After a year of rain, towns at the end of Australia’s giant river system await the slow, inevitable deluge

Some 4,000 properties and 200 businesses lie in the path of the water, as do Aboriginal burial grounds. The earth is saturated, and the water has nowhere to go

An enormous levee runs down Mannum’s main street. As the flood waters pour into South Australia from the eastern states, the river side of the town will be sacrificed. The other side, it is hoped, will be saved by the “great wall of Mannum”.

The water has come a long way, over many months, on rivers that flow from more than 1,500km north across the Queensland border, and from almost 1,000km east in the Snowy Mountains on the border of New South Wales and Victoria.

The devastating floods in those states have taken lives, and livelihoods, throughout the year.

Intense rainfall and storms first hit the east coast, filling rivers, lakes and dams and destroying homes, towns and businesses. More than 20 people died in February and March, when the damage was largely on the eastern side of the Great Dividing Range.

But the rain and the waves of floods kept coming, spreading gradually west and south later in the year, with recovering communities hit again in November. The earth is saturated, and the water has nowhere to go, and so it continues its inexorable path through the Murray-Darling Basin. For South Australia, it’s become an inevitable, slow-moving natural disaster, the premier, Peter Malinauskas, says.

Dozens of homes and two caravan parks were evacuated on Christmas Day as the flood levees failed along the river. About 4,000 properties across the length of the river are expected to be inundated and more than 1,100 have been flooded so far.

A levee down the middle of Mannum’s main street
A levee down the middle of Mannum’s main street. Photograph: Sia Duff/The Guardian

The Murray-Darling Basin is Australia’s biggest river system, spanning more than a million square kilometres. Parts of it were formed when Australia was part of Gondwana; others when Australia and Antarctica split from India. Huge, shallow depressions formed in this ancient landscape, over the Great Artesian Basin, which lies under much of today’s system.

On a map, the basin’s waterways form an arterial-like system. Smaller tributaries from southern Queensland, eastern NSW and northern Victoria feed into bigger and bigger rivers; eventually, the Murray and the Darling and, in the end, just the Murray.

The Murray-Darling river system

In Queensland, a “rain bomb” in February sent a “wall of water” gushing through the Weir, the Macintyre and other rivers, which cross the NSW border and merge to become the Barwon, which the Namoi joins a bit further down. Further north, a different network fuelled the Culgoa, which merges with the Barwon near Bourke, to become the Darling.

Rain pummelled parts of NSW and the ACT throughout the year. Residents around Gunnedah in NSW have endured nine floods in six months. Rain around Yass and Canberra fed the Murrumbidgee, and the water flowed through Wagga Wagga and Hay before joining the Lachlan. Meanwhile, in Victoria, the Murray picked up water through Echuca and Swan Hill, heading to meet the Murrumbidgee east of Mildura.

Flooding in Renmark, South Australia, in November
Flooding in Renmark, South Australia in November. Photograph: nearmap

Aboriginal burial grounds under threat

“Those two big river systems are in flood – the Darling and the Murray,” says Prof Richard Kingsford, a river ecologist and conservation biologist at the University of New South Wales.

“We’re talking about water coming in from east of Albury and right down around Shepparton, from Canberra through to Yass, then Forbes water is also getting through.

“That’s joining the River Murray from the Murrumbidgee.”

The water kept coming. That “Forbes water” is from the scene of November’s devastating floods, when the Lachlan in NSW reached historic heights. Farmers around Hillston have been isolated by water for months on end.

The Lachlan was fed in part by Mandagery Creek, which was the source of deadly flash flooding in Eugowra the same month.

One of the many vehicles swept away during a flash flood in the town of Eugowra, Central West New South Wales, Tuesday, November 15, 2022. (AAP Image/Murray McCloskey) NO ARCHIVING
One of the many vehicles swept away during a flash flood in the town of Eugowra, central west NSW in mid November. Photograph: Murray Mccloskey/AAP

While residents tried sandbagging to halt the inland tsunami, more rain kept hitting the sodden ground, and the rivers kept swelling.

“Then you get this image of the Darling meeting the Murray at Wentworth, and it’s amazing to see – the brown water meeting the less brown water,” Kingsford says.

“The big river, the Murray, and the smaller, the Darling, which has come in from way up north around Toowoomba and Goondiwindi.

“That’s filling up the Menindee lakes. Then the two meet, and the river flows into the River Murray at Wentworth.”

Lake Menindee at sunset
Lake Menindee at sunset in May. Photograph: Mike Bowers/The Guardian

The water keeps coming, spreading across floodplains, which slow it down for a while.

“Then it comes together, south west of Berri, becoming a single river channel again,” Kingsford says.

Up to 220 gigalitres a day will be funnelled into SA, with the peak set to cross the border over Christmas. Then it will take three weeks to travel through towns including Renmark, Waikerie and Mannum before, almost a year after those initial soaking rains, it will flow into the Great Australian Bight.

The water has been rising slowly and steadily – and sometimes quickly and unpredictably – for weeks in SA. Of the thousands of homes set to be inundated, many are shacks or holiday homes. Of those who live on the river, many have evacuated. There’s hope a system of levees – private, agricultural and government-built – will save whatever is still there.

Mannum’s flood marker
Flood-level indicators in Mannum earlier this month. Photograph: Sia Duff/The Guardian

But eight of those levees have already been breached – leaving one town isolated and wiping out the caravan park in another – and more than 50 need repairs.

And even though the months-long preparation will save lives, many valuable things will be destroyed.

Aboriginal burial grounds, scar trees and rock shelters are among at least 700 cultural heritage sites in the path of the water.

State government modelling shows more than 200 businesses and 4,000 hectares of agricultural land, including vineyards and orchards, will also be hit. This week all recreational activity on the river was banned, damaging the already hard-hit tourism industry.

A wallaby runs in floodwaters from the swollen Lachlan River as it began to inundate low lying areas of South Forbes
A wallaby runs in flood waters from the swollen Lachlan River in South Forbes. Photograph: Mike Bowers/The Guardian

There is a positive side. The enormous amount of water is flushing out the river system, which has been scarred by drought, including the terrible millennium drought. This has prompted the formation of the Murray Darling Basin plan, which was intended to help the river’s environmental health by preventing too much water being used for farming and irrigation further north and east, but which has been racked with bitter disputes.

Now, the deluge is flushing out the salt, and for the first time in decades the Murray mouth is open without the need for dredging. Barrages installed to keep the sea water out have been opened to let the fresh water through.

Malinauskas told the ABC on Wednesday that, while it’s difficult to talk about with the imminent “human tragedy”, the water will also bring “profound environmental benefits” through the scouring of the Murray mouth and the flow of water into the Coorong wetlands ecosystem, a priceless haven of diversity for plants and animals.

‘We’ll have one hell of a reopening party’

Back in Mannum, the Mid Murray mayor, Simone Bailey, says the town has been preparing for months and is “totally prepared” for the peak. And “most” residents are ready, she says.

“In September, probably 50% of our region didn’t believe it was going to happen. If you ask people in Mannum now, it’s real.”

Mannum mayor Simone Bailey
The Mannum mayor, Simone Bailey. Photograph: Sia Duff/The Guardian

Murraylands locals Ryan Hinds and Darren Smith, part of the team that built the great wall of Mannum, have drawn lines on the levee, bets on how high the water will get – almost to the top. Across the road at the Mannum Hotel, others are more pessimistic. They have drawn lines that reach to the pub roof.

Mannum’s great wall has taken a detour to incorporate the riverside Pretoria Hotel. But inside the bottle shop, you can hear the water in the basement, and the pub was forced to shut just before Christmas.

Riverland locals Ryan Hinds (left) and Darren Smith who helped build the levee
Riverland locals Ryan Hinds (left) and Darren Smith who helped build the town’s levee. Photograph: Sia Duff/The Guardian

On the pub’s last day, the venue manager, Brad Harper, is surprisingly chipper, if somewhat distracted. “The support has been unreal,” he says. Locals and interstaters have all pitched in with words and cash.

Normally, Harper says, this would be peak season and the river would be packed with recreational users.

“There’d be skiing, wakeboarding, jetskis. We’d have half a dozen houseboats parked out there, and 300 people on the lawn.”

Harper points towards the lawn, now a sunken courtyard with the red dirt levee looming, holding back the glinting water beyond.

“We’ll get back in. And we’ll have one hell of a reopening party,” he says.

Assistant manager of the Pretoria Hotel, Emeilia Tracey, letting people know it’s the last day of trading before the floodwaters close the business.
The assistant manager of the Pretoria Hotel, Emeilia Tracey, letting people know it’s the last day of trading before the flood waters close the business. Photograph: Sia Duff/The Guardian

But he concedes that could take months, and in the meantime the Bureau of Meteorology’s long-range forecast warns that “rivers are high, dams are full, and catchments are wet across much of eastern Australia, meaning any rainfall has the potential to lead to widespread flooding”.

While Mannum is preparing for the recovery even as it waits for the water to peak, Bailey looks out at the flood marker showing the history of inundation in the town.

It’s partially submerged, on the wrong side of the great wall.

“We do need to have a look at weather patterns,” Bailey says.

“And ask whether this is going to happen again next year.”


Tory Shepherd

The GuardianTramp

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