The beloved beach was washed offshore by Cyclone Alfred, but most of this sand returns

For many, the most visible impact of Cyclone Alfred was the damage caused by the large waves and storm surges on their local beaches.

Beaches in southeast Queensland and northeastern New South Wales are being hurt by dramatic sand cliffs that include tourist draw cards from Surfers Paradise.

Sand islands off Brisbane in Bribby, Morton and North Stradbroke protected the city from the worst storm surges. But they made it happen, reducing their ability to protect the coastline.

The good news is that the sand has never disappeared. Most of them now sit in a sandbar offshore. Over time, many beaches will naturally replenish. However, the dunes take time. And there are areas where damage remains.

Why did you do so much damage?

Cyclone Alfred went up and down the coast for two weeks before crossing the mainland as a low tropical one. On February 27th, we reached Category 4 off Mackay. From here, the intense cyclone winds launched a very large swell.

By the time the cyclones were heading towards the coast, many beaches were already struck by waves that caused erosion. This meant they were more vulnerable to storm surges and further erosion.

It coincided with one of the best tides of the year when Alfred moved west to land. As a result, many beaches have been stripped of sand and coastal infrastructure weakening in some places.

Which beach was hit the hardest?

The region south of the Cyclone Truck was hit hardest from the Gold Coast to the Kitagawa River.

Some beaches and sand dunes have been heavily eroded. Peregian Beach, south of Noosa, lost up to 30 meters wide.

Erosion cliffs, or “cliffs,” appear to be up to 3 meters tall on the Gold Coast. It exposed the final boundary section of a buried coastal defense known as the A-line, built following a massive storm in the 1970s.

Most dunes above and below the Gold Coast, just behind the beach (formerly edunes) are eroding, affected by a surge up to 0.5 meters above the tide mark. Furthermore, even established sand dunes are eroded.

Where did the sand go?

In just a week, millions of tons of sand on our beach seem to have disappeared. Where did you go?

The beaches are constantly changing and extremely resilient. These terrains always interact with waves and currents, so they adapt by changing shapes.

With more energy in the waves and currents, the beach becomes flat and narrow. The sand is pulled away from the beaches and dunes and washed off the coast, where a sandbar forms. These sandbars actually protect the rest of the beach. It will allow the waves to break even further offshore.

Dunes are when sand is blown off the beach on very windy days and then dunes form when they land further inland. Over time, plants calm the dunes. Their roots act to stabilize the sand.

Healthy sand dunes covered with vegetation are usually difficult to erode. However, as the beach is washed away during a big storm and the water levels rise, larger waves could directly attack the dunes.

The dunes dined, creating tall erosion cliffs. In some areas, seawater is flooded inland and can damage dune plants.

Most of the sand is back

Once coastal conditions return to normal, much of this sand will naturally be returned to land. Our beaches are again steep and wide.

It’s not immediately. This can take several months for it to happen and is not guaranteed. It depends on the conditions of the wave.

Some sand is washed in very deep water or flowed and swept away from the beach. In these cases, the sand takes longer to return or does not return at all. The dunes recover more slowly than the beach. It may take years for them to recover.

On the east coast of Australia is one of the world’s longest coastal drift systems, where sand is transported north by currents, eventually joining K’Gari/Fraser Island.

Can humans help?

The sand naturally returns to most beaches. It is usually best to do this natural process.

However, if extreme erosion threatens buildings and roads, you may need beach nutrition. Here we will speed up the refill process, in addition to sand-eroded beaches.

Other options include the construction of vertical breakwaters and sloping walls. These expensive protection methods work very well to protect the roads and buildings behind them. However, these designed structures often accelerate the erosion of beaches and dunes.

We can help the dunes away as much as possible. Plants that colonize early dunes are very fragile and can be easily damaged. Temporary fencing can be used cheaply to trap sand and help with the recovery of the dunes. Dune revegetation is an efficient way to reduce future erosion.

How should I prepare for the next episode?

Uncertainty about the tracks, strength and landing locations at Cyclone Alfred has sustained many people, including at-risk communities and disaster responders. This uncertainty puts many scientists under great pressure. Decision makers want fast and clear information, but that’s simply not possible.

In Australia, almost 90% of people live within 50km of the coast. Over the next few decades, the world’s coastal population will grow rapidly. More people are at risk, from rising sea levels to more severe natural disasters.

As the climate crisis deepens, reconstruction in high-risk regions can cause worse, more expensive problems.

Communities must begin to seriously talk about managed retreats from several areas of the coast. This means that they have chosen not to be built in areas that are susceptible to erosion, and not to protect against ocean invasion in some locations, and have begun relocating their homes and infrastructure to safer heights.

Decision makers should also consider deploying nature-based solutions such as sand dunes, mangroves and oyster reefs to reduce the threat from the ocean.

Since Cyclone Zoe landed in the region in 1974, technology has been advancing rapidly. Track the weather system from satellites, get the latest weather and wave forecasts on your mobile phone, and use drones to see changes in beaches and dunes.

However, these technologies only work when using them. The Gold Coast has the world’s largest coastal imaging program. However, most other coastal areas do not provide long-term monitoring of sand dunes and beaches. Without it, we have no access to data essential to protecting the beaches and communities.

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