New research from James Cook University shows the degree of coastal degradation along the Townsville coast

Adjunct Professor with James Cook University Eric Wolanski said his research shows there are two main issues that are affecting the coast, one is sand erosion the other is mud which is polluting the bays around Magnetic Island.

(Left) Volunteer researcher Chris Hopper and JCU Adjunct Professor Eric Wolanski with their paper on the environmental degradation of the Townsville coast.

A new research paper from James Cook University has shown the degree of coastal degradation along the coast of Townsville.

JCU adjunct professor Eric Wolanski said there were two main issues, one is with sand, the second with mud.

Sand on the coast is constantly moving by currents and waves but the sand is not being replenished by this sand movement due to it being trapped in the Ross River Dam behind the port’s seawalls.

Professor Wolanski said this is the reason for the beach at Rowes Bay being starved of sand.

The beach at Pallarenda is being starved of sand leading to severe erosion.

“So you got a city council who dumps sand and that sand is flushed out, moved in a few weeks not years and you end up with a sand cliff,” he said.

“It has a vertical wall, the sand moves what’s left up to Pallarenda.”

Professor Wolanski’s research also shows a sand spit at Pallarenda, which was likely caused by the Three Mile Bridge choking the peak outflow currents, preventing the outflow to break through the sand spit.

“If you look underneath there is a v notch, so that has slowed down the flow of the tides,” Professor Wolanski said.

“It doesn’t have enough power now because the flow rate with the tide and the flood is really reduced.”

Professor Wolanski said there were solutions to this.

“For Rowes Bay, for the beach erosion issue is to keep that sand in is a groyne, like the one at the Strand,” he said.

“You’ve got to redo the foundation of the bride so that it can let the full flow of the tide. You need to dredge a channel through the sand spit, where it was before so it can through and the sand of the sand spit over time will just go away.”

(Left) The photo on the left shows no sand spit where the photo on the left shows the sand spit that has formed.

Townsville City Council is undertaking a review of the Shoreline Erosion Management Plan for Rowes Bay to Pallarenda, with the community able to have their say on the process.

The review aims to establish a plan which will ensure Rowes Bay and Pallarenda’s foreshores' sustainable use and management over the next 20 years.

“The Rowes Bay and Pallarenda stretch of coastline holds a lot of value to our community for its recreational, scenic and spiritual value, which is why it’s essential for Council to continue to manage it safely,” acting mayor Ann-Maree Greaney said.

“Council has been dedicated to delivering coastal system solutions along Rowes Bay and Pallarenda for more than two decades, managing the beach system as a whole and enhancing resilience at Pallarenda by building the beach there during the past 25 years.”

Cr Greaney said the council was committed to continue the management of the ecosystem in a way that keeps it healthy for the future.

“To do this, we need to update our Rowes Bay to Pallarenda SEMP to ensure we have an effective framework in place,” she said.

In the bays around Magnetic Island in the 1960s, the water visibility was up to eight metres on average.

Today, the visibility is less than one metre due to degradation due to mud.

The turbid Ross River plume during a flood, hugging the coast and moving north longshore (12 January 2008). IT does not reach Magnetic Island and thus it is not responsible for the water clarity having decreased from 8m in the 1960s (before dredging) to 1m nowadays.

“What’s happening, the Port will dredge a channel, but dumps that mud just in the bay to the east of the channel, “ Professor Wolanski said.

“And it’s 400,000 metres cubed, so it’s not a little amount, it’s a big amount.”

Professor Wolanski said there is a solution to these problems and ports in Europe and the United States have successfully adopted these solutions, which is to bring the mud on land.

“Of course it’s messy, it’s mud, and there’s salt in it, so you can build land, or you can build a seawall and you can dump the mud in it, so It’s not on land but in the water, but in water which is basically next to the coast, ” he said.

“Very shallow, you can dump the mud over time it will become hard and you will have new land, but at least you don’t send the pollution to Cleveland Bay and the Island.”

A spokesperson with the Port of Townsville said that maintenance dredging is undertaken to remove accumulated sediments from the shipping channel to maintain safe navigational depth.

A spokesperson with Port of Townsville said the port was involved in work undertaken by GMRPMA which considered a range of different dredge placement options for Queensland ports. Contracting Pty Ltd. PICTURE: SUPPLIED.

“Sediment removed during maintenance dredging is placed at sea in a designated area outside the Great Barrier Reef Marine Park under permits approved by both Federal and State government agencies,” the spokesperson said.

“Townsville Port was involved in work undertaken by GMRPMA (Improved Dredge Material Management for the Great Barrier Reef Region) which considered a range of different dredge placement options for Queensland ports.

“The study found beneficial re-use or land disposal at the six ports within the World Heritage Area are unlikely to be viable as a strategy for overall management of maintenance dredge material in the long term.”

Originally published as New research from James Cook University shows the degree of coastal degradation along the Townsville coast