Beachside homes under threat as storms smash coastline

Massive storm waves combined with high tides have eroded parts of Sydney’s northern beaches by “up to 25 metres”, placing multi-million dollar waterfront homes at risk.

Storms that lashed most of the state over the weekend brought waves of up to six metres to the Collaroy-Narrabeen area on the weekend as residents braced for the impact of high tide on Monday morning.

“Basically, the next few hours will be critical," Mitchell Harley, a coastal researcher with the University of NSW, told SMH ahead of the 10am high tide.

Pictures from the Collaroy beachfront show thick sea foam and powerful waves coming within metres of houses along the beachfront on Monday morning.

Mr Harley warned erosion in the area could worsen next weekend if a tropical cyclone in the Tasman Sea veers toward the NSW coast as predicted.

'Plenty of sea foam going into backyards, but erosion risk dropping. Impact to houses spared, ready to go again for next weekend's forecast massive waves and already eroded beaches,' Dr Harley wrote on Twitter at about 10am.

The scene was reminiscent of the damage caused by an east coast low that struck the same area in 2016.

Several waterfront homes in Collaroy were destroyed and a swimming pool from one property slipped into the ocean.

A temporary sea wall installed after the storm could now be exposed, Dr Harley told SMH.

The damage could take months to recover from, with beaches recovering a metre of eroded sand every 10 days, according to the publication.

Nearby multi-million dollar waterfront homes at Narrabeen Lagoon were underwater on Sunday and residents evacuated. Schools were closed on Monday, but by late Monday morning most Narrabeen residents were permitted to return to their homes.

Communities along the Hawkesbury River, north of Sydney, and the southwest Sydney suburbs of Moorebank, Chipping Norton and Milperra were also ordered to evacuate.

The SES said people risked being trapped without power and water if they didn't leave these areas.

Emergency services have been swamped with calls since the deluge set in on Friday, while the extreme weather has caused transport chaos across Sydney.

"This wet and windy weather is really wreaking havoc on our roads today, with paramedics responding to five car accidents every hour since Friday night," NSW Ambulance spokesman Giles Buchanan said on Sunday afternoon.

"We've responded to multiple trees that had fallen onto cars, trees into houses and units, and people trapped in cars in floodwaters."

NSW Maritime says a number of boats have been sunk by the turbulent conditions at sea.

And the deluge is not over yet. Flooding is expected along the entire NSW coast and damaging winds and heavy rain are set to batter the NSW south coast on Monday.

Sydney, the Central Coast and the Blue Mountains were soaked after receiving between 200mm and 400mm of rain from 9am Friday to 5pm Sunday.

The last time Sydney and the state's coast had as much rainfall was in mid-2016.

with AAP

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