THE head of the Queensland floods inquiry has described a crucial part of the operations manual for Brisbane's Wivenhoe Dam as a mess.
It comes a day after a lawyer representing Ipswich City Council grilled the Bureau of Meteorology's Queensland chief on warnings issued ahead of January's floods.
The Queensland Floods Commission of Inquiry yesterday heard from a third engineer, Terry Malone, who directed releases from the dam in January's floods.
Engineers have told the inquiry how they used models that didn't factor in forecast rain when moving to operating phase W4, which allowed them to make large releases from the dam in order to save it from collapse, even if that meant flooding properties.
More than 14,000 Brisbane homes were flooded on January 13, the day after more than 3000 homes were flooded in Ipswich.
Yesterday, Mr Malone was questioned over the manual and how engineers took into account models with and without forecast rain, as well as the height of the Wivenhoe Dam lake when making their decisions.
Commissioner Justice Catherine Holmes said that part of the manual was a mess.
"This really is a bit of a mess, isn't it?" she said.
Mr Malone replied: "It's a very difficult concept, yeah."
Justice Holmes disagreed, saying, "It's not the concept, there are three different ways in which it's expressed in the manual."
On Thursday, Peter Flanagan, for Ipswich City Council, asked BoM regional chief Jim Davidson why the BoM's flood warnings for the Bremer River changed dramatically during January 11.
"In the course of seven-and-a-half hours the prediction from the bureau in fact increased from 12.7 metres through to 22 metres," he said.
Mr Davidson referred questions about modelling to his chief hydrologist, saying he took part in teleconferences about the floods but he didn't communicate directly with the dam engineers.
"I was certainly aware of the significance of the releases that were being discussed at the time," he said.
The Bremer River peaked at 19.4 metres on January 12, lower than the 22 metre warning of January 11.
More Ipswich News: www.QT.com.au