Popular Adelaide beaches will soon begin receiving truckloads of sand to help overcome erosion and sand drift, amid concerns that the condition of some shorelines is currently the "worst it has been".
From March, thousands of tonnes of sand will be used to help rebuild the shoreline, starting with 10,000 cubic metres collected from the Semaphore breakwater to bolster the local dunes.
Trucks will then begin carting 15,000 cubic metres of quarry sand to Henley Beach and Henley Beach South, with another 50,000 cubic metres to be poured into West Beach to maintain dunes there.
"Last winter we didn't have any major storms, but we had a number of minor ones that had a similar impact to a major storm when you put them all together, and that lowered beach levels significantly," Environment Department coastal manager Murray Townsend told ABC Radio Adelaide's Stacey Lee and Nikolai Beilharz.
"West Beach is the beginning of that cell, the southern end of that beach cell, where all the sand moves from, so if we put sand into that area it eventually moves along the beach and maintains the beaches all the way north."
Given the price of sand — "in the order of $65 to $70 a cubic metre" — the total cost of the operation could be around $4 million, Mr Townsend said.
State MP Matt Cowdrey, whose beachside seat of Colton stretches from West Beach to Grange, said Henley Beach and Henley Beach South were currently in "by far the worst" condition that he could remember.
"Residents who have been in the area for many, many years on the shore front have said that this is the worst it has been ever," he said.
Sand-carting has been a common feature of Adelaide's coast over the years and decades, but has not been without controversy, and has created a north-south divide of sorts.
Residents have repeatedly expressed concerns about heavy trucks on beaches, while some at Semaphore Park have strongly objected to sand being taken from their beaches and moved further south, leaving the more northerly dunes also at risk of erosion.
"I don't think the ecosystem there could stand having any more taken out of it. The sand hills themselves, I feel, were in danger of practically disappearing," Semaphore Park retiree Brad McAlpine said.
"It was all taken from the local beaches here in Semaphore and Largs and transported … to West Beach and just put on the rocks there."
But Mr McAlpine said he was reassured to hear that sand would be taken from the local breakwater, rather than the beach.
"There is quite a lot of sand that could be dredged from the ocean in that bay itself," he said.
"This proposal that they've got to take quarry sand and replenish West Beach, that's good. That's not affecting the erosion issues we have.
"I would suggest there needs to be a good solid look at what is causing that erosion from West Beach and so forth, washing towards Semaphore."
Largs resident Jill Kennare said reducing reliance on beach sand was good for the environment and would reduce the number of trucks and bulldozers on the northern beaches.
"In the short term, as a resident of this area, I'm reasonably happy with what they've come up with; I think it's a win-win solution for the north and the south," she said.
But she was concerned that the current plan included removing sea grass that had built up on the beach at the Semaphore breakwater.
"It's a food source for a lot of the birds but also the crustaceans and other organisms within the sand … so you're removing a major food source from the ecosystem," she said.
"With sea level rise, I think we need to plan for adaptation strategies. It's not in the too-distant future where we're not going to be able to hold the seawater back, like a King Canute, with that sea coming in. We've got to adapt."
The state government is currently conducting a review into that very question, examining alternative options to help manage Adelaide's disappearing beaches.
'Mass fill' needed, local council says
Charles Sturt Council chief executive Paul Sutton said his council, which includes West Beach, Henley and Grange beaches, was "immensely grateful" to receive sand.
But he said the amount was only a "small contribution … in the greater scheme of things".
"These are tiny little drops in the bucket that is the problem along these areas of the coastline," he said.
"We have a problem where around about 115,000 cubic metres per year moves northward along the coast from these areas.
"Putting 10,000 and 15,000 into these two spots where it's practically eroded at the moment is really a small percentage of what annually moves out of these areas."
Mr Sutton believes a "mass fill" is needed to re-establish a "healthy beach profile".
While Mr Townsend said there was only a finite amount of sand in Adelaide's beach system, the use of quarry sand over the past two years has reduced pressure on the coast.
"We're getting 65,000 cubic metres from outside the beach system this autumn … [and] the quarry source was decided to be most appropriate in this instance," Mr Townsend said.
"We can specify the quality, as in the grain size and the mix of sand, that we purchase from the quarries and so we compare that with the native sand.
"It is more expensive than getting sand from within the beach system, but the idea of bringing sand into the beach system from outside also helps us deal with things like rising sea levels in the future as well."
