The role of strategic vegetation establishment in the management of disturbed coarse-grained river systems — ASN Events

The role of strategic vegetation establishment in the management of disturbed coarse-grained river systems (10810)

Elisa Zavadil 1 , Dominic Blackham 1 , Ross Hardie 1 , Stuart Cleven 1 , Misko Ivezich 1
  1. Alluvium Consulting Australia, Richmond, VIC, Australia

Since the 1980s, the role of native vegetation in river restoration has expanded well beyond ecological benefits. Restoring native vegetation along banks, the riparian zone and where appropriate in the bed, is now widely adopted in the management of long-term channel stability across Victoria, and increasingly Australia-wide.

Our analysis of 40 river systems across north-east Victoria demonstrates that vegetation can reduce stream power and associated channel adjustment in reaches where in-channel peak event specific stream power is around 200-400 W/m2. This understanding has recently been applied to the Cann and Avon Rivers in Victoria, which have been the focus of major restoration programs.  The Cann River has a large mobile sand bedload. The establishment of native vegetation has been instrumental in reducing stream power and stabilising sand deposits. Lessons from the success of vegetation establishment in the Cann River are currently being applied to the Avon River, which has a remarkable history of channel incision. Our analysis demonstrates that vegetation establishment on large gravels bars in the Avon has the potential to reduce stream power sufficiently to reduce erosion, sediment transport rates, and long term avulsion risk.

The key to successful management is to identify the current stage of channel evolution, and target vegetation establishment and other works in appropriate reaches. For example, in the Laidley Creek system (south east Queensland), we highlight reaches where vegetation establishment can assist to reduce stream power and erosion potential. Strategic investment at these locations will minimise erosion of productive floodplain (horticulture), reduce risk to roads and infrastructure, and minimise sediment delivery to downstream receiving waters including Lockyer Creek, Port of Brisbane and Morton Bay.

We propose that strategic vegetation establishment directed by an understanding of channel evolution processes and stream power provides a means to accelerate channel recovery after disturbance, reduce erosion, improve long term channel stability, and reduce risk to public and private infrastructure from river processes. 

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