There are concerns prevailing drought conditions will result in an increase in dust storms and thunderstorm activity, potentially outdoing Victoria and NSW’s dustiest December on record.
Community DustWatch co-ordinator Dr John Leys said strong winds, coupled with the drought and loss of ground cover, led to the increased dust storm activity, which hit the eastern seaboard in recent weeks.
“While weather systems change, in December it was windier than the 10-year average,” Dr Leys said.
He said there were large areas in the Mallee and North Central Catchment Management Authorities where ground cover had dropped by between 20 and 40 per cent, from September to December.
In DustWatch’s NSW section, there were 30pc more winds recorded at more than 40 kilometres an hour.
Dr Leys said the trend was likely to have continued into January.
“Predicting dust storms is pretty difficult but it’s increasingly likely there will be more of them,” he said.
“Under climate change, the ‘dries’ are going to get drier, and the ‘wets’ are going to get wetter. There will be longer, hotter droughts – that’s a plus for causing dust storms – but land management is getting better.”
Predicting dust storms is pretty difficult but it’s increasingly likely there will be more of them.
Practices such as rotational grazing, chemical fallowing and crop residue maintenance meant farmers were more aware of how to control soil erosion than ever before.
“In a 2004 report on dust storm activity in eastern Australia, we found there were six times fewer events in the Millenium drought than in the 1940s,” he said.
Community volunteers at about 40 monitoring stations in southern Australia record data and observations about dust in their local areas.
Victoria has five monitoring stations, at Buronga, Werrimull, Walpeup, Wycheproof and Loddon Plains.
Dr Leys said the DustWatch initiative had provided a better understanding of the causes and costs of dust storms, leading natural resource agencies to increase their investment in ground cover projects across Australia.
He said the big unknown was wind.
“Spring is windy, so we get really big dust storms then, but by autumn the wind speeds start to drop,” he said.
The recent dust storms in Victoria and NSW could also have been caused by lack of ground cover, due to a failed crop, paddocks that were grazed too hard, or fire, caused by lightning strikes.
Dr Leys said the most significant impact from dust storms was not on lost productivity on-farm, but in the cities.
He said the ‘Red Dawn’, which hit Sydney on September 23, 2009, was estimated to have cost $300 million in lost productivity.
Last week’s Northern Victorian dust storm occurred nearly 36 years ago to the day that Melbourne was enveloped in red soil, dust and sand from the Mallee.
On February 8, 1983, Melbourne was hit by high winds, carrying loose topsoil, from the Mallee and Wimmera.
Dr Leys said there was also the cost of cleaning up, transport shutdowns, health impacts and even the effect on building sites, which had to close due to occupational health and safety issues.
“When a landholder carries out good land management practices, he helps the rest of the community,” he said.
Bureau of Meteorology forecaster Chris Arvier said last week’s dust storm, which affected Durham Ox and Kerang, resulted from a trough, which moved through the state.
“This one was generated by some very strong, gusty outflows from storms, which passed through the state,” Mr Arvier said.
“The atmosphere was primed for storm activity.
“It was very humid, there was a low pressure trough moving through Victoria, at surface level, with an unstable atmosphere above.”
Ashley Gould, who saw last week’s storm first hand, was working near Durham Ox, on Murray Haw’s sheep property.
“The dust storm was coming in from the North-West, out of the Mallee,” Mr Gould said.
“It rolled up through Pyramid Hill, you could see it everywhere you looked.
“For about 10-15 minutes, it was really windy.”
Drew Chislett, Durham Ox, said the dust storm rolled over at around four o’clock.
“It was just spectacular, you couldn’t see 15 metres in front of yourself,” Mr Chislett said.
“It’s rare to see such a spectacular dust storm these days, due to the changes in farming practices. But when it does come, it just looks like a big angry monster.”