A map of subterranean groundwater aquifers in the world. Source: National Geographic/University of California, Irvine
When one thinks of water, one would likely not think of “infinite” – not when knowledge that water is a very much a finite resource is so commonplace. But one may think that it is renewable, that no matter how much we use and waste, the rain will fall once again, and the reservoirs and water banks will replenish themselves.
And that is true for surface water, save during times of drought – but not so much the water from the underground aquifers.
In China, an international research study led by research scientists based in Beijing have found that the capital city is sinking, the ground lowering at a rate of up to four inches (10 centimetres) a year at the rate the giant water aquifer below – the North China Plain aquifer – is aggressively pumped.
Now, the groundwater is so exhausted that Beijing, home to over 20 million residents, could be faced with such severe disruptions, its very infrastructure in building foundations, roadways, and railways could be threatened.
Already, the metropolis is one of the world’s most water-stressed cities, and its water issues are likely to get worse, not better.
But Beijing is not the only populated area experiencing this sinking, or subsidence, the effect of soil collapsing into space created as groundwater is gradually depleted – other places include Mexico City, Shanghai, and California’s Central Valley.
Around an estimated 30 per cent of the freshwater in the world is contained in the subterranean aquifers that can be found under every continent. And all over the world, alarm bells are ringing, with water experts and professionals cautioning over and over again that the underground water supply is being unsustainably depleted due to a combination of factors including drought, leaky pipes in water networks, aging wet infrastructure, population growth, inadequate technology, and higher food demand, among others.
These giant natural underground reservoirs are drying up at speeds outpacing the rate of replenishment in the form of rain. Water levels are decreasing, and the wells now have to be dug deeper, and the pumps bigger and more powerful. More devastatingly, the water being drawn is the water that should belong to those of the future generations.
According to the United Nations, there will be water scarcity on a global scale by 2030.
Around an estimated 30 per cent of the freshwater in the world is contained in the subterranean aquifers that can be found under every continent. According to National Geographic, subterranean aquifers are like “sponge-like gravel and sand-filled underground reservoirs,” and the groundwater that comes from them is only seen when it reaches the surface through wells and springs.
And for a long time, these underground aquifers, with their hidden, non-renewable groundwater, have been a backup source of water, used to help entire regions and countries weather droughts, as well as warm winters, and dry springs where there is not enough snowmelt and rainfall to replenish streams and rivers. But now, the largest subterranean aquifers are stressed, pumped at a rate that is unsustainable.
Some of the shallower aquifers can restore their water sources through surface water, but aquifers located deeper contain water that is nothing short of ancient, having been trapped there by geological changes thousands, or even millions, of years ago. These deeper aquifers cannot be replenished, and once the water is drawn, it is gone, with far-reaching implications.
But depending on groundwater to make up for depleting water supplies on the surface comes at a price. Without sufficient water, lead economist at the World Bank, Richard Damania, has forecasted that economic growth in the most water-stressed parts of the world could be stunted by up to six per cent of gross domestic product (GDP). And his study has found that climate change’s most severe impacts will further deplete precious water supplies.
“If you are in a dry area, you are going to get a lot less rainfall. Run-off is declining,” Damania told National Geographic. “People are turning to groundwater in a very, very big way.”
But Damania also conceded that controlling groundwater pumping is a tough challenge. For instance, in the United States (U.S.), farmers, though cognisant of the threat for about sixty years, have continued to draw water at an unsustainable rate from the Ogallala Aquifer.
And according to National Geographic, agriculture is the leading use of water in the globe, where irrigated farming around the world utilises more than 60 per cent of freshwater available.
“What you have in developing countries is a large number of small farmers pumping. Given that these guys are earning so little, there is very little you can do to control it,” Damania explained. “And you are, literally, in a race to the bottom.”
As nations and regions begin to experience water shortfalls, Damania continued, economic growth will fall and the prices of food will increase sharply, raising the risk of conflict and, according to the Asian Development Bank, mass migrations of a billion by 2100.
Already, Yemen is experiencing civil unrest, with the water riots in 2009 rooted in the crisis brought on by aggressively pumping groundwater. According to the Centre for Climate and Security (CCS), water scarcity was one of the driving factors behind Syria’s destabilisation and resulting civil war. Consequently, Jordan, which is heavily dependent of aquifers as a water source, is now even more water-stressed with the arrival of over 500,000 refugees from Syria.
India is drilling and drawing underground water, using it to fuel their current agricultural revolution. Unfortunately, the water will not last much longer; research scientists have estimated that as much as 25 per cent of India’s agriculture is irrigated with underground water that is not being replenished by nature. And with the revolution presently living on borrowed water and thus borrowed time, what will happen when the water runs out and the fields can no longer be irrigated?
Lead scientist of a 2015 research study led by the University of California, Irvine, that used National Aeronautics and Space Administration’s (NASA) Gravity Recovery and Climate Experiment (GRACE) satellites to examine the changes in the 37 largest groundwater aquifers in the world, Jay Famiglietti, told National Geographic that the aquifers under the gravest threat are those located at densely populated areas.
“Without sustainable groundwater reserves, global security is at a far greater risk,” Famiglietti said. “As the dry parts are getting drier, we will rely on groundwater even more heavily. The implications are just staggering and really need to be discussed at the international level.”
Additionally, the study revealed that the water supplies in regions prone to drought, including the Middle East, the North China Plain, and northern India, were diminishing.
Saudi Arabia pumped precious groundwater for agriculture at an unsustainable rate. The satellite image shows the green crops against the dry land, shown in yellow and pink. Image credit: NASA
Saudi Arabia had begun to draw water from deep subterranean aquifers in order to grow their own wheat in the arid environment about five decades ago, though they later abandoned the plan to conserve the remaining groundwater and turned to imported wheat instead.
Unfortunately, calculating the amount of remaining water in subterranean aquifers is immensely difficult. Though research scientists at the University of Victoria in British Columbia, Canada, found that less than six per cent of groundwater above two kilometres in the planet’s landmass can be renewed within the average lifespan of a human in a study published in Nature Geoscience in 2015, hydrologists have also warned that these measurements can be misleading.
But how the water is distributed in the aquifer is more important – when the water in the aquifer has fallen below 15 metres, much of it is either brackish or contaminated with so many minerals, it is simply unusable.
Moreover, while it is fairly easier to react or prepare when an obstacle or threat can be seen ahead, it is a far more difficult matter when the threat – or in this case, threatened resources – are invisible and hidden.
Granted, it can be hard to comprehend why invisible and unseen carbon emissions are changing the planet’s very atmosphere, warming the planet, and driving climate change.
For example, because all that is seen is the impenetrable surface of the ocean. It is tough to comprehend that most of the large fish from the ocean are gone, victims of overfishing, disrupting the ocean’s ecosystems and leaving a major source of food diminished.
The crisis is not visible – it is largely much like the anecdote “out of sight, out of mind.” And dwindling groundwater is one such crisis.
No one knows exactly how much water is residing under the earth’s surface, but the knowledge that the reserves are slowly emptying is prevalent. Although this most devastating crisis transcends borders and continues to grow, it is largely ignored. For what is out of sight is generally out of mind.
But fortunately, the depletion of groundwater aquifers is what scientists call a “slow-speed crisis,” according to National Geographic, so there is time to develop new technologies to counter the water shortfall and ensure water is used more efficiently. For example, Perth, Western Australia, also Australia’s driest city, replenishes their aquifer with desalinated water.
Managing and conserving the remaining groundwater, though, is an urgent challenge, as repeated droughts scorch the Earth’s surface and takes surface water supplies. But because groundwater is not an exclusive resource, but a common one available to all, cooperating and collaboration is critical as this shrinking precious resource is a line of defence against water scarcity in the future.
Sources: National Geographic, Asian Development Bank, United Nations, Nature Geoscience, the National Aeronautics and Space Administration, California Institute of Technology, the Centre for Climate and Security