Research paints potentially dire picture of Murrumbidgee River

Macquarie University researchers have predicted the Murrumbidgee could stop flowing permanently into the Murray River without human intervention.

Their modelling suggests Australia's desert centre will spread outwards by 2070, well into the Murray-Darling Basin and Riverina farmlands.

Researcher Zacchary Larkin said the paper examined the way Australia's inland rivers would transform due to climate change as the continent becomes more dry and its findings were "stark".

"Results show the arid zone in central Australia is expected to expand quite considerably, and the humid zones around the Great Dividing Range are expected to contract quite a lot," Mr Larkin said.

"The Murrumbidgee has headwater catchments up in the Snowy Mountains. So if they get less rainfall there's less streamflow in the Australian rivers."

The modelling predicts a "moderate scenario" based on worldwide climate emissions peaking in 2040 and gradually declining from there.

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Mr Larkin stressed the results were not a guarantee and were instead a best estimate based on 16 different global climate models, which didn't take into account human ability to manipulate water.

"It's hard to know and there's lots of uncertainty," he said.

"The arid zone is expected to expand ... across quite a lot of the lower Murrumbidgee."

CSU social researcher Jonathon Howard said he would like to see river communities managed for resilience.

"The Murrumbidgee is a really vital food bowl ... it produces about $34 billion in agriculture each year and 53 per cent of the water that comes down the Murrumbidgee is extracted for use," Dr Howard said.

"What we're going to see with climate change is there'll be a decrease in flow by about a third which will mean we'll have to be more water efficient."

Dr Howard said people felt they didn't have a say in water planning, and that decision makers needed to consider climate change.

"It's interesting to see what governance systems are in place to try and adjust for this because we're seeing that some of the water ministers in NSW have not considered climate change in water planning," he said.

"We're getting allocations of water that are disproportionate for the amount of water available."

Murrumbidgee Field Naturalists President Alan Whitehead said he had seen soil aridity increase markedly over the past four years in Narrandera.

"Basically through Narrandera, that longitudinal line, there's a divisional line between the 500ml rainfall average and the 250ml rainfall average, which is further west. That line is moving," Mr Whitehead said.

"That was a known area among farmers and agriculturalists, that you could plant certain cereal crops on the eastern side, but not on the west. And now you can't even crop them most years on the eastern side either."