Council to look at sea level rises

Gosford Council will examine three different sea level rise scenarios before adopting the Brisbane Water Foreshore Flood Study.

The council has adopted a recommendation of its floodplain risk management committee to undertake additional modelling as part of the flood study.

The study, prepared by consultants Cardno-Lawson Treloar, found that 100-year peak water levels would be 1.59m above sea level at Ettalong and Woy Woy.

The study had recognised a potential 300mm sea level rise over the next 100 years due to climate change.

However, the committee asked that scenarios of an additional 0.18m, 0.55m and 0.91m also be incorporated.

The council resolved to defer the adoption of the Brisbane Water Foreshore Flood Study "pending the outcome of upcoming sea level rise Council workshops and further modelling of sea level rise".

The committee was told that three submissions had been received after the public exhibition of the study.

"One of the submissions had raised concerns that the flood study had not properly addressed sea level rise", the committee was told.

In its submission, the Central Coast branch of the Australian Conservation Foundation had argued that the study had seriously underestimated sea-level rise and had ignored predictions of more frequent and intense coastal storms.

The committee was briefed by the council's water sensitive urban design engineer Mr Peter Sheath, who gave "a brief background on the scientific research and latest predicitons on sea level rise".

"The committee was informed that Gosford Council had made several requests of the Department of Environment and Climate Change for a recommended value on the prediction of sea level rise along the eastern seaboard," according to the committee's minutes.

"The department had not provided any definitive value to date.

"The recent Floodplain Management Authority's conference in Wollongong, attended by Gosford Council officers, had also raised the issue with the department without any resolution.

"The issue of rainfall intensity increase was also still uncertain and the latest recommendation from the department was to continue sensitivity analysis up to 30% for any studies until more information comes available.

"The CSIRO is currently investigating this issue and it hoped to have further information on this matter later this year.

"Peter Sheath also presented various scenarios for development based on predictions for sea level rise.

"This included effects on existing development, predicted damages, erosion potential, extent of tidal inundation and the effects of sea level rise on existing infrastructure."

Mr Sheath also advised of the release of the Department of Planning's high resolution terrain mapping for assessments of potential climate change impacts.

The committee was told that "it was expected that the report would provide some recommendations from the NSW Government about climate change adaptation, such that NSW coastal councils can plan towards a coordinated and consistent response in the future".

"The report provides statistics about the amount of low-lying land and infrastructure however does not provide direction in adaptation planning."

Responding to a question within the committee, the council's senior integrated planner Ms Annie Medlicott "advised that Council was not including any such reference as yet but would continue to relate zonings to cadastre boundaries".

Council agenda FM.004, FM.073, 27 May 2008