Police say a man has drowned while swimming near Cylinder Beach on North Stradbroke Island off Brisbane on Monday, despite an easing of surf conditions after days of big swells from ex-Tropical Cyclone Oma.

Key points: Critical care paramedics were unable to save a swimmer on North Stradbroke Island

Critical care paramedics were unable to save a swimmer on North Stradbroke Island Noosa Beach and many Gold Coast beaches have been seriously eroded by cyclonic swell

Noosa Beach and many Gold Coast beaches have been seriously eroded by cyclonic swell Gold Coast Mayor says the coastal damage could have been worse

The man, described as a foreign national, got into difficulty while in the surf.

Critical care paramedics worked on the man but he was pronounced dead on the beach.

As the heavy coastal pounding from cyclonic swell finally begins to recede, authorities in southern Queensland are left to deal with serious beach erosion from the border to north of Bundaberg.

Ex-Tropical Cyclone Oma has been downgraded to a tropical low and is now sitting safely in the Coral Sea.

However, for much of the past week, councils from central Queensland to the New South Wales north coast have remained on high alert as the system moved towards the coastline.

On the Sunshine Coast, Noosa Beach — particularly prone to erosion — has been all but washed away.

'We dodged a bullet'

Along the Gold Coast, the big waves that swallowed beaches on the high tide pounded sand dunes and left sand cliffs in their wake with all the beaches on the Gold Coast remaining closed.

However, Gold Coast Mayor Tom Tate said the erosion could have been far worse.

"I think we dodged a bullet on this one," he said.

"We've been fortunate with Oma and the preparation we've done in the past.

"We've got some scarping from Palm Beach, Burleigh, Surfers Paradise and Narrowneck."

Beach erosion at Main Beach on the northern Gold Coast on Monday, after days of pounding swell. ( ABC News: Tom Forbes )

Dr Darrell Strauss from Griffith University's Centre for Coastal Management agreed many areas had escaped a more serious pounding.

"Look, we'll see the beach recover relatively quickly on the upper beach, but what we can't see is what's going on offshore," he said.

"There'll be a big storm bar out the back of the surf zone and once the waves stop breaking on that, it'll [sand] gradually move ashore.

"It'll probably take a few months to recover."

Authorities are urging people to stay away from sand cliffs which are at risk of collapsing.

Earth-moving equipment will be sent to the worst-affected beaches in coming says to reprofile the sand.

An earth mover preparing to tackle the heavy erosion on Noosa Beach on Monday. ( ABC News: Jacqui Street )

To better protect the southern Gold Coast, the council will begin building an artificial reef off Palm Beach the next month.

The reef will be constructed from large rocks and will measure 180 metres in length and 80 metres in width.

Councillor Tate said the reef would cost $18 million and take 18 months to construct.

"It'll be quite a large structure, but we need it to make sure this portion of our beach is safe," he said.

The artificial reef is expected to attract surfers and sea life, but fishing in the area will be banned.

Eroded dunes along Yaroomba Beach at Coolum on the Sunshine Coast. ( ABC News: Jacqui Street )

In Noosa, sand will be pumped to restore the famous beach along Hastings Street, and heavy equipment has been used to clear debris from the shoreline.

Carl Billingham from Noosa Shire Council said erosion had pushed sand further north up the coastline.

"We've got rock exposed at the moment and some of the sand has been taken out by the surf, but it's something we can easily fix in the next few weeks," he said.

"We've put some handrails along there so that people don't fall off the edge of the rocks.

"We did pump a lot of sand beforehand, which acted as a bit of a buffer."

At Moore Park Beach, north of Bundaberg, local resident Russell Stewart said the beach and dunes along a 16-kilometre stretch of coastline had been heavily eroded over the past week.

The beach erosion at Snapper Rocks on the Queensland border by Sunday. ( AAP Image: Dan Peled )

The community has been planting trees and shrubs for several years in a bid to protect the coast from erosion.

Mr Stewart said environmental groups had relocated turtle nests, but that they believed some were still washed away by the large swells.

"We've lost approximately half a metre off the top of some of the dune areas, especially towards the north, and it's moved the sand — it didn't move it back to sea, it's mainly blown it over the top and in towards the Kolan conservation park," Mr Stewart said.

"The waves came right across the top and brought sand right over the grass area [of the SLSC area] and has made more impact into the old surf club here, and the authorities really need to zone in and see what they're going to do with this area, and get moving on it before it becomes totally unsafe.

"We've lost a number of turtle nests over Oma, the turtle watch group have worked tirelessly over the last week or so to try and relocate as many nests as they could but unfortunately we have had some losses, and that's nature I suppose."