Record flooding across northern New South Wales will force Lismore shire council to rework its new flood management strategy even before it is implemented, and other regions will probably follow suit as insurers tally the cost of worsening climate extremes.
Lismore’s mayor, Steve Krieg, just 10 weeks into the role, says his town is struggling to cope with hundreds of emergency calls. He says the council will need to revisit plans to lift the area’s levee banks after the Wilsons River peaked on Monday afternoon at 14.4m, topping the previous records by 2m.
“I think we’re going to have to redo a lot of things,” Krieg said. “There were a lot of decisions made in the past that probably weren’t in the best interest of the city as a whole.
“In the coming weeks and months, we will be definitely implementing a much stronger and a much sturdier flood plain management strategy,” he said, adding that the priority for the moment was “all about saving lives”.
Large areas of south-eastern Queensland, including parts of Brisbane, were busy assessing damage from days of heavy rain and severe flooding.
That weather system, dubbed a “rain bomb”, shifted south into northern NSW bringing record flooding to Lismore and other towns, and parts of Sydney may be exposed to floods within days.
Dunoon, a village near Lismore and Australia’s self-proclaimed macadamia capital, collected 775mm of rain in the 24 hours to 9am Monday, the second-highest daily total on record for NSW, said a Weatherzone meteorologist, Ben Domensino.
NSW's Wilson River at Lismore remains near its record peak level above 14m. @BOM_NSW pic.twitter.com/06I3tqu6gb
— Peter Hannam (@p_hannam) February 28, 2022
The Insurance Council of Australia on Monday said almost 15,000 insurance claims had already been lodged. It also extended the area declared an insurance catastrophe from south-east Queensland into northern NSW to help prioritise claims handling.
The deluge and flooding prompted the council to suspend a campaign launched a week ago to encourage the winner of this year’s federal election to spend more on building resilience to severe weather events, which are only predicted to worsen as the climate heats up.
“Unfortunately, the extreme weather being experienced in Queensland and New South Wales is a sombre reminder of why governments need to do more to better protect communities from the impacts of these events,” Andrew Hall, the council’s chief executive, told Guardian Australia.
“That’s why we called for the federal government to double funding in measures that better protect homes and communities to $200m per year, and for this to be matched by the states and territories.”
Among theInsurance Council’s recommendations to make Australia more resilient was a $522m local infrastructure fund for projects such as flood levees to defend regional towns. It also recommended a program to better protect homes against flooding and an improved national flood warning system to increase the lead time for warnings from three to five days to 10 to 15 days.
Andrew Gissing, general manager of consulting firm Risk Frontiers, said a warming atmosphere holds more moisture – at the rate of 7% per degree of heating – bringing the potential for more intense rainfall.
“So that’ll have an impact on the frequency of flooding in the future,” Gissing said. “Rising sea levels will increase flooding in estuarine areas as well.”
Flood damage is expected to increase in the coming days, with rivers such as the Clarence still rising, putting at risk Grafton and other towns. Further south, WaterNSW was predicting Sydney’s Warragamba Dam would start spilling later this week as heavy rains tops up a reservoir already near capacity.
The Bureau of Meteorology forecasts Sydney will be soaked with 40mm to 70mm of rainfall on Tuesday, 60mm to 90mm on Wednesday and 20mm to 35mm on Thursday. Inland regions, such as Warragamba, are not expected to get as much rain as coastal areas but falls will be enough to have multiple dams spilling, WaterNSW said.
Gissing said it may take a week or longer for flood waters to drain off and the full extent of the damage to homes, businesses and infrastructure to be known.
He noted that Lismore’s new flood plan had only envisaged lifting the levee protecting the central business district to cope with a one-in-20-year flood, rather than the historic flood that has devastated the town.
To cope with a flood like the current one, the levee “would actually have to be pretty enormous”, Gissing said. “Whether or not that would actually be physically possible or actually acceptable to the community [is the question].”
The fact the flooding at Lismore is unprecedented doesn’t mean it should not have been predicted, he said, adding that engineering increasingly takes into account the scale of potential flooding in a catchment, not just the historical record.
And the climate crisis means those predictions will need refining as climate models improve.
“We know that heavy rain’s more likely in the future, and that our sea levels are going to rise further, which means coastal flooding is going to be an even bigger problem, and we continue to want to develop on flood-prone land” Gissing said. “So we’re continuing to increase the level of exposure that our communities have to flooding.”
