The artesian springs and oases of the world’s drylands are remarkable lifelines, with critical ecological and cultural significance. These natural discharge points of aquifers create biodiversity hotspots in otherwise inhospitable terrain, serving as critical refuges for unique flora and fauna found nowhere else on Earth. Yet these precious ecosystems rank amongst the most threatened on the planet, facing pressures from aquifer drawdown, spring extinctions, invasive species, and direct human modification. In a companion story to our recent webinar, ‘Lifelines in the Desert: the critical role of oases in biodiversity and heritage’, we explore these remarkable aquifer systems, their role in biodiversity and human culture, and the importance of their conservation.
Precious groundwater
Nearly one-third of the world’s freshwater exists as groundwater, which is found in underground aquifers. These ancient geological formations are largely made of porous rock that collect millennia and sometimes millions of years’ worth of rainfall.
Rainfall enters an aquifer at elevated ‘recharge’ areas, usually hills or mountains at the edge of an aquifer. As this water seeps through caverns, fractures and pores it creates what geologists call a ‘ saturated layer’. In a confined aquifer, the saturated layer is bounded above and below by ‘aquitards’ — geological layers with low permeability such as dense clay, shale or solid rock. Many aquifers, particularly large ones, have multiple saturated layers and aquitards.
The movement of water within the saturated layer is influenced by pressure, as well as gravity, which provides a hydraulic gradient as the water moves downward. Australia’s Great Artesian Basin (GAB) provides a perfect example of these phenomena.
Top: extent of the Great Artesian Basin (light blue) (image source: Wikimedia Commons)
Bottom: cross-section diagram of the GAB, showing the directional flow of groundwater beneath the surface, and indicating the natural discharge points at the surface (image source: Qld Gov Wetland Info, Creative Commons)
The GAB covers 1.7 million square kilometres across most of the eastern third of the continent. It is the largest aquifer in the world. Most of its recharge areas are found along the forested Great Dividing Range in NSW and Queensland, where rainfall enters exposed sandstone.
The entire GAB is under enormous pressure from the landmass that sits on top of the aquifer, says Professor Rod Fensham, an internationally recognised expert on spring ecosystems from the University of Queensland
“You can think of it like a pressurised balloon full of water being squashed by a blanket,” he says.
Water ultimately discharges at much lower elevations via several thousand natural springs in the desert lowlands along the fringes of the Basin. It’s not unusual for the water to travel great distances between recharge and discharge points, providing a unique connection between dissimilar climate zones.
Springs tend to emerge when geological features such as fault lines or a rise in bedrock beneath the aquifer brings the groundwater close to the surface. Sometimes it’s the other way around and depressions in the land bring the surface closer to the groundwater. At any of these points, pressurised water percolates to the surface, forming a spring. As moisture from the spring creates conditions capable of sustaining plant and animal life, a spring can give rise to an oasis.
Top left: aerial view of Dalhousie springs in South Australia. Top right: Dalhousie springs close up. Bottom image: Springs water flowing on The Peake Station in South Australia. (credit all 3 images: Kirrily Blaylock)
Stunning Biodiversity
Dryland Springs, and the oases that form around them, are like ‘inverse islands’ says Dr Renee Rossini ecologist at the University of Queensland’s School for the Environment. They’re glimpses of moisture surrounded by an expanse of dry land. Much like islands in the ocean, springs and oases are hotspots of biodiversity and high levels of endemism. There are two key reasons for this:
- Artesian springs can persist for extraordinarily long periods of time, ranging from many millennia to millions of years; and
- The surrounding drylands were not always so dry
Australia’s vast dry interior was once covered in lush, river-strewn ecosystems, including rainforests, wetlands and riparian vegetation. But over millions of years the global climate cooled and became drier. Aridification on the Australian continent was especially intense. Wet inland ecosystems contracted, giving way to shrublands, grasslands and desert. Many plant and animal species went extinct as their habitats vanished, but some survived. Permanent artesian springs continued to flow even as the surrounding landscape became inhospitable. As such, they became evolutionary refugia for water-loving species that had nowhere else to go.
A spring is not necessarily a very stable place to live,” says Renee, explaining that conditions in springs can be precarious and prone to extremes, especially at the edges. Temperatures can spike or plummet in the desert, and the volume of water in a spring changes across seasons. Meanwhile, nutrients and minerals accumulate, altering the local chemistry. The size, shape, and varying depths of a spring also create different microclimates and microhabitats.
““[In a spring] you’ve got these nice deep, permanent places that stay pretty much stable all the time and these shallow impermanent places on the edges,” says Renee, explaining that an animal living in the shallows at the spring’s edge might be exposed to water that’s saltier than the sea, acidity as high as pH 10 and water temperatures as hot as 50 °C.
As plants and animals adapted to this cocktail of evolutionary pressures, dryland springs and oases became home to unique flora and fauna found nowhere else on earth. For Renee, the most exquisite example of this is the Byarri – Edgbaston springs in central Queensland. There, a complex of nearly 300 GAB-fed springs offers refuge to a menagerie of native amphibians, reptiles, molluscs, crustaceans and fish, including 37 species unique to these springs. “It’s the jewel in the crown of global wetland biodiversity,” she says.
Top: Satellite image of Edgbaston Reserve (via maps.dea.ga.gov.au)
Bottom: Critically endangered red-finned blue-eyed fish, found in the springs at Edgbaston Reserve (image credit: Adam Kerezy)
Crucial lifelines and troubled waters
Springs and oases have played a crucial role in human evolution and prehistory around the world, as migrations across arid regions were both aided and constrained by the availability of fresh water.
Where artesian springs emerged and oases formed in harsh deserts, they offered water, shelter, as well as opportunities to fish, hunt, and seek out edible plants. They enabled populations to expand across continents and became crucial to trade routes. Time and again, they were woven into sacred mythologies and cultural histories. Some became sacred gathering sites, while others became hubs of agriculture and long-term settlement.
The springs and oases of Australia’s drylands certainly played an important role in the survival and migration of Australia’s First Peoples after they arrived on the continent more than 65,000 years ago. As such, they became places of great cultural and spiritual significance, featuring in songlines, ancient trade routes, sacred rituals and Indigenous knowledge systems.
The Bidalinha spring (also known as ‘The Bubbler’ spring) is part of the Wabma Kadarbu mound springs in South Australia. These springs have important cultural and spiritual significance to the First People of the area, and feature in their ancestral myths. The Wabma Kadarbu springs are part of the Oodnadatta Track which was used by the Kuyani, Arabana and Arrernte peoples. It follows a string of artesian springs across the desert. It was considered the only survivable way to cross the region and became an important trade route (image: Adobe stock)
When European settlers arrived in Australia and learned about the inland springs, they became curious about the groundwater systems in the Great Artesian Basin, Rod explains that it wasn’t long before they began drilling boreholes to access water for agriculture. His analogy, likening the underground aquifer to a water balloon covered by a blanket, is important for understanding what happened next.
“They started drilling holes that penetrated the blanket and got through to the balloon,” he says. “The water came out under a massive amount of pressure.”
“Before long there were thousands of these pinpricks in the balloon and thousands of kilometres of drains weaving their way around the landscape.”
This brought water to many dry parts of Queensland, bolstering the pastoral economy, but all those boreholes reduced water pressure in the aquifer, and many natural springs disappeared. Rod and his colleagues have quantified the springs of the GAB and discovered that about 50% of the springs are either totally or partially inactive due to the loss of pressure.
“The exploitation of the aquifer through bores is undoubtedly the major threat for the springs,” he says. This is harming ecosystem health and jeopardising a vital cultural connection to Country.
Great Artesian Basin: recharge areas are indicated by light blue and Spring Supergroups are represented by dashed envelopes. Generalised flow paths are indicated in red. Blue dots represent bores with artesian pressure above the ground surface and pre-1896 bores are highlighted in yellow. Source: Fensham and Laffineour (2025) https://doi.org/10.1016/j.jhydrol.2025.133726)
Spring extinction is not just a problem in Australia. Around the world, springs and oases are under threat from aquifer drawdown and other forms of human modification, as well as reduced rainfall and invasive species. Consequently, the incredibly diverse ecosystems that rely on dryland springs are now among the most threatened on the planet. In many cases, springs support longstanding agro-ecosystems which are interwoven with rich histories, cultural heritage and language diversity. As the springs are lost, these too come under threat.
Reasons to be hopeful
There is good news, though. In the GAB, bore-capping initiatives designed to conserve water and restore aquifer pressure appear to be working. There are cases where spring-fed wetlands that had been shrinking have begun to expand after nearby bores were capped.
A few years ago, Rod founded The Fellowship of the Spring. It’s a global initiative to study and protect the world’s springs and oases and comprises dozens of ground water experts from all around the world, including geologists, hydrologists, biologists, as well as anthropologists and archaeologists. Together they are systematically mapping the world’s dryland springs and oases, characterising the hydrology and biodiversity, and studying their cultural value. They are documenting what has been lost and they’re working to protect what remains. By studying the hydrogeology and cultural histories of springs and oases, they’re working to identify sustainable groundwater management practices.
Town Al Qasr at Dakhla Oasis in Egypt (image credit: Zdenar Adamsen via Adobe)
Rod is pleased to report that the Fellowship of the Spring is growing and that collaborative networks are emerging between all the members. “Our ambition is to basically help each other,” he says. “I’m really hopeful that we can extend this network, build on our work and get really good things happening around the world.”
Click here to watch the full TERN webinar
Lifelines in the Desert: the critical role of oases in biodiversity and heritage
Feature image: Dalhousie Springs (credit: Kirrily Blaylock)