Reducing water levels in the Wivenhoe Dam could have lowered flood damage during the Brisbane flood crisis, but a lack of adequate information hampered releases, according to two new reports.

The hydraulic modelling reports by Sinclair Knight Merz (SKM) and WMAwater suggest there may have been some benefit from reducing dam supply levels.

The reports were commissioned by the Queensland Floods Commission of Inquiry, and are now open for public comment until September 1.

The SKM report says a large number of gauges are located within the Brisbane River catchment below the dam, but most don’t have reliable rating tables.

“There was little reliable information available to calibrate modelled flows from the hydrologic models downstream of Wivenhoe Dam,” SKM says. “This was exacerbated by a number of stations that failed during the event.”

The WMAwater report by engineer Mark Babister says flood reductions would have been a benefit but there was not enough data available at the time to make such a decision.

“Earlier releases from Wivenhoe Dam during January 9-10 could have reduced the eventual peak outflow and the resulting severity of flooding experienced downstream,” Mr Babister says.

“However, with the information available during their operations, and using strategies defined by the manuals we believe the flood engineers achieved close to the best possible mitigation results for the January 2011 flood event.”