Unlocking the Potential: The Challenge of Quantifying the Effects of Riparian Revegetation on Sediment Load Reduction (#40)
Daniel Trnovsky
1
,
Michael Cheetham
1
,
Daryl Lam
1
,
Andrew Brooks
2
,
Timothy Pietsch
2
- Waterways and Ecology, Water Technology, Brisbane, QLD, Australia
- Coastal and Marine Research Centre & School of Environment and Science, Griffith University, Brisbane, QLD, Australia
- Utility providers offsetting nutrient and sediment loads represents a huge potential funding source for river rehabilitation works. There is a need though, to quantify the reduction in erosion associated with the works. In the past this has meant that hard engineered interventions that provide an immediate and measurable reduction in erosion are favoured. It is much more difficult to quantify the impact of large-scale riparian revegetation, even though the benefit may be greater.
- A rigorous methodology was produced to quantify the benefits of catchment scale revegetation in two large SEQ catchments. The study involved analysing historical topography and vegetation canopy data, catchment wide rain-on-grid modelling and extensive post-processing and incorporating a large body of scientific literature.
- At the catchment scale, stream reaches where riparian canopy cover is less dense were found to contribute greater sediment loads during flood events. This relationship, which is consistent with previous research, can be used to indicate the maximum volume of sediment loss that can be avoided by increasing riparian canopy cover. Estimating the actual sediment load reduction in a flood event is much more complicated. Many difficulties of tackling problems like this on such a large scale were discovered including insufficient data, limited computational capacity, and dealing with the complexity inherent in large catchments.
- Though this is a strong indication that riparian revegetation reduces riverbank erosion, opportunities exist to refine the technique to quantify this more accurately. The challenges associated with doing so could only be understood by tackling the problem on such a large scale.
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