Catchment Solutions has successfully completed on-ground works at the Collinsdale erosion remediation project site. The primary erosion remediation site is located at the Collinsdale Station, which is situated on the southern side of the Fitzroy River, in Garnant, approximately 30km from Rockhampton. The 450ha cattle property is situated within the Louisa Creek catchment and has been identified through Paddock to Reef modelling as contributing the 10th highest load of sediment to the Great Barrier Reef Marine Park from the Fitzroy basin area.
The Reef Trust IV Erosion Remediation project area included the rehabilitation of large-scale gully erosion, using earthworks to reshape and fill the erosion scar, with the project, including;
- Approximately 20,000m3 of material being moved and reshaped,
- Over 8km of river and streambank fencing to be installed,
- the construction of a large farm dam (excavated to provide fill for earthworks and to provide an additional off-stream watering point), and,
- the installation of over 8 off-stream watering points, as cattle restricted from accessing water directly from Louisa Creek and the Fitzroy River.
Figure 1. Before (left) and after (right) images taken from a drone of the primary project site, showing significant gully erosion in pre-construction image and cut, fill and reshaping earthworks in post-construction image.
With the completion of earthworks in late 2019, the site has been irrigated, seeded, mulched and revegetated to reduce rainfall impacts on the rehabilitated gully area.
Over eight kilometres of fencing has been installed along Louisa Creek to allow natural regeneration of the riparian vegetation and over 8 additional watering points (troughs and piping) have been installed to allow alternative water supply and reduce grazing pressure on the lower catchment of Louisa Creek. An additional 4 kilometres of fencing has also been installed to protect the rehabilitated sites and to improve rotational grazing practices.
Following an excellent wet season in early 2020, the site has revegetated with pasture grass and seedlings are now well established. Monitoring of the site in May 2020, demonstrated successful rehabilitation following the first wet season. Further tube stock plantings and weed management is planned for the next 12 months.
Figure 2 Rehabilitated Avulsion Gully (April 2020)
Figure 3a to b. Before (left), after construction (middle) and following revegetation (right) images taken from around the primary project site, showing significant erosion issues in pre-construction images and fill, reshaping earthworks in post-construction images and commencement of effective revegetation by May 2020.
Figure 4. Before (left) and after (middle) image taken from a drone of the large farm dam excavations, around the primary project site, with spillway formalisation works still being completed in the image in the middle. The image on the right is after construction following a good wet season.