Predicted intense summer weather could dramatically alter an island and waterway off the Sunshine Coast, according to locals who know the area well.
The Bureau of Meteorology has told Sunshine Coast News there could be some powerful events during the next few months, including the possibility of a cyclone near the region.
When ex-cyclone Seth was offshore in early 2022, it caused a tidal breakthrough at Bribie Island that ultimately altered tides in the Pumicestone Passage and filled the Caloundra Bar with sand.
Another cyclone could further destabilise the area, according to Caloundra Coast Guard commander Roger Pearce.
“All bets would be off if we were to get a tropical cyclone or two,” Mr Pearce said.
“In early predictions, we could be in for two or three this season.
“The water temperature needs to be 26.5 degrees to support a tropical cyclone. The water temperate has gone over the required temperature four or five times within one week this month.
“Any storm surge associated with a tropical low or tropical cyclone – typically over half a metre on top of the (high) tide – could play havoc with the current fragile state of Bribie Island and a number of potential breakthroughs.”
Spring tides appear to have affected the passage during the past month or two, ‘flushing out’ the northern end of the waterway, which was partially clogged with sand after the 2022 event.
“We had some large tides recently and as we move into late December and early January the king tides will help (water flow) greatly,” Mr Pearce said.
But he was unsure if the old Caloundra Bar, at the very northern end of the passage, would ever reopen.
“The spring tides provide a great flushing action, but nothing will replace the flow you would get if the old Caloundra Bar was reopened,” he said.
“That would give the area a complete flush and remove all the sediment that has built up over the past few years.
“Only time will tell if this will ever happen again.”
Passage photographer Doug Bazley, of Bluey’s Photography, captured images of the Bribie Bar and the northern end of the passage earlier this month, and said water appeared to be flowing more freely with spring tides.
“The bar and a big sand spit (within the passage) have really changed, allowing a lot more water into the northern end of the passage,” he said.
“The big sand spit only had a small opening before, letting minimal water into the northern part of the passage.
“But it has now opened right up. Water is pushing a lot of sand further north to the old Blue Hole basin, but at the same time giving the northern end a good flushing.”
He said the area was changing with minimal influence, so it could be particularly vulnerable in an extreme weather event this summer.
“We haven’t really had any big weather conditions to cause this (water movement),” he said.
“With the cyclone season upon us I think there will be many changes that none of us will be able to predict.”
Regular photo of the day contributor to SCN, Lesley Evans, provided photos of a still pool of water at Happy Valley near the old Caloundra Bar.
“I believe that the colouration of the sand when the tide goes out shows that something needs to be done,”
“Water flows in and then flows out but no flushing occurs (there).
“It needs to be filled in with sand or an entrance to the sea dug so flowthrough and flushing occurs.”
A spokesperson for the Department of Environment, Science and Innovation said there was “no real update” to the situation in the passage during the past month.
“Our monitoring shows that wave wash-over events will likely continue (on Bribie Island).”
“While the formation of new permanent tidal channels are possible, they’re highly unlikely to occur without extreme weather events.”
DESI has repeatedly stated that the area is a “dynamic” coastal environment, which is “undergoing natural changes over time”.
Its monitoring also showed the width of the breakthrough was “relatively stable for at least six months” at 1.2km.
The spokesperson also reminded people that the breakthrough areas and moving sand formations remain part of the Bribie Island Recreation Area.
“Visitors should be mindful of the regulations in the area with respect to dogs, fires and camping, and should check park alerts for the latest information,” they said.
