Supplies flown into Queensland's flooded Rockhampton
Military aircraft are flying supplies into the Australian city of Rockhampton, where rising flood waters have cut off all but one access route.
Waters have been gradually submerging parts of the city of 77,000.
More than 20 towns in Queensland have been cut off or flooded across an area larger than France and Germany, with more than 200,000 people affected.
Authorities have now confirmed three deaths caused by flood waters in the past few days.
Officials have said that the crisis could last another month.
"Given the scale and size of this disaster and the prospect that we'll see waters sitting for potentially a couple of weeks... we will continue to have major issues to deal with throughout January," said Queensland Premier Anna Bligh.
Rockhampton has already been badly hit, leading many of its inhabitants to flee.
The city's airport, a major regional hub, was closed to commercial traffic due to flooded runways, while many main roads and railways into the area have been cut off, and power supplies disrupted.
"Today we'll see resupply of Rockhampton by military aircraft taking supplies into Mackay and then road transporting them down to Rockhampton," the state's emergency coordinator, police Deputy Commissioner Ian Stewart, said on Monday.
"That will continue until such time as the road is cut."
The water level in the Fitzroy River is expected to reach nine metres (30 feet) on Monday and peak at 9.4 metres on Wednesday, threatening as many as 4,000 homes.
One Rockhampton resident told the BBC there had been panic-buying in the city.
"Lots of people have been stocking up on fuel. I also heard about one woman who brought 20 loaves of bread from a supermarket," said the resident, Petros Khalesirad.
Rockhampton Mayor Brad Carter has said about 40% of the city could be affected, and warned the floods had swept snakes downstream.
"Snakes have been swimming at people's feet as they make their way through the waters," he said. "I know one guy who killed four snakes this morning, one of which was a Taipan - the more it bites, the more it injects venom that could easily kill."
The intense rains have also had an impact on two of the country's principle exports - wheat and coal.
More than 50 ships were unable to dock at the major Queensland coal port of Dalrymple while some 18 more were waiting outside the port of Gladstone, which was operating at greatly reduced capacity.
As much as half of the country's wheat crop - some 10 million tonnes - have been downgraded to less than milling quality due to the flood damage, Reuters reports. The country is the world's fourth largest exporter of the crop.
Also on Monday, two more deaths from the flooding were confirmed.
One was a 38-year-old man whose boat was swamped near the mouth of the Boyne River, and the other was a woman whose car was washed off the road west of Emerald.
On Sunday, another woman swept from the road while trying to cross the Leichhardt River became the first confirmed death as a result of recent flooding.
Meanwhile, Prime Minister Julia Gillard has announced that grants and low-interest loans would be made available to help local businesses recover from the flooding.
"This is a major natural disaster and recovery will take a significant amount of time," she said.
"The extent of flooding being experienced by Queensland is unprecedented and requires a national and united response."
However, forecasters cancelled a severe storm warning on Monday, saying the immediate threat had passed.