At least 100,000 homes and businesses could be powerless in Brisbane and Ipswich, west of Brisbane in eastern Australia from Wednesday morning and thousands of people face evacuation as the cities brace for Queensland's flood disaster to hit, authorities said on Tuesday.

Ten people are dead and 78 others are missing, with fears the death toll could rise dramatically in coming days, after torrents of water swept through communities west of Brisbane, including Toowoomba.

The Brisbane and Bremer rivers will rise to levels exceeding the devastating floods of January 1974.

Electricity was switched off for safety reasons in the Ipswich Central Business District (CBD) overnight, with power to be cut to low-lying parts of the Brisbane City Council identified on flood risk maps, including the CBD, from 8.30 a.m. local time.

Authorities say more than 100,000 residents in Brisbane and Ipswich could be plunged into darkness from Wednesday as waters inundate communities.

Police have asked residents to avoid travelling to the Brisbane CBD on Wednesday, with many businesses expected to be shut.

"Current flood predictions suggest a number of inner city suburbs may possibly be inundated tomorrow (Wednesday), and police advise against all non-essential travel," a Queensland Police spokesman said in a statement late Tuesday night.

"Flooding risks in Brisbane are predicted to significantly increase on Thursday, and police are strongly advising against all travel in or around flood affected areas."

Queensland Premier Anna Bligh has warned the state to prepare for yet more tragedy, saying there were "grave" fears for 15 people in addition to those already confirmed dead.

Late on Tuesday Queensland Emergency Services Minister Neil Roberts said Brisbane port would be closed "to all but emergency situations".