Hazard reduction burning did not always stop the unprecedented 2019-20 bushfires from spreading, a royal commission has been told.
State and territory agencies say prescribed burning did have an impact on reducing the spread or intensity of the bushfires in many cases, but did not seem to even pause the fire in others.
NSW authorities said on Wednesday while the analysis into fire behaviour during the 2019-20 season was ongoing, recent fire activity in an area did not always stop a fire from spreading in the way that would ordinarily have been expected.
“We have some good examples where prescribed burning did have an impact on the fires that impacted in 2019-20,” NSW National Parks and Wildlife Service senior manager Naomi Stephens said.
But we certainly have situations where we would have expected that recent burns would have had more of an impact on the spread of the wildfire.’’
The 2019-20 bushfires, which burned an estimated 35 million hectares of land across Australia, sparked renewed debate about the effectiveness of prescribed or planned burning undertaken before the fire season.
Faced with criticism that not enough hazard reduction work was done in national parks, NSW Rural Fire Service commissioner Rob Rogers accepted there were lessons to be learnt from the last fire season.
“I don’t think from a NSW perspective that we’re saying that everything we do is great and there’s nothing more to do here,” Mr Rogers told the bushfires royal commission on Wednesday.
He said the quality of the hazard reduction work would be examined.
“In the last fire seasons sometimes hazard reductions work really well. Sometimes they really didn’t even seem to pause the fire,” Mr Rogers said.
The South Australian Country Fire Service’s Brett Loughlin said the state’s six major bushfires all occurred under catastrophic or extreme fire conditions, which limited the impact of hazard reduction activities.
“Where we saw at multiple times simultaneously half of our state under catastrophic fire danger index … the effects of fuel management and things like that is minimised by the severity of those conditions,” he said.
Mr Loughlin said there were some pretty good successes, given there were thousands of fire incidents across the season.
The states and territories use hazard reduction burning as a primary tool in their bushfire mitigation “armoury”, although the royal commission was told there was no one-size-fits-all approach.
Mr Rogers said the serious health impacts of hazard reduction burns, including through smoke causing premature deaths, and what the community would tolerate also needed to be taken into account.
“We get as a state accused of not doing enough hazard reduction but then when we do hazard reduction, often in Sydney areas or the surrounds of Sydney, it smokes out Sydney.”
Ms Stephens defended the National Parks and Wildlife Service’s hazard reduction work, saying it had undertaken 137,000 hectares of burning each year over the past seven years and had a good record of containing fires that burnt in its parks.