Australia’s beaches may have a hard time recovering if a third weather event occurs in La Nina this year after many of the more famous sandy stretches have suffered consecutive weather events that ripped the sand away.
As more extreme and intense weather events occur, once protected areas of beaches become more exposed, threatening coastal communities, experts warn.
Dr Mitchell Harley, a senior lecturer at the University of NSW Water Research Laboratory, said Australia’s beaches are very dynamic and tend to fluctuate depending on the season. During storms, the beaches lose more sand, while in the warmer months the beaches usually grow.
“We have been measuring Collaroy and Narrabeen Beach for 46 years and, with these measurements, there have been fluctuations over a huge amount of space, up to 100 meters back and forth. The coast is breathing and exhaling, but when we look at the long-term records, they have generally been stable recently, “she said.
“During major storm events, such as the one we have seen in the past two years, what we see is that the waves strip the sandy beaches. It does not disappear, it only moves into deeper waters. The sand slowly returns to the beach during the calming conditions.
In the normal summer months, the waves move from the south or southeast. This typically means that the northern end of the beach narrows and the southern ends get larger.
But during the events of La Nina, they move slightly counterclockwise and are further east, which leads to a greater risk of more beach erosion, particularly during the summer, and also “beach rotation” – where the beach realigns itself to the prevailing wind direction.
As a general rule, it takes five to ten days for every meter of sand from the coast to return to the beach, Harley said, and recovery can sometimes take months if the beaches lose up to 40 meters of sand. But if there are consecutive storm events, like what happened in the past two years with La Nina, the beaches may have a hard time recovering and start threatening infrastructure.
“If we see more frequent events, we will see continued pressure on beach properties,” he said. “Everyone wants to live close to the coast and there is always pressure to build more and more properties along the coast, but it creates hereditary problems that future generations will have to face, particularly with regard to climate change and the tremendous threats they can cause to the coast” .
For example, wave size and sea level will increase as oceans continue to warm, which will cause more damage to beaches.
The coastline around Sydney is expected to experience between 20 centimeters and just over a meter of sea level rise over the next seven decades. This means that the coast of the state can be expected to change significantly as climate change intensifies.
Meanwhile, tropical cyclones are likely to damage once-protected areas of the coast as they move further down the NSW coast.
“We haven’t seen that kind of erosion in the past and that could create new erosion hotspots and so that’s a big concern,” Harley said.
Harley is part of a team of researchers involved in a citizen science project that monitors beaches to gain a deeper understanding of how coasts change over time.
Mark “Dippy” DePena, 67, has been surfing the shores of Cronulla Beach since high school and said the coast has changed dramatically over the past 55 years.
“The sea does not forgive. Honestly, it’s very powerful, “he said.” We’ve had a weird time, but this is the worst Cronulla has seen since 1974 and we’re really starting to worry, “he said.” They had to move the lifeguard tower – dismantle it. physically – because it was beginning to collapse ”.
DePena isn’t sure if his beloved Cronulla Beach can withstand much longer without mitigation action, but he’s determined to do whatever it takes to preserve the beach – or what’s left of it. Twelve years ago, he teamed up with fellow surfer and friend, Andrew Pitt, to develop the Bate Bay Sand Placement Committee with the intention of improving the dedicated surf reserve and safeguarding the coast.
“People want to live on the ocean, right? But these seas have actually stolen some of these courtyards ».
Without adequate mitigation and adaptation efforts by government, councils and the community, ANU associate professor at Fenner School for Environment and Society, Dr. Liz Hanna, said there would be impacts on people’s health. . This includes moving and losing connection with the community.
“People will have to pay for their own coastal protection – some can afford it and some can’t,” he said. “Adaptation is complicated, holding onto the sea is terribly difficult.”
He suggested that, among other efforts, planned withdrawals must be considered before people are forced to be displaced. “We don’t really know how long we have, but we all agree that twisting the thumbs isn’t the right answer,” she said.
The NSW government is working with local councils to plan and respond to erosion, including monitoring what new developments can move forward, ensuring environmental and community benefits remain, and providing funding for mitigation work.
The Department of the Environment and Heritage also provides seven long-term offshore wave buoys and several ocean level recorders to measure changes.
Over the next 50 years, the Insurance Council of Australia has estimated that governments will need to invest at least $ 30 billion in coastal protection and adaptation projects.
“As the frequency and intensity of these events increase, an increasing number of exhibited properties in Australia will become uninhabitable,” a council spokesperson said. “Insurance coverage is limited in these areas due to the high and rising risks, creating a protection gap.”
The council found in a report released last year that governments at all levels need to invest at least $ 30 billion in large-scale coastal protection and adaptation projects over the next 50 years. CSIRO’s ten-year megatrend report, released last week, found that 150 million people around the world live on land that may be vulnerable to future sea level rise by 2050.
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