The earth is dry, and still drying. Farmers cultivate barren land, and governments panic over depleting water sources and try to water parched cities, exemplified by China’s idea of building a pipe extending more than 1,000km for its drought-stricken Northwest region. And that is only the beginning; new research shows that the subterranean aquifers – essentially the globe’s reserve water sources – are depleting.
If this problem persists, the repercussions could be calamitous, especially for Asia, rapidly urbanising and already water-stressed.
Subterranean aquifers are water deposits found deep underground, in penetrable soil, sand, and rock, holding around 100 times of the supply of water observed on the surface of the earth, whether in the wetlands, rivers, streams and lakes. In some parts of the world, they idle just a few hundred metres below the surface.
Recycled wastewater and desalinated seawater will not be able to close the widening global water gap – projected to hit 40 per cent by 2030 – between water supply and demand. And so subterranean aquifers are being mined more and more to generate power, provide the water agriculture depends on, and simply meeting the daily use in rapidly-urbanising metropolises – Asia is urbanising at an estimated rate of 120,000 people per day.
Presently, around 30 per cent of the freshwater the world uses comes from the subterranean aquifers. The University of California conducted a study over a decade between 2003 and 2013, and found that one third of the 37 largest aquifers they looked at were extremely diminished, having collected little or no provisions from rainfall. A number of the most afflicted aquifers were in the some of the driest locations in the world, including Asia.
The Asian continent is to home an estimated third of the globe’s land irrigated by groundwater, with China, India, and Pakistan consuming the most. South Asia by itself uses up half the groundwater expended around the globe. With up to 88 per cent of Asia already water-stressed, the subterranean aquifers found in Asia are no longer being routinely refilled with rainfall.
Instead, the boreholes are being dug deeper and the water tables are following suit. In the Punjab Province, located in Pakistan, water tables are being pushed down by up to half a meter per year due to over-pumping, not just threatening future water and food security, but also making crops like rice and sugarcane harder to grow.
Asia burgeoning population, which has the potential to surge by 25 per cent to hit five billion by 2050 – will burden energy, food, and water supplies even more, straining already-stressed resources to the limit. Climate change will aggravate it further.
But the issue does not end there – over-pumping of groundwater, observed in places like the Punjab Province, is currently leading to soil decline, and some Asian metropolises are beginning to show the results by sinking. Certain locales in Beijing are slowly submerging at the rate of several centimetres per year, and up to 80 per cent of North Jakarta could end up below sea level by 2030.
On top of all this, exhausted aquifers close to coastlines are exposed to contaminants found in seawater, leaving land infertile. A few aquifers have been found to be tainted with arsenic, which naturally materialises deep underground. More than half of the groundwater in the Indo-Gangetic aquifer has been estimated to contain salt or arsenic, according to a recent study by Nature Geoscience. In Bangladesh, over 40,000 deaths a year are attributed to water contaminated with arsenic.
On way to improve the current situation is to determine exactly how much groundwater is left, and how it is currently being used. The National Aeronautics and Space Administration (NASA) satellite for the Gravity Recovery and Climate Experiment passes on information on alternations in the earth’s gravity as a result of seesawing water volumes. The amount of surface water available and how much is being consumed by who can be figured out by applying remote sensing technology to river basins.
Another method is to review and upgrade groundwater pricing. It can be politically tough to implement as nations would have not only craft the policies best suited for them, but the legal infrastructure would also need to be installed and carried out. Australia, China and Mexico have tried this approach, and have witnessed varying levels of success.
But the true challenge with this method is getting rid of the subsidies provided for gas and electricity, which have the effect of encouraging farmers to pump groundwater throughout the day. If the subsidies cannot be revoked, there are other innovative alternatives. For instance, in Gujarat, India, the government offers power to the farmers for only eight hours a day. Farmers may have all the groundwater they need, as well as the power, but they cannot have it for whole days. This initiative has lowered the rate of groundwater pumping.
The restoration of subterranean aquifers can also be explored. Uttar Pradesh state in India gathers surplus floodwater in storage ponds and from there, the collected water flows into the water table.
Finally, water management on surface water can be reviewed and upgraded, and curtail any temptation to keep running to groundwater. An estimated 80 per cent of wastewater is being discharged into rivers and various other waterways, polluting them. Focusing more attention on this avenue would be simpler by far, both politically and strategically, than the other options.
Subterranean aquifers should not be at the top of the water list; instead, they should be the globe’s last resort. If they are not safeguarded and preserved, the coming generations will pay a stiff price.
Source: The Guardian