Alltrikes

Two Australian states are bracing for a peak in floodwaters following the deadly aftermath of ex-cyclone Oswald.

Four people were killed in Queensland, where about 7500 people have been displaced in Bundaberg as the city contemplated a long recovery from its worst-ever flood disaster.

State Premier Campbell Newman toured the stricken city by air this morning and said he was shocked by what he saw.

''I've seen perhaps even more extraordinary sights than we saw two years ago in southeast Queensland.''

Australia's defence force has sent in two C130 heavy transport planes to help evacuate all patients at the local hospital.

The Burnett River was flowing at 9.4 metres and was expected to climb to 9.5m later today or tomorrow. That is lower than the 10m previously predicted but still half a metre higher than the 1942 record.

Floodwaters have reached the rooftops of more than a hundred businesses in the CBD of the southern Queensland town of Gympie.

About 25 homes have been also been affected by flooding, but it was not known if water had entered living areas.

The Mary River peaked at the major flood level of 20.3 metres on Monday afternoon, but was taking its time to recede and remained at a major flood level of 17.4 metres.

Water was continuing to swamp businesses in the heart of town.

Gympie Mayor Ron Dyne said locals were well versed in.

''They're emotional but they're down there working with the fire brigade to clean up the businesses.''

The Clarence River at Grafton appeared to have peaked just two centimetres below the top of the levee wall in the flood-hit northern NSW town.

Sam Colwell of the Clarence-Nambucca State Emergency Service said the river had hit a record level of 8.08 metres.

''It's looking reasonably safe at this stage. Even if did overtop in some places, there's a tiny bit of extra room on the freeboard, so it's just a little trickle, not catastrophic,'' she said.

The levee was breached along some parts of the wall but Clarence Valley Mayor Richie Williamson said council workers contained it with sandbags and were now concentrating on towns downstream.

It was the fourth time the Clarence had flooded in the past four years.

''This is a sight that has never been seen by white man. The Clarence has never been recorded above 7.9 metres, it's an awesome spectacle and still a very dangerous thing,'' Williamson said.

With the river rising upstream, more than 1000 people were issued an evacuation order this morning. They joined more than 1500 people who were told to leave yesterday.

Brisbane appeared to have escaped more flooding today, with river flood gauges at 11am (3pm NZT) sitting around the two-metre mark and were not expected to rise higher than 2.3m, slightly lower than the projected 2.6m peak.