Rehabilitating eroded banks for fish habitat outcomes in Upper Tweed River Estuary

24 Jul 2023

As part of the Fisheries Habitat Restoration Program, 550 metres of riverbank along the Tweed River has been rehabilitated to improve fish habitat. The project used a composite log-rock revetment design incorporating both logs and rocks embedding them into the riverbank to provide bank stability and areas of intertidal vegetation.

Additional rehabilitation works carried out include:

• installation of root balls and snags to provide immediate fish habitat
• 500m of fencing to exclude cattle from the riparian zone
• revegetating 0.5ha with local native species to help stabilise the bank and restore riparian function.

Senior Land Services Officer, North Coast Local Land Services, Shaun Morris said composite log-rock revetment offers several advantages over other erosion control methods.

“Primarily the combination creates a flexible and durable structure that can withstand the forces of water and provides natural-looking riverbank protection,” said Mr Morris.

“Additionally, the use of reclaimed logs and rootballs makes this method environmentally friendly by repurposing material that would otherwise go to waste.”

The structure works in a number of ways to protect riverbanks:

Erosion prevention: The primary purpose is to resist the erosive forces of waves, currents, and flowing water. The rocks absorb and dissipate the energy of the water reducing its erosive power.

Slope stabilisation: The revetment acts as a protective layer that stabilises the slope of the riverbank. By placing the rocks strategically, they create a stable surface that resists erosion and prevents slumping.

Wave dissipation: When waves or boat wash approach the revetment, the structure absorbs their energy and breaks their force, reducing the impact on the riverbank.

Sediment trapping: Revetment can also play a role in trapping sediment. As water flows over the rocks and logs, it slows down allowing sediments carried by the water to settle and accumulate behind the revetment. This can help replenish intertidal vegetation.

Coast and Waterways Team Leader, Tweed Shire Council, Tom Alletson said the 500 metres of river bank revegetation at this site is already thriving.

“In the long term, these trees will provide multiple benefits to the river environment, particularly fish, and Tweed River recreational users. We are particularly grateful to the land owner who supported the project and set aside grazing area for the tree planting,” Mr Alletson said.

“These works will help increase the complexity and abundance of intertidal fish habitat in the Tweed River Estuary by preventing the loss of bank stability caused by cattle grazing, re-establishing riparian vegetation, and creating instream habitat.”

This project is supported by North Coast Local Land Service in partnership with Tweed Shire Council, through funding from the Australian Government’s Fisheries Habitat Restoration program.

This project is part of the larger Fisheries Habitat Restoration Program in which North Coast Local Land Service will deliver five projects to restore the health and functionality of fisheries habitats across the region.

Find out more about this Natural Resource Management project.