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When will my beach look normal again

Tristan Meyers, Saturday April 25, 2015 - 12:57 AEST

People in New South Wales are still recovering from the storm that lashed eastern regions of the state last week, but the question on everyone's lips is "where did my beach go"?

Beaches are dynamic places that frequently undergo erosion events, such as the storm that occurred last week. Erosion events are characterised by a sustained period of larger than usual wave height. Last week, an offshore wave buoy in Sydney recorded a wave that was 14 metres in height - that's about as large as a four storey building!

The energy of these waves scrapes the sand off the beach profile, and moves it further out to the sea. Generally, the sand collects at a certain point further offshore, a point called the "depth of closure".

During calm periods, the sand is reworked onshore from the depth of closure. The width of the beach (the length from the dunes to the water) will then widen. This process is known as accretion. After a storm event it can take several months, or even years for a beach to return to normal under natural processes.

But not to worry! Many beaches around New South Wales undergo sand nourishment. Sand is physically dumped on beaches in order to protect coastal properties from being swallowed by the sea. This practice is common in the northern beaches of Sydney and in Port Stephens.

Residents around Bondi and Coogee also noticed that the sand that was on the beach has begun to collect far behind the beach, reaching parks and streets during the storm. As the sand was transported with the gusty gales, the beach adjusted to the high energy of the wind by retreating further inland. Basically, these parks and streets became active sand dunes!

Although the time will vary between beaches (and is still an active area of scientific research), we should see beaches with nourishment plans return to normal within a few months.

- Weatherzone

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