THE hydrologist who oversaw the design and construction of the Wivenhoe dam has defended its operator from criticism that it caused the Brisbane floods last month.
Neal Ashkanasy made the comments yesterday as SEQWater, which manages the dam, began releasing 25 per cent of the water in Wivenhoe to increase its ability to absorb further heavy rainfalls.
Some engineers have suggested that draining water from the reservoir in early January would have reduced the flooding in Brisbane, but Professor Ashkanasy said such "extraordinary claims" could only be made in hindsight.
Advertisement: Story continues below Professor Ashkanasy, a former national president of the Hydrology and Water Resources Institution of Engineers and now a professor of psychology at Queensland University, believes criticism of the dam's operator stems from a desire to blame uncontrollable events on human intervention and to seek "certainty over uncertainty."
He told the Herald: "To say those in charge of Wivenhoe 'caused the flood' provides a good headline, but it's nonsense. The flood was caused by heavy rain in the Brisbane River catchment area, not because of the way the dam was operated.
"Yes, there are calculations that suggest releasing more water would have lessened the flood, but all of these figures are worked out with the benefit of perfect hindsight."
He believed SEQWater operated the dam's spillway gates "responsibly" and in accordance with long-standing guidelines and that, without the flood mitigating effect of Wivenhoe, last month's flood might have been 1.5 metres higher.
Had SEQWater not begun releasing water from Wivenhoe on January 11, Professor Ashkanasy said, there was a possibility a fuse plug in the dam - designed to automatically collapse and release a large volume of water to quickly lower the level of the reservoir - could have been triggered.
If that had happened, you would have a very serious situation, with the height of the flood and, more importantly, the speed of the flood greatly increased.
"People would have had to flee for their lives as the water would have risen very, very quickly. My understanding is the level of water was only 60 centimetres from the fuse plug and that the dam was rising at about 10 centimetres an hour."
The management of Wivenhoe, built after the 1974 floods, will be a central issue in the inquiry set up by the Queensland Premier, Anna Bligh. But just over half of Brisbane's run-off water comes from the Bremer River and Lockyer Creek, which run into the Brisbane River below the dam.
http://www.brisbanetimes.com.au/env...am-operator-says-designer-20110220-1b13o.html