Oaky Creek was a torrent of water as flooding associated with Tropical Cyclone Debbie ripped down the channel and spilled over the banks. Multiple landslides at the top of the catchment added gravel loads into the creek which were then spread across adjacent cane land.
At some sites the creek moved more than 10 meters, taking away arable land and leaving vertical drops of more than six meters. The movement and changes of the creek has landholders and stakeholders concerned for their farmland, infrastructure, and the safety of operations around the creek. The remaining bare and unstable riparian areas are highly prone to future erosion if they are not stabilised.
To assist in stabilising the creek, Reef Catchments was successful in obtaining National Disaster Relief and Recovery Arrangement (NDRRA) funding to remediate and build resilience into Oaky Creek. Alluvium Consulting was engaged to undertake a stability assessment and hydrological modelling of a priority nine kilometers length of Oaky Creek.
Three community consultation events were held to engage with landholders and stakeholders and to draw out information on the history, current uses, and future requirements of the creek.
The consultation and assessment highlighted that more than 60,000m3 of sediment has been lost along the creek during the past nine years, with historical flood-driven straightening of the channel, and vegetation loss from disease along sections of the creek during the past 50 years.
Alluvium’s assessment has provided prioritised sites for rehabilitation including bank re-profiling and rock reinforcement. Alluvium has also recommended a comprehensive and structurally diverse revegetation program to complement other works to join up and improve riparian vegetation along Oaky Creek. Once vegetation has become established it will help to bind sediments, buffer water flowing past, and reduce future erosion.
“The right catchment vegetation and riparian management can reduce the speed and volume of water entering the river system and the speed at which water drains from an area. This greatly reduces flood heights and speeds in downstream catchments.” Ref Qld Gov Wetland Info.
Works, planned to begin during the coming months, are to be completed before the end of December 2018. The project is expected to see up to 4 000 tonnes of rock armouring and 50 large woody debris structures built to stabilise the channel and more than 10,000 plants will be planted along the creek.