Groundwater: Depleting reserves must be protected around the world

Groundwater: depleting reserves must be protected around the world
A well brings groundwater to the surface at an oasis in Egypt. Credit: Water Alternatives Photos, CC BY-SA

Though water is central to our everyday lives and indeed life itself, we often mark World Water Day on March 22 not by reminding ourselves of all that water brings, but of the consequences of its absence or contamination.

As the American polymath Benjamin Franklin noted, "when the well runs dry, we (shall) know the worth of water." This direct reference to , the water flowing through the pores and cracks in rocks beneath our feet, is fitting as the theme of this year's water day is Groundwater: Making the Invisible, Visible.

Groundwater is our planet's invaluable natural store of freshwater but it is woefully neglected. It differs from the water running off into rivers, lakes and wetlands as this underground flow derives from precipitation that occurred years, decades or even millennia ago. Much of the estimated 23  million km³ of groundwater in the upper 2 km of the Earth's crust is ancient. Yet even the shallower and more easily accessible water, part which has been replenished by rain over the past half century, still greatly exceeds all other unfrozen water on Earth.

Found throughout landscapes on all continents, groundwater plays a vital role in not only sustaining water-dependent ecosystems during period of low or absent rainfall, but also providing people with access to , especially off-grid communities. In drylands that stretch across around 40% of the world, groundwater is often the only perennial source of freshwater. It is estimated that half of the world's drinking water and a quarter of all the water used in irrigation are currently sourced by groundwater drawn from wells and springs.

Groundwater: depleting reserves must be protected around the world
"Water, water every where nor any drop to drink"—a woman pumps fresh deep groundwater in coastal Bangladesh while surrounded by brackish surface water. Credit: Richard Taylor, Author provided

Groundwater flowing within rocks underground known as aquifers is generally more resilient to climate variability and change than surface waters. Therefore droughts—whose frequency and severity are amplified by global warming—often increase dependence upon groundwater. This was recently witnessed in Cape Town in South Africa, which narrowly avoided "day zero" when the municipal water supply would be turned off. It has even been argued that human evolution itself relied on continuous spring discharges during periods of extreme drought.

The world is expected to become more dependent upon fresh water stored as groundwater as societies adapt to a world in which rain falls less frequently but in heavier bursts brought about by climate change. Recent evidence suggests such changes in rainfall may favor groundwater replenishment in the tropics to cope with drier periods, and that irrigation with groundwater could address threats to rain-fed agriculture.

Exploited and contaminated

Despite groundwater's invaluable attributes, it is not immune to overexploitation or contamination. For instance, continued groundwater pumping in some of the world's most productive food-growing regions—California's Central Valley, the North China Plain, northwest India, the High Plains of the U.S.—is rapidly depleting reserves.

Groundwater: depleting reserves must be protected around the world
Onion crops irrigated by groundwater in southeastern Niger. Credit: Boukari Issoufou, Author provided

Similarly, some of the world's fastest growing cities such as Dhaka (Bangladesh) and Nairobi (Kenya) are struggling to reliably provide safe water as the groundwater below is running out. Groundwater depletion in both contexts disproportionately affects and farmers who are typically less able to engage in a "race to the bottom" and drill deeper wells.

Groundwater in is also becoming more salty, thanks to intensive pumping and rising sea levels, which both serve to drive sea water into underground aquifers. This salinization especially affects groundwater in low-lying nations across the world and has the potential to force millions of people to leave their homes.

Use of groundwater is also impaired by the natural leaching of pollutants such as fluoride and arsenic from their host rocks—arsenic leaking into wells in Bangladesh has been described as the largest mass poisoning in history. Human activity, be it indiscriminate use of pesticides and fertilizers in agriculture, inadequate sanitation infrastructure, or ineffective regulation of industrial practices, also threatens the sustainability of groundwater use.

Groundwater: depleting reserves must be protected around the world
Groundwater is running low in some of the world’s main agricultural areas. Credit: UNESCO, CC BY-SA

A common resource

As groundwater is out of sight, it has long been out of mind. Many countries struggle to monitor and evaluate their supplies, and only invest a tiny fraction of the resources they allocate to tracking surface water. There has also been a lack of investment in training and education in groundwater science, known as hydrogeology.

Like fisheries, groundwater is a commons, which is constantly threatened by The Tragedy of the Commons—a situation where individual users act in their own self-interest to deplete or degrade a resource, contrary to the collective good. The Nobel-Prize winning economist Elinor Ostrom showed that cooperation is possible, however. She identified a set of conditions from that included shared use of groundwater in which a community of users regulates individual access to develop common-pool resources prudently and sustainably. If we are to make groundwater visible, and ensure it provides equitable and climate-resilient access to throughout the world, then such cooperative approaches are urgently required.


Explore further

Why groundwater is one of our most precious resources

Provided by The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.The Conversation

Citation: Groundwater: Depleting reserves must be protected around the world (2022, March 22) retrieved 25 June 2022 from https://phys.org/news/2022-03-groundwater-depleting-reserves-world.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
5 shares

Feedback to editors