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Image 1 for From the Tawny Frogmouth: Seawall puts our beach in peril

Beach breaks rely on sand. And sand is in short supply from Collaroy to Narrabeen. For decades, leading coastal experts have called for voluntary property buyback along Collaroy.

Image 2 for From the Tawny Frogmouth: Seawall puts our beach in peril

The Seth swell arrives. “Don’t come up here, this is private property.”

Image 3 for From the Tawny Frogmouth: Seawall puts our beach in peril

Seth aftermath.

Image 4 for From the Tawny Frogmouth: Seawall puts our beach in peril

Forming a line in the sand at Collaroy, locals protest against the seawall. When it was under construction.

From the Tawny Frogmouth: Seawall puts our beach in peril

11 January 22


The Collaroy-Narrabeen embayment is one of the most beautiful parts of Sydney, and arguably Australia’s surfing capital.

It boasts an unrivalled history in developing world champions, creating world-leading innovations, serving as a competitive breeding ground for current and future surf champions, while also playing host to the best of the best in this year’s WSL event. The prospect of doing anything to put this golden stretch of sand at risk is horrifying. 

Not only is it world renowned for surfing, it’s also well known in coastal science circles, being one of the most studied stretches of coast in the world. My dad, Professor Andy Short, started surfing here in the 60’s, hitch hiking from Lane Cove just to get the thrill of riding a wave. He would leave his board at Doc Spence’s house, forging his address so he could surf in the North Narrabeen contests (locals only allowed). This place inspired him to spend a lifetime studying beaches and measuring rips.

Recently, Surfrider Foundation published its yearly list of the 10 most at risk waves in Australia. North Narrabeen National Surfing Reserve (a protected place as gazetted by the government) occupies number two position, with number one going to South Narrabeen. How and why, in 2021, can a beach be at risk, especially when we know so much about them and how the coastal processes work?

As a prominent local coastal engineer stated, “Vertical seawalls are a 19th century response to a 21st century problem”. Constructed to protect historic beachfront subdivisions, Collaroy’s 7 metre vertical wall is a monster from which the public asset (the beach) and its ability to generate quality waves may never recover. 

It will ensure backwash, further degradation, and ultimately destroy the beach. Vertical seawalls, particularly on narrow beaches, “ringbark” the beach, directly reflecting wave energy when exposed, increasing erosion, strangling the beach’s ability to repair itself. The planned extension of the vertical wall must be stopped. 

Since Surfriders’ Line in the Sand protest at Collaroy on 27 November, it’s clear the beach is already disappearing. The water table, with nowhere to go, has turned the sand to liquid like quicksand. People walking in front of the wall are sinking up to their knees. The beach is slowly floating out to sea, soon to be gone.

What was predicted to occur once the vertical seawall was built has happened within weeks, thanks to a single big swell coinciding with a week of 
king tides.

Beach breaks rely on sand. And sand is in short supply from Collaroy to Narrabeen. For decades, leading coastal experts have called for voluntary property buyback along Collaroy, combined with regular massive beach nourishment for this beleaguered stretch of sand. Coastal experts also recommend sloping rock revetments, which are much better suited and have already been successfully built to the south towards Collaroy. 

The line in the sand has drawn community attention to what’s happening at Collaroy. Rather than the proposed extension of the vertical wall, strategic, long-term, viable alternatives are required. Beach users and community groups need to be properly engaged and consulted for any designs going forward.

 - AUTHOR:  BEN SHORT - *Ben is the Chair of North Narrabeen National Surfing Reserve

ORIGINAL TAWNY FROGMOUTH ARTICLE HERE



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