Short Oral Presentation 11th Australian Stream Management Conference 2024

Site level vegetation and sediment processes observed over a decade of river rehabilitation (#32)

Jack Coates-Marnane 1 , Brianna Heeley 1 , Ross Bigwood 1 , Vanesssa Durand 1 , Cameron Jackson 2 , Tony Costantini 2 , Julian O'Mara 3
  1. Healthy Land and Water, Brisbane, Queensland , Australia
  2. Environment & Water Quality, Urban Utilities, Brisbane, Queensland, Australia
  3. Source Protection, Seqwater, Brisbane, Queensland, Australia

The interaction of vegetation and river processes and form are a foundational element of freshwater ecosystem health. Re-establishing vegetation and rebuilding freshwater ecosystem resilience are key challenges in mitigating channel erosion risk in high risk waterways with degraded riparian condition. Repeat LiDAR capture can provide insights into the functional role of recovering riparian vegetation in influencing sediment processes. LiDAR change analysis was used to investigate vegetation and sediment processes occurring within a large river rehabilitation site on the Logan River in Southeast Queensland, over a 10 year period re-establishment of riparian vegetation. The analysis reveals the dynamics of erosion and deposition at the site, indicating there has been a net deposition of ~5000 tonnes of sediment from 2014 to 2023. This has occurred as vegetation has matured.  Cover of dominant canopy species (Eucalyptus tereticornis) is currently at ~30% with an average tree height of > 5m. The transition from a net eroding site, with no woody native vegetation to a net accreting site with maturing native vegetation illustrates the success of the rehabilitation site and provides insight into the role of vegetation on sediment processes at the site scale. River rehabilitation strategies informed by an understanding of river process are likely to result in improved outcomes across targeted ecosystem service values, such as water quality and freshwater biodiversity. Empirical evidence of the interaction between vegetation and river process can inform these strategies.

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