Dam releases based on ‘rain on the ground’
Seqwater — the corporation responsible for managing Wivenhoe Dam — is adamant there was little more that could have been done by the dam operators to provide more flood mitigation,
Seqwater’s external relations manager Mike Foster said the agency only made decisions around “rain on the ground” not weather forecasts.
“We absolutely work with the Bureau of Meteorology in relation to weather forecasts,” he said.
“The way we do that, and we do modeling on rainfall forecasts to tell us where an event may gobut when we make decisions we want to make decisions around as much certainty as we can.
“And we make decisions around rain on ground and how much inflow we are going to get into our systems, and we can model that and that can tell us where our dam levels are actually going to go.”
Mr Foster said the alternative was to make a decision around a particular weather bureau prediction and let water out.
But he said if that forecast was wrong then the dam releases could flood Brisbane unnecessarily.
Releases from the dam, which contains the equivalent of Two-and-a-half Sydney Harbors worth of water, can take between 16 to to 24 hours to reach Brisbane.
They are usually timed to take into account the tidal flows into the river that lift water levels and inflows from the Bremer River and the Lockyer Creek downstream.
Mr Foster also revealed the dam had been about a quarter full on Tuesday and by the weekend it had Risen to nearly three quarters full from the extreme weather.
He said releases were underway from Wivenhoe to ensure the flood compartment was empty in case of another downpour.
Reporting by Rory Callinan