But not everyone is happy with the project. Earlier this year,residentslined the beach in a bid to encourage the council to invest in alternative measures to protect the beach,including a nourishment plan that would artificially replace the sand. The local community group has been protesting against a seawall for almost 30 years.
Senior lecturer at the University of NSW Water Research Laboratory Mitchell Harley said annual king tides had combined with ex-tropical cyclone Seth to create north-easterly waves that had resulted in coastal erosion along Collaroy and other beaches along the east coast.
“Collaroy normally gets waves from the south and has a big headland that protects the beach from waves,but the combination of large tides and unusually north-east waves make beaches that would normally be protected,exposed,” he said.
He said more research would be needed to determine the extent the seawall played in Tuesday’s erosion event,but that north-easterly waves were certainly a key driver in drawing sand off the beach.
University of Sydney coastal geomorphologist Professor Andrew Short said coastal erosion events were likely to become more frequent as climate change increased the likelihood of tropical cyclones and east coast lows.
“They are predicted to be more likely and more intense. It’s a double whammy,” he said.
“Most communities are built on the southern end of beaches but they will be more exposed to the impacts of erosion because of easterly storms. Governments and coastal managers need to be aware and plan for those coming changes.”
President of the northern beaches branch of the Surfrider Foundation,Brendan Donohoe,said Tuesday’s conditions had been treacherous to beachgoers,leaving Collaroy Beach a “hellscape”.
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“It was a public beach,now it’s a public hazard,” he said. “If we get another big swell over the next few weeks,unless the council mechanically moves sand in,this beach will be impassable.”
He added that,while Tuesday’s conditions had been moderate,there were real concerns about how the coastline would fare during larger erosion events.
Mr Donohoe and other concerned residents will attend a council development application meeting opposing plans to build the next section of the seawall in the coming months.
A Northern Beaches Council spokesperson said the recent weather had caused minor erosion at Collaroy and Narrabeen,along with other locations in the area.
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“This level of erosion is not uncommon during large swell and tide events of this nature and is not a direct result of the seawall under construction. The beach will recover once conditions ease,” the spokesperson said.
“The rocks exposed from the recent high tides and large swell are part of the temporary rock bund that is protecting the seawall being built during construction which will ultimately be removed once construction is complete.
“The bund extends approximately 10 metres seaward and has been inspected and is intact. No other construction material has been observed washing into the sea. The area will continue to be monitored for safety and access.”
The beach was closed on Wednesday due to powerful surf conditions.
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