Oral Presentation 9th Australian Stream Management Conference 2018

Maribyrnong river erosion control project floating boom trial  (#100)

Zoe Samson , Michael Bain

Traditional ‘hard’ engineering solutions to address channel stability are no longer the preferred option in contemporary waterway management. Where public assets are threatened and intervention is required ‘soft’ solutions including the establishment of vegetation to provide long-term stability and habitat can be a more cost-effective use of public funds that provides multiple benefits. However, in urban catchments limited available space can make vegetation establishment, particularly on steep banks, difficult to achieve. In recognition of this issue, Melbourne Water has commenced a bank protection project trialling an innovative solution to stabilise a sheer, eroding bank of the Maribyrnong River in Melbourne’s west. The erosion of the bank in question is threatening a Parks Victoria owned shared user pathway located less than 1m from the top of bank. A lack of riparian and aquatic vegetation means that the bank is vulnerable to erosive forces exerted by fluvial, tidal and wave action. To mitigate these forces this project uses a floating boom to promote sediment accretion and the establishment of riparian and aquatic vegetation. Critical to the success of this approach is the fast establishment and colonisation of aquatic vegetation. To facilitate this, 38,000 nursery grown emergent macrophytes are being installed to the river bench behind the boom. The floating boom methodology has not been used by Melbourne Water previously. If successful, it is expected that this approach can be repeated at other locations to address bank stability and asset protection while also providing amenity and habitat outcomes. A significant advantage of this approach is that the same floating boom can be remobilised allowing the bank stabilisation work to be staged, achieving reduced overall capital costs. This project will be delivered in two stages along the Maribyrnong River.

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