Friday, 19 May 2017

Clarence Valley NSW: a timely reminder as widespread rain again hits the Australian east coast

Australian Bureau of Meteorology probability forecast for 19 May 2017 as of 18 May here.

The Daily Examiner, 8 May 2017, p.3:
THE flood protection around Grafton is not as robust as many people believe warns a local emergency management specialist.
The Clarence Valley Council’s emergency management officer Kieran McAndrew said up-to-date modelling showed Grafton levees capable of withstanding a one in 25-year flood.
“Many people are under a misunderstanding the levees provide one in 100-year protection,” he said.
“They don’t. They were designed to provide that level of protection, but better modelling in the 50 years since they were constructed shows they only ever provided on one in 25-year protection…..
Mr McAndrew said recent major flooding in the Tweed and Richmond and moderate flooding in the Clarence had revealed the lack of understanding of flood protection in and around Grafton. He said there was a danger of complacency in the community……
“If there was a prolonged overtopping event in Grafton it would be much more serious than Lismore because in Lismore there are hills people can reach from the CBD. We don’t have that luxury in Grafton. And because of the volume of water in the Clarence, flood heights fall much more slowly. It means the city would be inundated for much longer.”
He said the Clarence Valley Council had applied to the NSW Government for a grant for a project to determine the floor heights of all properties in flood-prone areas around Grafton. The data would help residents understand the potential impact of a levee overtopping on their property.

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