A sand dune collapsed on a man as he was digging into it at Muriwai Beach. Photo: Supplied/Auckland Rescue Helicopter Trust
More education on the dangers of sand dunes is needed, says an expert, after a man was left in a critical condition when a dune collapsed on him at the weekend.
The Auckland Rescue Helicopter Trust said the man was digging a hole in a sand dune when it collapsed on him at Muriwai beach on Saturday evening.
The helicopter rescue crew were called to the beach on Auckland's West Coast shortly after 5pm to help a male in his twenties who was buried head first in the sand dune.
He was flown to Auckland City Hospital in a critical condition.
In 2023, a boy was killed after he and a friend were trapped in a collapsed dune on Aotea Great Barrier Island.
The boys, aged 12 and 14, were flown to Starship Hospital, both in critical conditions, after becoming trapped as they dug tunnels in dunes during a family picnic at Medlands Beach.
Levi Sonchai Golaboski, 12, was taken off life support days later.
University of Auckland senior lecturer in civil engineering hydraulics Dr Colin Whittaker wanted to see more public education about the dangers of sand dunes.
"As we come into summer, there will hopefully be public awareness campaigns about the risks of drowning to try to save more lives and keep people safe on the beach or in the river. I'd like some messaging about sand dunes - or just sand in general - not being particularly stable, tacked onto the back of that.
"It may not affect as many people, but if anyone can avoid that happening to them so much better."
It was crucial to realise that just because the sand was still, that did not mean it was stable, Whittaker said.
There were multiple reasons dunes could become unstable, including getting cut by waves, vehicles driving over them, people walking on them or digging into them.
That instability could lead to them collapsing without warning, he said.
"If you've got a big dune above you and a lot of that collapses, you've potentially got something that weighs as much as an elephant collapsing on top of you - that's obviously very damaging, but also pretty hard to dig yourself out of especially if you're struggling for air."
Rescuing someone trapped in sand could be extremely difficult.
"As soon as you start trying to dig someone out, as you dig a hole, the sand fills it back in. It's incredibly challenging to do."
Sand weighed more than two and a half times as much as water, Whittaker said.
It was not just burrowing into dunes that could lead to potentially fatal outcomes - digging holes on the beach big enough to stand in ran the same risk.
"If you dig a deep enough hole and you've got near vertical side walls and you're inside that hole, the whole thing can collapse on you. Is it more or less dangerous than a dune? You're probably in equal amounts of trouble if all of that falls on you."
He advised being aware of one's surroundings and the potential risks.
"If you're looking at water, you want to think how deep is it, how fast is the current moving? For a dune, or if you're in a hole you're digging, it's probably how much sand is above me? And if it fell, how much could potentially fall on me?"
Even small changes in sea level rise caused by climate change could exacerbate the issue, with larger waves scoring out more of the dune than they might otherwise, and smaller waves that previously may not have reached the toe of the dunes now contributing to the erosion.
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