Dust storms here to stay
Tuesday, 21st January, 2020
By Callum Marshall
With dust storms sweeping across the Central and Far West, a soil scientist at the University of Sydney has warned that they will become more episodic and less predictable during periods of short, sharp erratic droughts.
Associate Professor Stephen Cattle of the Sydney Institute of Agriculture told the BDT climate change will have an indirect effect on the prevalence of dust storms behaviour.
“Having been to Broken Hill numerous times before, it’s a dusty place because it’s part of the arid zone of the Far West division so it’s always going to be dry and dusty out there to a certain extent,” said Professor Cattle.
“I think it’s going to affect south-eastern Australia where it becomes more erratic with regard to rainfall and when it comes to temperature fluctuations.
“That’s going to have a knock-on effect of getting periods like in 2009 when we had the Red Dawn dust event that got all the way to Sydney.”
He said that came at the end of the Millennium Drought and was followed by the two wettest years in the country and Broken Hill’s history: 2010 and 2011.
Erratic fluctuations between dry and wet periods could lead to intense dust storm activity during times of drought, he said.
“I think we can expect to see more of the same in the future where we see very erratic short, sharp severe droughts and then we might have a couple of years of very good rainfall and maybe some ‘average’ weather.
“That should become the more norm of the situation - it’s going to be irregular and erratic and unpredictable.
“If that’s the case then we can expect from time to time some pretty intense dust storm activity.”
Assoc. Prof Cattle said water extraction that has dried up rivers and lakes was not associated with the dust storms.
“The dust source area is not a floodplain nor is it the Darling River itself,” he said.
“It’s areas that are west. All the plains out to the west, there’s no vegetative cover.
“They’re the ones that are blowing in the Lake Eyre Basin and Mallee, part of North-west Victoria.
“Certainly, the management of the water supply down the Murray-Darling Basin is going to severely impact on agriculture, viticulture and horticulture in those lower parts of the basin.”
He said that the Federation Drought of 1895 to 1902 highlighted that significant impact on the land could occur without having to factor in things like water extraction.
“In the Western division then there was something like 15 million sheep at the start (of the drought) and only four million left at the end, so it knocked out three quarters of the sheep flock.
“There are all these pictures of horrendously wind-eroded landscapes and it was just horrible because there’s no rain and lots of wind and it’s very hot.
“People weren’t using water from the Darling River for irrigation then, but there was still calamitous dust storms.”
What was helping now were better land management practices, he said, although even then they can only do so much when up against nature.
“A hundred years ago, the Western division was overstocked with sheep,” said Assoc Prof Cattle.
“There were rabbit plagues happening, lots of mouths to eat all the grass away and to expose the soil, whereas now our understanding of land management in the arid zone is much better.
“People understand, generally, that you’ve got to keep ground cover wherever possible. But sometimes nature is just too good (with the) winds.”
Overall, he said, people should prepare for more erratic weather.
“Graziers and croppers have to make hay when the sun shines and the rain falls,” said Assoc Prof Cattle.
“When it’s hot and dry they’ve just got to batten down the hatches and get through it.
“It’s going to be the new norm in agriculture at least.
“You’ve just got accept the fact that some years it’s not going to be good for growing anything, and other years, when it is good, you’re going to have to absolutely go for it and produce, produce, produce.”