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Coastal erosion to worsen over next decade as storms wash WA beaches away

By Rebecca Trigger, Wednesday June 6, 2018 - 09:32 EST

Western Australia could be hit with some of the worst flooding and coastal erosion it has ever seen in the next decade, as the tidal cycle combines with increased water levels caused by global warming.

Recent storm damage has pounded the Western Australian coast, with the beachside town of Lancelin losing its gazebo at one of the community's main beaches, and a holiday home sliding into the ocean at nearby Wedge Island.

Other parts of the state, including Fremantle's Port Beach and Geographe Bay .

On Port Beach, that are the site of a former fuel depot, which locals fear pose a hazard to swimmers, while part of the carpark has also collapsed.



But UWA professor and oceans expert Charitha Pattiaratchi said this kind of devastation is just the beginning.

"In the next eight years our water level is going to increase by about 25cm, which is much higher than the water level increase for the last 115 years," Professor Pattiaratchi said.

"The mean water level is changing due to what we call the nodal tide, which has an 18.6-year cycle, and at the moment we're at the lowest part of that cycle."

Professor Pattiaratchi said climate change made this situation worse.



"Climate change happens in a very slow process … every 20 years, you actually have an increase," he said.

"So every time we actually come into that 18.6-year cycle, the higher water levels would be higher than the previous."

He warned a storm surge combined with a strong La Nina effect could see parts of Perth go under.

"If you have a La Nina happening at the highest period in the eight years' time, on top of that you have a storm surge occurring at the highest water level, we would have severe flooding, severe erosion," he said.

"For example, places like the Elizabeth Quay railway station would be underwater."

According to Mr Pattiaratchi, this came within two hours of happening in 2011 during cyclone Bianca.

At that time the system weakened before it hit the city.

Reclaimed land areas such as Riverside Drive, the Kwinana Freeway and the South Perth foreshore would also be at risk, Mr Pattiaratchi said.

WA's seaside-dwelling lifestyle under threat



In the shire of Gingin, about an hour and a half north of Perth, some small coastal communities have already seen major coastal erosion.

The recent storms have eaten away at the iconic Grace Darling Park, forcing the shire to demolish a gazebo, with fears the volunteer rescue office is also at risk.

The Western Australian Planning Commission's , published last year, call for public infrastructure to be removed and private property abandoned when access is cut off.

A as part of this process found the cost of trying to save at risk coastal areas may be too high.

"While it is natural that local communities would prefer to protect and preserve the current features of the coastal zone, the reality is that unless some new and innovative protection methods are developed, the costs of maintaining current features will likely become prohibitively expensive at some point in the future, given current sea level rise projections," the report said.



Shire President Sam Collard said if the Government's policy of managed retreat were to be applied, state or federal governments would have to foot the bill.

He said the shire, with just 5,000 ratepayers, would not be able to recompense landowners who lost property to coastal damage.



The shire spent $75,000 trucking in sand to shore up the park at Lancelin. Two weeks later, it was gone, washed into the ocean.

Mr Collard said while this method of shoring up the public beach would likely come up for debate at Wednesday's council meeting, there may be other, more workable options such as the seawall built in the town of Seabird, to prevent further losses.

Seabird attracted $2 million in Royalties for Regions funding in 2015 after large swells washed away part of the road on the town's foreshore.



But Mr Collard said the threat of coastal erosion would not be enough to break off Western Australians' love affair with oceanside living.

"There's a little bit of a 'not in my lifetime' sort of attitude," he said.

"People are prepared to do that, take the risk, I don't think people will stop coming at all.

"They're still building houses here, they're still building hotels, taverns, they'll continue to come I'm sure of it."


- ABC

© ABC 2018

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