|Food shortages are already affecting towns isolated by flooding, which has affected Queensland heavily [EPA]
Australian authorities say flooding in the country's northeast is a disaster of "biblical proportions".
Up to 200,000 people have been affected by the floods, which have hurt the nation's lucrative mining industry and cut off major highways as the water rushes through sodden inland regions to the sea.
Floodwaters continued to rise in parts of the state of Queensland on Saturday. Some communities are likely to be cut off for more than a week.
"In many ways, it is a disaster of biblical proportions," Andrew Fraser, the treasurer for the state of Queensland, said in flood-hit Bundaberg on Saturday.
The entire population of two towns has already been forced to evacuate as water swamped their communities, cutting off roads and devastating crops.
The next city in the water's path - Rockhampton, near the coast - is bracing for flood levels forecast at 9.4m by Wednesday.
Rockhampton airport closed to commercial flights on Saturday as flood waters continued to take hold in the central Queensland city.
Water creeping in
Road links were expected to be cut as water crept into low-lying parts of the community.
"The community is likely to be cut off for a period of 10 days from the south and through this airport," Brad Carter, the mayor of Rockhampton, said.
Carter warned about 40 per cent of the city could be affected when the Fitzroy river peaks.
Officials began evacuating residents on Friday, starting with the elderly and those living in low-lying areas.
There were concerns over food supplies in the city, with many stores already sold out of bread, milk and fresh meat.
Greg Goebel, the executive director of the Australian Red Cross, told Al Jazeera that some towns, isolated by the flooding, have already run out of food. Authorities are also concerned by the likelihood of the spread of diseases like dengue fever, as the extensive body of floodwater breeds mosquitoes.
"A number of towns are cut off, and they will be cut off for about three to four weeks. So a lot of the authorities are having the army drop in supplies," he said.
"In terms of waterborne diseases, the health authorities are monitoring this very closely. Queensland is a tropical state. The waters are about the size of Texas.
"Our main concern at the present time is to make sure that those thousands of residents who are going to have their house inundated with the rising water levels … are safe, secure and well-fed."
Julia Gillard, the Australian prime minister, who toured inundated regions on Friday, said the floods had been devastating and would clearly have an economic impact.
"We're still directly battling floodwaters - we haven't seen the peak of the flood yet at centres like Rockhampton - so the people of Queensland in many places are doing it tough today," she said.
Gillard said the mining sector had been particularly badly hit, with some companies using the force majeure clauses in their contracts.
"They've had to say to the people who buy their minerals that at this time, circumstances are such that they can't keep supply moving," she said.
"Even those mines that could continue to mine obviously have got difficulties with supply routes because so many roads have been affected.
Gillard said farmers, small businesses and tourism would also suffer.