Geologists and First Nations eye ancient water in SA’s arid north

Getting a glass of water on a hot day in the dry northwest of South Australia can be a tough call.

And it won’t get any easier under climate change, given the frequency of droughts in Australia’s Outback is forecast to rise.

Summer temperatures already reach into the 40s there, and rainfall averages only 230mm per year, meaning remote Aboriginal settlements face the very real risk of running out of drinking water.

But there may be answers.

Water tens of millions of years old has been found in bedrock and ancient valleys deep below the sparsely populated Anangu Pitjantjatjara Yankuntjatjara (APY) Lands in the state’s north-west. And two new research projects starting this year aim to find out exactly how much of the water can be used.

The APY Lands

The Lands, as they are known, are home to about 2500 Aboriginal people living across 103,000 km2 of desert in settlements west of the Stuart Highway.

The main settlements of Amata, Fregon, Indulkana, Mimili, Pukatja and Yunyarinyi are among 19 scattered across the Lands and reaching across the West Australian border, a region where 90% of people speak Pitjantjatjara or Yankunytjatjara at home.

Geologically speaking, the region is called the Musgrave geological province, 120,000 km2 of ancient oceanic crust straddling the borders between South Australia, the Northern Territory and Western Australia.

Screenshot 2024 03 15 093635
Palaeovalley map of the APY lands, SA, shows the interpreted distribution of sediment-filled palaeovalleys hidden beneath the surface of modern day sandplains, dunefields and creeks. Courtesy of Government of SA. Dept Energy and Mining

In recent years, hydrogeological maps of the Lands were published in Pitjantjatjara in an Australian first to help spread water knowledge within the region.

Now, two projects announced in February will see water scientists partnering with local First Nations knowledge holders to further investigate the most promising sources.

Dubbed “climate resilient” water, it is thought such sources may remain relatively unaffected by forecast variations in rainfall and temperature under a changing climate.

What we already know

Many Aboriginal communities in the north of South Australia depend on rainwater for drinking supplies, others on low-yielding groundwater systems.

More reliable sources are needed, but not enough is known about the location, extent, and quality of suitable groundwater in the places where it is needed most. Indeed, hydrogeologic knowledge across much of Australia is poor.

Working together for better drinking water in the bush forum, 27-29 June 2023 from Goyder Institute on Vimeo.

In remote SA, however, the drinking water situation remains critical. Conversely, recent studies suggest Musgrave Province and the APY lands may have high groundwater potential.

Complicating this picture of watery opposites further, the SA Government has identified Musgrave Province as “an important frontier exploration area for further mining industry development in South Australia … a key priority area for exploration and mining development in the APY lands”.

In terms of what we know of the region’s water potential, key milestones must include the work of geologists Mark Pawley and Carmen Krapf of the SA Geological Survey, who, in a desktop assessment, probed the potential of bedrock aquifers under the APY Lands from which hydrogeological maps were published in 2016.

Mark pawley snr geologist geological survey of sa
Mark Pawley

Precious water: better knowledge needed

Using existing data, they tagged 17 potential water sources worthy of further investigation.

Then in 2021, CSIRO, Flinders University and the South Australian Government published work by senior CSIRO researchers Dr Tim Munday and Dr Mat Gilfedder investigating water sources underlying the Lands. Publication came under the auspices of the Goyder Institute for Water Research in a project called GFLOW, which aimed to “facilitate Outback water solutions”.

Under the Lands, the researchers identified water-bearing paleo-valleys tens of millions of years old, water that might support not only drinking water needs, but potentially mining and grazing.

“These valleys started to erode and form about 60 million years ago,” said Research Director Tim Munday in an interview for CSIRO at the time.

“For the last 5 million years they have been filled up with sediments and wind-blown sand and hidden from view. People have known about these valleys for a long time but knowing precisely where they are, has been more difficult.”

This year’s research

Scheduled for completion this year under the National Water Grid Fund, the first of two groundwater projects will assess the state of water sources currently in use on the Lands.

Researchers will drill, sample and test on those Aboriginal communities responsible for their own supplies of water and deemed most “at risk” for water security.

The $300,000 project will assess the existing aquifers’ characteristics through hydraulic testing and estimate longevity of supply.

Tim and friends
Tim Munday (left) and his team on the APY Lands. (Supplied)

A second project is aimed more broadly and hopes to build on the more recent studies.

A $2.5m partnership between APY Lands and SA water planners, and jointly funded by the Commonwealth ($1.9m) and the SA Government ($0.6m), the second project aims to sample and test new groundwater sources to assess their sustainability.

That means any new aquifers thought to have high yields and low salinity will be targeted for closer examination, especially where scarcity of water is affecting health and wellbeing, and stifling opportunities for economic development.

An innovative aspect of the projects will be an intended high level of community engagement, which hopes to engage APY stakeholders, recognise community-led water decisions, and work with traditional knowledges.

The Greenlight Project is a year-long look at how regional Australia is preparing for and adapting to climate change.

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