Quantifying the Benefit of Vegetation in Reducing Sediment Delivery to Morton Bay (#60)
Michael Cheetham
1
,
Dan Trnovsky
1
,
Daryl Lam
1
,
Andrew Brooks
2
,
Tim Pietsch
2
- Water Technology, West End, QLD, Australia
- Griffith University , Gold Coast
- Ongoing accumulation of fine sediments and associated nutrients in Moreton Bay poses a significant threat to the aquatic ecosystem health of Moreton Bay, a Ramsar wetland of international significance. Research over the last 25 years has identified that sediments are primarily derived from channel erosion in the Lockyer and Bremer River catchments. To address the threat, this investigation identifies the degraded channels in these catchments, where remediation would reduce sediment loads to the Bay by 50%.
- The investigation focused on two large catchments; the Lockyer and Bremmer and required the development of a method to quantify the expected erosion in each river reach. This involved the use of multi-temporal LiDAR data, catchment wide sediment sampling and analysis, Rain on Grid hydraulic modelling, and vegetation density and coverage data.
- Using a relationship between vegetation coverage and erosion, the analysis indicates that:
- For Lockyer Creek, revegetation of 130km of channel could achieve a 56% reduction in sediment generation.
- For the Bremer River, revegetation of 89km of channel could achieve a 54.4% reduction in sediment generation.
- The investigation developed and justified a reliable method to identify effective areas where riparian remediation will achieve the desired reduction in fine sediment export. The method allows for a quantification of potential erosion associated with future high flow events and the achievable reduction in erosion sediment export if foliage projected cover, with a canopy height greater than 5m, was increased to 90%.
Download Full Paper