Protecting Australian towns from future environmental disasters has come under the spotlight at a meeting of New South Wales mayors.
The man who helped rebuild New Orleans after Hurricane Katrina has been speaking at a three-day forum in Sydney.
Edward Blakely, from the US Studies Centre at Sydney University, says Australians have been incorrectly allowed to build in bushfire and flood-prone areas like hills and on low-lying land.
He says all levels of government must replicate California's example, where at-risk areas have been turned into public space.
"The government just says, 'If you sell your property, you sell it to me,' or 'You can stay exactly where you are, but we're not going to give you an incentive to transfer it to somebody else and put them in danger'," he said.
"We wouldn't have any roads if the government didn't condemn property for them; the government expropriated that land and there was somebody living on it, somebody dwelling on it."
Mr Blakely says allowing residents to live anywhere they want risks entire communities in the event of bushfires and floods.
"It would be nice if they were the only ones that were at risk, but every time you build in a fire zone we put a fire person at risk; we put all the rescue and emergency people at risk," he said.
© ABC 2013
12:52 EST A thick northwest cloudband has brought the best rain in over a year to parts of inland South Australia.