Australian news, and some related international items

Murray-Darling River system; mysterious loss of more than 2 trillion litres of water

The mystery of the Murray-Darling’s vanishing flows, ABC By national science, technology and environment reporter Michael SlezakMark DomanKatia Shatoba, Penny Timms and Alex Palmer 3 Sep 2020

It might be the biggest whodunnit — or what-dunnit — in Australia.

More than 2 trillion litres of water — enough to fill Sydney Harbour four and a half times — has gone missing from our largest and most precious river system — the Murray-Darling Basin.

And it’s happened in what was already one of the driest periods the basin has seen.

According to an investigation by some of Australia’s top water scientists, shared exclusively with the ABC, 20 per cent of the water expected to flow down the rivers from 2012-2019 was simply not there. That’s despite almost $7 billion being spent to protect the health of the system’s rivers and ecosystems that rely on them.

Was it stolen? Was it lost? Has climate change made it go up in steam? Or was it simply never there in the first place?

There are clues scattered up and down the rivers but one simple message is clear in the scientists’ findings. For the first time, they provide evidence that the Murray-Darling Basin Plan — the most expensive environmental program in Australia’s history — is delivering much less water than was expected.

And the implications could be huge……. EXCELLENT INTERACTIVE GRAPHICS HERE

…..“It’s a huge discrepancy to be missing a fifth of the water that’s meant to be in the rivers,” said Jamie Pittock from the ANU. He’s an expert in water management and a co-author of the Wentworth Group’s report.

“It means that there are all sorts of things that Australians value that won’t be sustained … like more water for towns … the floodplains, growing grass for sheep and cattle, in terms of biodiversity being conserved, waterbirds, red gum forests and conserving our fish.”…………

there are clues. Lots of them. We’ve seen water go missing up and down the river with clear explanations before. And looking closely at the new report, many of those explanations are consistent with the new data.

Clue one: tampered meters and criminal prosecutions

One possible explanation for the shortfall is that some of the missing water has been stolen.

An investigation by Four Corners in 2017 put water theft in the spotlight — much of it around the Barwon-Darling catchment in the Northern Basin.

Irrigators there, according to official figures, use 3 per cent of all the water taken from the entire Murray-Darling Basin.

But on top of those official figures, there has been significantly more water taken in that area. The Murray-Darling Basin Authority itself estimated that in the Northern Basin, as little as 25 per cent of surface water take has been metered.

Some of the water that went unmetered was stolen.

Peter Harris, who was named in the 2017 Four Corners, was this year found guilty of water theft just upstream from those gauges at Brewarrina.

Anthony Barlow, another person named in the program, was found guilty and fined $190,000, for water theft just upstream again.

Since the Natural Resources Access Regulator (NRAR) was formed in NSW in 2018, 15 additional charges have been laid in these locations across the state for water theft and related actions, according to an NRAR spokeswoman.

Emma Carmody, a lawyer at the Environmental Defenders’ Office, said the criminal prosecutions do not represent how widespread water theft has been.

“I’d actually go so far as to say that this situation pre-2018 was catastrophically bad in those northern catchments in relation to compliance and enforcement,” Dr Carmody said………..

Clue two: shadow take

Travel further upstream along the Macquarie River towards Dubbo, and you land in the internationally protected wetlands of the Macquarie Marshes………

In a landscape so flat, structures like roads, engineered channels and small levee banks can divert staggering volumes of floodwater — potentially shepherding it across a farmer’s fields where it is left to soak into the ground, or even pumped into dams.

This water taken by irrigators and graziers from the floodplains — rather than from the rivers — has hardly ever been measured.

Using satellite imagery, flood paths appear guided by seemingly innocuous structures, or completely cut off by others.

Richard Kingsford is a river ecologist at the University of New South Wales who has studied the Macquarie Marshes and the impacts of floodplain harvesting.

He says water that spills over floodplains often drains back into rivers, and interrupting its flow can have big impacts, including contributing to the missing flows.

“There are very few places where we have an accurate estimate of how much water is being taken from the floodplain. And to me, this has been a yawning gap in the policy,” he said…………

Clue Three: The cash splash

If we head all the way to southern NSW, we see a completely different clue.

Billions have been spent subsidising “efficiency measures” to help farmers save water there.

That can be done by upgrading old irrigation systems to deliver water directly to roots, or lining water channels, for example. Then about half of the water saved by the farmers gets handed to the government for the environment.

But according to some experts, the “inefficiencies” prior to the upgrades just meant some of the water used by irrigators flowed back into the rivers. The upgrades mean that “return flow” stops happening………..

In a report published in 2019, Professor Williams estimated that at least 280 billion litres of water per year might have been lost from the rivers — and are unaccounted for — due to this problem.

“That must be a major reason that we’re not getting the flow regimes that we need,” Professor Williams said.

The MDBA commissioned its own analysis of the issue and concluded the loss of return flows was reducing water in the rivers by 121 billion litres a year.……..

Clue Four: Climate change

There is one issue, however, that most experts do agree is a major reason for the missing water in the basin.

“The MDBA considers a changing climate to be the primary contributory factor,” said the MDBA’s Vicki Woodburn.

Since the basin plan was introduced, heat records across the area have been broken in four of the eight years. The last three years have been the hottest ever recorded in the basin.

According to the South Australian royal commission into the Murray-Darling basin plan, the MDBA “completely ignored climate change” when determining how much water needed to be saved.

If true, that means the overall target may have been set too low — that more water needs to be recovered from irrigation to save the river system.

But the same models used to set those targets have also been used to manage the rivers, and now to calculate how much water should be in the rivers. And by inadequately accounting for climate change, those models are likely over-predicting how much water is being recovered.

Climate change means more water is likely being lost between gauges, as it flows along — lost into the dry river beds and the hot air…………..

Clue five: The water was never there

In a twist worthy of any whodunnit, could it be that some of the missing water was simply never there in the first place?

According to the Wentworth Group, the government modelling used to predict how much water we should see in the river has some fundamental flaws which likely exaggerate the volumes.

For example, in 2018, the Murray-Darling Basin Authority found its modelling “has trouble predicting low flows”.

That meant that when water stopped flowing in the river, the model would still show water flowing — something that could have been particularly problematic over the past seven years when low flows were very common………….

What it all means

If there’s less water in the rivers than we ever planned for, what’s to be done about it?……………..

Professor Vertessy, who advises the MDBA, thinks this sort of shortfall could contribute to a rethink of the long-term water recovery targets.

“We may have to — I think everyone would accept that these sustainable diversion limits aren’t quantities which you ossify for posterity,” he says.

“They’ve got to be adjusted to fit in with the new climate realities and the social preferences of the day.”

And the scientists say whatever the response to the findings, something has to give.

“The current basin plan tries to pretend that we can do everything with a smaller and smaller cake,” says Professor Pittock.

“What this really means is that society is going to have to make some hard choices. How much irrigated agriculture do we want as a society versus how much do we want to retain by way of wetlands and ecosystems [or] of sites of cultural value to Indigenous people?”

September 3, 2020 - Posted by | AUSTRALIA - NATIONAL, environment

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