Rock fillets are constructed adjacent to eroding estuary banks for stabilisation. Rock fillets are energy dissipating structures, which are typically built to mean high water level from locally quarried rock, although fillets may also contain other habitat enhancement structures such as timber snags, or prefabricated reef balls. The fillets are a bank parallel structure, keyed into the bank at one end and open at the other, creating an area of low hydrodynamic energy in the intertidal zone between the fillet and the bank. This area of still water encourages sediment accumulation, and the regeneration of mangroves and other estuarine vegetation, where the mangrove propagules, fish and other estuarine fauna can pass through the fillet opening.
Mangroves
Method: Hybrid, Supplementary revegetation
Supplementary revegetation: Juncus Juncus ursitatus, River club Rush Scheonoplectus validus, Mat Rush Lomandra logifolia, Weeping Grass Microlaena stipoides, Basket grass Oplimenus aemulus, Scurvy Weed Commelina, Kidney Weed Dichondra repens, Swamp oak Casuarina glauca, Swamp Mahogany Eucalyptus Robusta
Mangrove species: Avicennia marina
Hybrid structure: Rock fillet
Approach
Mangroves
Geographic context
Estuary
Organisation responsible
Gosford City Council, Hawkesbury Nepean Catchment Management Authority, Tide to Table, Ocean Watch Australia
Primary objective
Coastal protection
Coastal hazard
Erosion
Asset vulnerable
Natural
Length of coastline targeted (m)
291
Date of completion
2009
Cost ($AUD)
$274,343
Source of project funding
Local government, State government, Community grants