Springdrift Gully Repair

Vegetation that was compromising an old gully diversion structure at ‘Springdrift’ in the Mulloon Catchment has been cleared by Green Army participants as part of the Mulloon Community Landscape Rehydration Project.

Originally built 40 years ago to prevent severe erosion in the gully below, the diversion gully had become choked with Kunzea erocoides making it inefficient and actually causing erosion.

The Green Army has re-opened the channel and used the removed materials to add surface roughness to the gully which slows water flow and helps protect newly established plants from grazing animals.

Channel, log and brush weirs have also been used on the channel floor to trap sediment, with plantings of Lomandra, Poa and Kunzea providing long term stabilisation of the site. Further plantings will take place this spring to increase structural and species diversity.

The Mulloon Community Landscape Rehydration Project is being conducted by The Mulloon Institute with the aim of rebuilding natural landscape function and resilience for the entire Mulloon Catchment. The project currently spans 23,000 hectares and involves 20 local properties.

Thanks to the project’s various supporters, including the Australian Government’s Green Army and 20 Million Trees programs.

This is an old diversion channel built by Soilcon nearly forty years ago to starve the flow from severely active gully erosion below. While the ‘roughness’ of shrubby vegetation is very useful in creeks to help to reduce stream velocity, the establishment of dense Kunzea ericoides in this location was doing such an efficient job that it had caused the channel to overtop, reinstating significant erosion consequences below. The Green Army team have brushcut and re-opened the channel so that it will once again function as planned.

The Kunzea material from the channel has been put to good use, packed within the runnels on the side of the gully. The surface contact and roughness of this material helps to slow flow and reduce further erosion, while the branches also help to protect newly established vegetation from grazing by native and exotic wildlife.

On the floor of the channel, log and brush weirs will help to retain any mobile sediment. Greg and Taylor can be seen transplanting Lomandra, Poa and Kunzea that will provide the long term stabilisation of sediment on the site. Further tubestock planting will take place in spring to increase the structural and species diversity.