The recent flooding in south-east Queensland and northern New South Wales has been described as a hybrid of previous disasters, which offers lessons that might help avoid history repeating.
- Dr Cook said authorities needed to be proactive rather than reactive to floods
- She said their frequency and intensity will increase with climate change
- Brisbane’s Lord Mayor says he is prepared to make any changes necessary to improve
Margaret Cook is a lecturer at the University of the Sunshine Coast and an expert in the history of Australian natural disasters.
She said although the Brisbane and Ipswich rivers experienced flooding like in 2011, the suburban creeks “played an enormous part” like in 1974.
Heavy rain fell upstream of the Wivenhoe Dam in 2011, while last weekend the water flowed downstream of the dam and into creeks.
“This is why Brisbane got so badly affected this time, and lots of places got flooded on the weekend that didn’t flood in 2011,” she said.
Dr Cook said the quantity and intensity of the rainfall this week, combined with gentrification around creeks, were the main contributing factors.
“Floods are all about where the rain falls, how much of it falls and how quickly it falls,” she said.
“No stormwater or creek system can cope with that [amount of rain].
“The other problem is created by humans. If you look at where we’ve built in that time, we’ve built beside a lot of creeks. We’ve filled some creeks in. So we’ve actually interfered with the natural flow rates and the flow paths of creeks.”
Dr Cook said during natural cycles of floods and drought, flooding was more likely to occur during La Niña years like 2022.
“We will get more of them [floods]. The prediction is that these floods will become more frequent and more intense with climate change,” she said.
“But the good news is every time there is a flood, we get more information, we do learn more.
“We’re really quite good at cleaning up. But we’re really not good at preparing.”
What can be done differently?
After the 2011 floods, a Deloitte Access Economics report found 3 per cent of Australia’s disaster funds were put towards preventing disaster.
The other 97 per cent of the federal government’s expenditure went towards disaster recovery and repairs.
For a city built on a flood plain, Dr Cook said better land-use planning and “smarter” home designs were some preventative measures that could be taken.
“For example, concrete floors can be hosed out pretty easily, and hardwood furniture is much more resilient than plywood or timber veneers,” she said.
“So we can start by thinking about our building designs and by thinking about not making the problem worse.”
She said high population densities in cities put pressure on stormwater systems and the building of homes in flood plains compounded the problem.
“We really need to look at our planning codes about where we’re building,” she said.
Dr Cook said some new skyrises were now being built with their lift shaft mechanism in the roof as opposed to the basement.
“It might seem really small, but the people living in buildings at Tennyson couldn’t get back into their high-rises for six months after 2011 because the lifts didn’t work,” she said.
Dr Cook said retrofitting sewage systems and waterways to modern conditions was also needed and even though it was expensive, it could be done gradually.
“If they’re having to rebuild a road anyway, the whole road is dug up, maybe that’s an opportunity to fix the pipes underneath it,” she said.
Dr Cook said a public campaign on what to do in a flood should also be a priority, similar to education on fire preparedness.
“I’m a historian, I don’t want to see history keep repeating itself and some of this just does repeat itself every single time,” she said.
“We have the technology, we could use it better.
“We really do know where all the vulnerable spots are.
‘We’re open’ to improving
Brisbane Lord Mayor Adrian Schrinner said the city had a long history of dealing with floods.
“The story of Brisbane has always been a story that has had flooding in it and it’s about taking a risk-management approach,” he said.
Mr Schrinner said lessons have been learned from past weather events.
“There’s things that we can continue to do but there was a lot done after 2011 that has improved the situation,” he said.
“But we’re always open to working with the community, working with other levels of government to make any improvements that are necessary.”