Sunday, October 2, 2022

River restoration stops thousands of cubic meters of sediment flowing over barrier reef

Twenty years ago, Brad Wedlock became frustrated with the condition of Queensland’s Mary River at Kenilworth, where each flood eroded thousands of cubic meters of farmland, releasing sediment to smother the southern side of the Great Barrier Reef.

Tree felling, sand and gravel mining and the misguided practices of the past have turned the once shady, flowing river into an erosion-ravaged waterway.

Showing the extent of the erosion in Carter's farm and how it cut into the bank.
River repair site before restoration at Kenilworth in April 2019.,Supply: MRCCC,

Fast forward to today and despite three floods this year, the once eroded banks stand strong and stable along the river’s access, which is being restored, thanks to community will and the commitment of dozens of people.

“Here this site looked terrible, there are no two ways about it; it was a terrible, terrible site. There isn’t much habitat for aquatic species such as [endangered] Mary River Cod,” said Mr Wedlock.

“It’s hugely different, housing prices are here, the site is making progress.”

A photo of upright logs in a bare river paddock in 2019 compared to similar logs surrounded by plants in 2022.
Before (above, 2019) and now… many have stopped cutting and plantings are flourishing.,ABC Villager: Jennifer Nichols,

environment at stake

Of the 35 catchments that flow onto the Great Barrier Reef, the Mary River is the fourth largest contributor of fine sediments.

But as a project officer with the Mary River Catchment Coordinating Committee (MRCCC), Mr Wedlock has seen the transformative power that community will, money and careful planning can have.

Earthmovers are working to repair the damaged edge and dump it in the fields of heaps.
River repair site during restoration at Kenilworth in 2019.,Supply: Burnett Mary Regional Group,

In 2015, earthmoving equipment began to reshape eroded sand rocks in parts of the riverbank at Kenilworth, driving rows of 6-metre-tall wood piles to slow the flow of floodwaters.

ABC Rural last visited the project in 2019, and returned with Mr Wedlock to see how uplifting the restoration project had coped with nature’s recent extremes.

A young tree with red leaves grows next to a heap of fields.
The fertile silt is helping the seedlings grow next to the heap fields.,ABC Villager: Jennifer Nichols,

Although the trees were hit by the rubble, they had strong roots and fertile silt was forming around the wood pile fields that would eventually rot.

Logs and poles on the ground next to the trees.
Flood debris hit the plants but most survived.,ABC Villager: Jennifer Nichols,

habitat saved

A ribbon water plant called Vallisneria, important to the prehistoric lungfish that swam in these waters, had survived the third largest flood on record.

“They all washed away after the 2013 floods, so the lungfish had no habitat to lay eggs,” Mr Wedlock said.

“Seeing Vallisneria still here means we may have slowed down the system enough to hang, whereas after 2013 it took three years to come back.

Green water weeds photographed in the river.
Vallisneria, or ribbon plant, is important lungfish habitat and has survived floods.,ABC Villager: Jennifer Nichols,

More than 45,000 native riparian plants have been planted on Kenilworth’s riverbanks.

Ruth and Stephen Carter worked hard to help water hundreds of people at the UB station during the height of the drought.

As native plants grow, pile fields are disappearing and 10-meter cliffs are threatening their land and livestock, now only an unpleasant memory.

A man and a woman are standing on the bank of the river, behind whom trees are growing and behind them are a pile of fields.
Ruth and Stephen Carter are thrilled with the progress of the remedial work.,ABC Villager: Jennifer Nichols,

“Every flood, the beautiful soil just kept falling into the river,” said Ms. Carter.

“We’ve lost a good 10 acres [four hectares] in 40-odd years, so this [project] certainly preserved it beyond any dream we ever had.”

With federal funding, MRCCC, Seawater, Burnett Mary Regional Group, Alluvial Consulting, Noosa and District Landcare and assistance from interested landholders, seven sites have been remedied at Kenilworth.

young tree behind a fence
Trees are growing fast at UBI station.,ABC Villager: Jennifer Nichols,

erosion repair wishlist

The MRCCC is looking to repair at least 35 more worst-hit areas along the 320-km-long river.

“If we had $50 million we could probably fix all of that,” said Mr. Wedlock.

“We’ve devised an investment strategy so it’s all possible, and we can’t do it all at once, so in the next 10 to 20 or 50 years, we’ve got work ahead of us.”

Downstream showing a river repair site which is now covered with vegetation.
The first river repair site before restoration work at Kenilworth in 2015.,Supply: Alluvial Consulting,

Ms Carter said she and her husband would strongly encourage other landholders to get involved.

“This project has been an amazing success and we are overwhelmed with the support we have received from all the stakeholders. They have all collaborated so well, it is a huge credit to all of them.”

Nation World News Desk
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