Outdated modelling was behind the slow escalation of flood warnings along Melbourne’s Maribyrnong River before hundreds of homes were inundated, a parliamentary inquiry into last year’s Victoria floods has been told.
Victorian State Emergency Service chief officer of operations Tim Wiebusch explained on Thursday October 12 how authorities were caught off guard by the severity of flooding along the river in October 2022.
Warnings for moderate flooding were sent out from October 12 before door-knocking of about 115 at-risk homes began, based on the scenarios provided by the Bureau of Meteorology and Melbourne Water.
“What then ensued on that Thursday night and into the early hours of Friday obviously was quite a significant rainfall event, with just on 100mm to 130mm across the catchment,” Mr Wiebusch told the inquiry.
Warnings were escalated on Friday morning as the projected river peak was revised to 3.2m, prompting police and SES to doorknock another 200 homes from about 3am.
Phone alerts were also issued as the forecast river peak continued to grow.
The Maribyrnong River eventually peaked at 4.216m.
Mr Wiebusch, who led the state’s response to the devastating floods, said the warnings were based on the best modelling and forecasting at the time.
“Because of the flows that were seen through the Keilor gauge, they’ve (Melbourne Water) now updated their rating tables,” he said.
“And so we may have seen a different set of arrangements with warnings if you were to replay that event now, based on the fact that there’s more intelligence to inform future modelling.”
Mr Wiebusch pushed back on suggestions the SES should be stripped of its lead agency role for future floods.
“If you look at the history of what we’ve been able to do since the 2010/11 floods … and then what our people were able to affect during the (2022) floods – responding to over 20,000 requests for assistance, undertaking 15,000 flood rescues and working with such a wide section of our emergency services – … we’ve demonstrated we can bring that together when it’s needed,” he said.
