Brisbane's flood and the lessons of 1974
- 11 January 2011
- From the section Asia-Pacific
On the last weekend of January in 1974, as Australians marked their national day, an already abnormally wet summer saw new, near-record rainfall that swept floodwater through the city of Brisbane.
Car parks were submerged, boats broke loose and jammed under bridges, and roads collapsed. Debris was strewn along the river courses.
When the devastation was collated, 14 people had lost their lives and the cost of the damage at the time was put at A$200m.
It was the city's worst flooding of the century.
The high water mark that almost drowned the city 37 years ago was recorded at 5.45m (17.9ft).
Queensland's current Premier Anna Bligh says the flood surge coming to Brisbane on Wednesday and Thursday may well be similar.
By late January in 1974, almost every river in Queensland was in flood.
A very slow moving monsoonal trough producing heavy rain had drifted further south than normal and then met the weakening cyclone Wanda over Brisbane.
The city, which at 911,000 had less than half the population it has now, saw 6,700 homes totally or partially flooded.
A report by Australia's Director of Meteorology said some houses were washed away in creek flooding while others suffered badly from subsidence and landslips.
Around Brisbane, rowing and motor boats ferried people to higher ground as other residents waded chest-high through roads. The Albion Park racecourse became a swimming pool.
Nearby Ipswich, on the Bremer River, had 1,800 premises affected. Its flood high of 20.6m in 1974 is also expected to be equalled in 2011.
The director of meteorology defended the bureau's forecasting at the time, although admitting to "problems of dissemination and interpretation of the warnings" and referring to an "intolerable strain imposed on the staff by the volume and complexity of the data".
The report also said there was "some reluctance by the community to accept the gravity of the situation".
In the aftermath, some residents returned home only to be flooded again days later.
Others found that their insurance did not give them full cover.
The director of meteorology concluded: "Some people have been permanently affected, both physically and mentally, by the shock of the flood and its aftermath."
One outcome of the floods was the construction of the Wivenhoe Dam to ease pressure.
It is a mark of the severity of the 2011 rainfall that the dam has been forced into controlled releases, which are adding to the water levels.
By Tuesday afternoon, the dam was at 190% capacity and releasing the equivalent of 6,000 swimming pools of water a second.
One water official said: "If we don't do it now there will be more chance of worse flooding later. We want to control the release. We don't want it spilling over the top of the dam.''
One key recommendation of the director of meteorology's report from 1974 is sure to be scrutinised again in the coming weeks to determine whether it has been properly heeded.
"The January 1974 flood has shown that such a flood warning service is of limited value unless the bureau's forecasts are properly interpreted by responsible authorities, and the public is subsequently advised of the expected level and extent of inundation in their own streets and houses."