Residents of the central Queensland city of Rockhampton have been warned they could be isolated for up to 10 days as the Fitzroy River builds towards its expected flood peak.
Large parts of the city were filling with water on Saturday and the Fitzroy is predicted to peak at 9.4 metres by Wednesday.
The town's airport is closed to all but emergency flights from Saturday afternoon reports the ABC.
Mayor Brad Carter says residents are likely to be cut off for 10 days once the Bruce Highway to the south and the Capricorn Highway to the west are closed by floodwaters, possibly some time on Sunday.
The river was up about 8.5 metres on Saturday morning and between 2000 and 4000 homes are expected to be inundated over the next few days.
Compulsory evacuations have been ordered and residents are moving into an evacuation centre at Central Queensland University.
Retailers are racing against the clock to get food supplies in before the southerly road link is cut.
Four Army Blackhawk helicopters and a Chinook are on stand-by to make food drops to isolated rural properties.
Authorities are preparing to airlift bulk cleaning equipment to the central Queensland town of Emerald, which has seen off its biggest flood on record.
The Nogoa River peaked on Friday, submerging 80% of the town.
More than 1000 homes have water over the floor boards, while 95% of commercial properties have flood damage.
The water started to subside on Saturday but 1300 people remained in evacuation shelters, where they celebrated New Year's Eve.
The clean-up is also expected to begin at Bundaberg, where about 300 homes and 120 businesses were inundated in recent days.
The Burnett River peaked at 7.9 metres on Thursday.
Western Downs Regional Mayor Ray Brown says floodwaters at Condamine are still hovering around record heights and it could be a week before residents can return to the town which has been evacuated.
Elsewhere, the town of Theodore has been inundated by floodwaters again, at higher levels than last weekend.
The town's 300 residents were evacuated and have been living at a mine camp in Moura.
Flood of 'biblical proportions'
Queensland's treasurer Andrew Fraser says the state is suffering a disaster "of biblical proportions" that will set back its economic recovery.
The treasurer has been forced to delay delivering his mid-year Fiscal and Economic review so he can factor in enormous costs from the floods.
He's warned of huge clean-up, recovery and assistance costs, and reduced royalties as the mining industry recovers.