expert-pours-water-over-flood-planIt’s not every month a renowned physicist turns up to a local council meeting. And if anyone is going to know whether the Land Subject to Inundation Overlay mapping data is inaccurate, it’s a scientist. Silverleaves ratepayer Dr Mark Harrigan says Bass Coast Shire Council may be “overcautious” in measurements it has chosen to include in the controversial planning scheme amendment. G042914

By Gav Ross

THE validity of the mapping data used for Bass Coast Shire Council’s controversial Land Subject to Inundation Overlay (LSIO) has been questioned by more than a few residents in recent months.

Chief among them is Mark Harrigan, a ratepayer from Silverleaves who also happens to hold a PhD in Atomic Physics.
Attending last week’s council meeting, the scientist pointed out that the council’s “overcautious” overlay, particularly relating to what is proposed for Cowes East and Silverleaves, is fundamentally flawed.
Drawing on evidence in the very detailed CSIRO study ‘The Effect of Climate Change on Extreme Sea Levels along Victoria’s Coast’, Dr Harrigan says the council’s planning department has simply taken maps modelled on data from Tooradin and Stony Point and applied it across Bass Coast “in blanket fashion”.
Why does that matter?
Well, for starters, Tooradin is at the top of Western Port with a shoreline facing south, while the section of Phillip Island most affected by the LSIO (otherwise known as Amendment C82) is the complete opposite.
“In Silverleaves, we face north and Rhyll Inlet faces east, so the same logic doesn’t apply,” Dr Harrigan said.
“Tooradin faces south, we face north – therefore the storm surge and wind wave run up won’t be the same.”
Dr Harrigan added that the “best available science” also advises that wind patterns impacting storm surge in Western Port involves westerly and south-westerly winds.
“Again, this means that the north facing coast of Phillip Island and the Rhyll Inlet will experience reduced storm surge and wave action due to its orientation in relation to the wind,” he said.
Dr Harrigan said he will make a further submission to Planning Panels Victoria.
“The (Planning) Act specifically states you have to take into account local conditions and topography, which Bass Coast Shire Council has not done,” he said.
As detailed in his query read out during Community Question Time at least week’s meeting, Dr Harrigan believes the presence of coastal dunes and vegetation along the Cowes/Silverleaves shoreline would dissipate wave action considerably during storm surges.
While the majority of the 140 submissions handed over to council objected to the amendment, a handful were in favour of the overlay, applauding the council for taking a proactive step in the face of climate change.
“We should absolutely be preparing for climate change, but it should be based against the best science, not numbers plucked out of the air,” Dr Harrigan added.
“Some don’t realise that should this overlay go through, it will affect everyone in the shire, not just those on the maps.
“If it goes through, land value and insurance (premiums) could be affected, meaning everyone else’s rates could go up.”

Off to the panel
Following lengthy debate at last week’s meeting, councillors are opting to seek expert advice from the Planning Panel.
The main point of contention raised was whether Bass Coast should be preparing for a 0.8m sea level rise by the year 2100 or a 0.2m rise for infill development areas by the much-closer 2040.
Cr Andrew Phillips said he believes the council will be in a better position to make a decision regarding the amendment in early 2015 once that question was answered.
“By doing this we will be seeking clarity from an independent planning panel,” he explained.
“A lot of the submissions said we are planning for an unreasonable sea level rise.
“I don’t think we quite know enough to make a decision.
“In essence, we’ll ask the panel what they think is the proper way to go.”
Cr Brad Drew supported his colleague’s push to seek clear direction from experts.
“This will enable us to make a more concise decision moving forward,” Cr Drew said.
“After reading through the submissions, 129 people had concerns, and as a councillor I need to listen to those concerns.
“I think we all understand there are environmental changes upon us, but we need to proceed carefully, strategically and mindful of everyone’s concerns.”
Cr Phil Wright said the matter had been “blown out of proportion”.
“People who buy properties close to the ocean have issues and they know it,” he said.
“In my view, it’s buyer beware.
“I think the importance of this is well and truly overrated.”
The Planning Panel is expected to commence hearings to consider submissions in October.

Coastal concerns

OF THE 140 submissions received by the council, 129 were objections.
Common issues covered in objections included:
– Concerns about the scientific background behind the mapping and integrity of the data
– Planning for a 0.8m sea level rise by 2100
– The overlay in residential development sites where the ground level has been elevated using fill
– Consideration of reservoir discharges
– The requirement of a costly Coastal Hazard Vulnerability Assessment for developments below 5m AHD
– Planning for 2100 when a building may not last 85 years
– Concerns about property values and insurance premiums
– Concern that flooding in Silverleaves is caused by inadequate drainage
– The amendment doesn’t take into account possible future dredging of Western Port, if the Port of Hastings project went ahead
– Criticism that the coastal inundation information was not released earlier.