”

Hydraulic fracking will not have a global impact as big as biofuels and coal, but the regional impact will definitely be significant. An average of 15 million liters of water (~4 million gallons) are required for the fracking process, for each well ! A good oil site has at least 50-100 wells – and this can add a lot of stress to the local water supply. So what’s the sollution?

If this trend continues, things will become pretty dire. What can we do? We can try to harness the untapped potential that our planet has, in a win-win situation; renewable energy sources are only starting to make an impact, and hopefully, that impact will increase as years go by.

“There is still enormous untapped potential to improve energy efficiency, which would reduce water stress and climate disruption at the same time,” she says. “The win-win of the water-energy nexus is that saving energy saves water.”

Via National Geographic

Demand for water bigger than supply

Groundwater use is unsustainable in many of the world’s major agricultural zones; as a matter of fact, about a quarter of the world’s population lives in regions where groundwater is being used up faster than it can be replenished, concluded researchers.

The planet thirsts

Picture from the study. Click it for full size.

Our entire civilization depends on our water supply, and aside from agriculture, pretty much all industrial processes require vast quantities of water – water that has been stored up to thousands of years in various aquifers. Aquifers are underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be extracted with wells. Some aquifers are absolutely massive, stretching across several countries and providing agricultura, industrial and drinking water for millions and millions of people. However, in most of the world’s major agricultural areas, including the Central Valley in California, the Nile delta region of Egypt, and the Upper Ganges in India and Pakistan, the demand is larger than the supply.

“This overuse can lead to decreased groundwater availability for both drinking water and growing food,” says Tom Gleeson, a hydrogeologist at McGill University in Montreal, Quebec, and lead author of the study. Eventually, he adds, it “can lead to dried up streams and ecological impacts”.

Overexploatation

It’s not that the planet doesn’t have enough water – the truth is that we’re using it recklessly. Gleeson and his colleagues combined a global hydrological model and a date set of groundwater use to estimate how much water is extracted by countries throughout the world. They also analyzed another important factor: the aquifers’ rate of recharge – the speed at which groundwater is replenished. Using this approach, they managed to calculate the groundwater ‘footprint’ for nearly 800 aquifers worldwide; and the importance of this study is huge.

“To my knowledge, this is the first water-stress index that actually accounts for preserving the health of the environment,” says Jay Famiglietti, a hydrologist at the University of California, Irvine, who was not involved in the study. “That’s a critical step.”

The authors found that some 20% of the world’s aquifers are being overexploited – some heavily so. For example, the the groundwater footprint for the Upper Ganges aquifer is more than 50 times the size of its aquifer, so the rate of extraction is highly unsustainable, Gleeson notes – a dramatic fact, considering how over 200 million rely on water from that aquifer.

The truth is dire, Gleeson estimates. He believes that a even more thorough study would find even more aquifers in dramatic, unsustainable situations. But, he also adds, there is still hope: as much as 99% of the fresh, unfrozen water on the planet is groundwater. “It’s this huge reservoir that we have the potential to manage sustainably,” he says. “If we choose to.”

Study