'People on rooftops' as Australians flee rising floodwaters

That's despite authorities warning people to stay out of the floodwater, because well, there might be sharks lurking underneath - if the threat of drowning in fast moving water wasn't enough of a threat.

Meanwhile, Prime Minister Malcolm Turnbull is urging flood-affected residents to be careful following the deaths of two women as waters sweep through northern NSW and southeast Queensland.

Wading through flooded areas can be unsafe anywhere in the world, but in Australia the waters may contain snakes, crocodiles and sharks as well as rubbish and sewage.

Cyclone Debbie, a category four storm, one short of the most powerful level five, pounded Queensland state on Tuesday, smashing tourist resorts, bringing down power lines and shutting down coal mines, has become a huge rain depression.

Mr Kim said the 30 litre containers he filled up would last about two days.

Local residents, churches, community groups as well as the Army, Police and SES have begun the slow cleanup in centres such as Airlie Beach, Shute Harbour and Proserpine, as well as offshore islands Hamilton, Hayman and Daydream which were hit hard.

The Bureau of Meteorology said that between 500 and 740 millimetres of rain had fallen in the middle and upper reaches of the Tweed River Valley in the 24 hours to 2am on Friday.

"They're there to protect life, and everybody: if you think something looks safe, you can not underestimate what's going on below the surface", she said.

The rain has been caused by remnants of ex-tropical cyclone Debbie clashing with a cold front.

Australia is home to 20 of the world's 25 most venomous snakes, including the entire top 10.

He said water mains had been destroyed, along with waste-treatment plants, with reports the Byrrill Creek Bridge had been washed away.

"The CBD is being flooded and because it's now very dark and it's also windy, there are a lot of people who're scared as well", former Lismore mayor Jenny Dowell told the ABC.Tens of thousands of people in the affected areas are without electricity.

Authorities fear more people may have died overnight as floodwaters continued to rise.

The Department of Education did send out text messages to all parents in southeast and central Queensland warning of the closure, but they were not sent until 10am, The Courier-Mail reported.

"We're anticipating 323 properties right across the city that will have had some kind of flooding - 211 homes that will be inundated - but of course it's wait and see".

  • Leroy Wright