‘Vicious erosion cycle’: Millions of hectares of topsoil impacted by outback flood

A environmental group says intervention was needed to begin the long process of repairing flood-affected land in Western Queensland and the Lake Eyre Basin.

A Queensland natural resource management body said they are now beginning to see the true impacts of last months’ flooding which caused tonnes of silt and sediment to slide onto protected wetland in the Lake Eyre Basin.

More than 13 million hectares were impacted by floodwaters scouring topsoil and eroding gulleys and an estimated 8.3 million hectares are at risk of weed spread, including prickly acacia, parkinsonia, rubber vine and invasive cacti such as jumping cholla and mother of millions.

Desert Channels Queensland chief executive Leanne Kohler said they had a long road ahead with the repairs forecast to cost tens of millions of dollars.

“We’ve seen major gully erosion requiring significant earthworks to fix, silt deposits 20 to 40 centimetres deep and a severe loss of grasscover,” Ms Kohler said in a press release.

“Thick layers of sediment have not only killed kilometres of grasscover – many landholders have lost topsoil, which means vital seed banks, nutrients and soils are all gone.

“The Lake Eyre Basin is a vital breeding bastion with significant wetland, agricultural land and watercourses, and without intervention this land will not easily recover.

“Without soils, grass can’t grow back, and without grass, there’s no pastures, no biodiversity, nothing to hold together soils and protect our iconic Lake Eyre Basin from eroding further.

“It’s the beginning of a vicious erosion cycle.”

Desert Channels Queensland operations manager Geoff Penton said a restoration technique, developed near Winton after the 2019 floods, could be the solution to repairing the flood-damaged region describing it as a “tried-and-tested model”.

“A large-scale ground-cover recovery project in Channel Country will not only reduce topsoil loss for graziers, but also protect significant lakes and wetlands in our iconic region,” he said in a press release.

“Ground-cover restoration through weed control, watercourse fencing and feral animal management, alongside seeding and spelling efforts, will dramatically reduce future erosion.

“A project would be a win-win-win for the Lake Eyre Basin, combining conservation values with investment to preserve our region’s vital soil, water, pasture and biodiversity resources.”