The head of Queensland’s reconstruction taskforce, Major General Mick Slater, has today rejected claims that operators of the Wivenhoe Dam were responsible for the floods in Brisbane. And leading water experts have told Crikey, ahead of an inquiry into the January floods, that allegations that the inundation of the Brisbane River was preventable are simply untrue.
Professor Neal Ashkanasy, a former hydrologist who oversaw the planning and building of the Wivenhoe Dam after the Brisbane and Ipswich floods of January 1974, says claims that the flooding of the Brisbane River was avoidable — pushed by The Australian in recent weeks — is “total nonsense”.
“We didn’t know the flood was going to occur a few months ago,” he told Crikey. “My concern is with people who keep talking about what they should have done before we even knew the floods were going to occur — it is all based on what could have been.”
The professor, a water resources engineer and psychologist who works at the University of Queensland, says the Wivenhoe Dam in fact limited flooding and those who said otherwise are from “some other planet”. Without the dam, flood levels would have been 1.5 metres higher in Brisbane and even up to four metres higher in other regions.
In fact, Professor Ashkanasy says the government could not have released water from the dam even if it wanted to: “During the flood itself, you can’t take those sorts of risks — you risk the integrity of the dam itself.”
Associate Professor Stewart Franks, from the University of Newcastle, agrees. He told Crikey: “Even if they had let out five or ten per cent [of water], it would not have made much of a difference.”
The Queensland government recently announced 25% of the dam’s water will be released over nine days from later this week until the end of March. The management of the dam during last month’s floods is currently being assessed by a Commission of Inquiry.
Former Deputy Director General of the NSW State Emergency Service and flood management researcher and consultant Chas Keys has called for calm — wait for the results of the inquiry, he says, before drawing any immediate conclusions.
“The Wivenhoe Dam probably helped mitigate the flooding by storing some of the floodwaters for a time, thus giving people more time to react before the flooding occurred in Brisbane,” he said. “Had there been no dam, there would have been no possibility of delaying the flood flows.”
Some experts argue that the dam held too much water in its flood compartment on the weekend of January 8-9 and believe the subsequent release of a large amount of water on January 11 produced most of the flooding. Hydrometeorologist Aron Gingis says the decision to reduce water levels in the Wivenhoe Dam should have occurred last year.
“I am the one who warned the government and associations about the issue and they just brushed me off,” he told Crikey. “I was aware this problem could occur almost two years before it happened. I strongly believe they [the Queensland government] have mismanaged the dam.”
Gingis believes the dam should have been reduced by 30%-40% and says the government was “greedy” to keep the dam levels high.
But economist and engineer Professor Trevor Grigg, from the University of Queensland, rejects this view: “I don’t accept that the flooding that occurred in January in both Ipswich and the Brisbane River would have been avoided if the dam was handled in some different fashion.”
Professor Grigg, who after the floods of 1974 wrote a report for the-then state government on the flood mitigation advantages of Wivenhoe Dam, said the issue “requires far more explanation that is being provided”.
“I think unfortunately what they are doing is re-inforcing the view that ‘if only we get the operation of the dam right, we won’t have any flooding of this river’ — that is a very dangerous view.”
Keys says he would be surprised if the inquiry — headed by Commissioner Justice Catherine Holmes — concluded anything controversial, but says it should address what he calls a legitimate question: “To what extent should dam engineers act on bureau forecasts? People are going to act on forecasts when they are wrong — they are educated, scientific guesses of the future.
James Ball, Associate Professor from the School of Civil and Environmental Engineering at the University of Technology Sydney, says the issue is subject to various inquiries and an assessment could not yet be made.
“There are too many unknowns in the information available at the moment,” he told Crikey.