Bank erosion was occurring due to wave action at high tide. Rock fillets were installed on top of an existing low grade seawall. Each fillet was 60 tonnes with an average height of 1m, which was 1m lower than the bank height. This low height was chosen due to logistical constraints, however it ultimately prevented effective erosion control. 2.5 years later moderate sediment deposition had occurred, though mangrove stabilisation and bank stabilisation were poor. Only 3/7 fillets had mangrove recruitment (average recruitment 1/10m3). The project is generally not considered a success. Possible reasons include sediment supply, sediment retention, seed supply, coarse grained material and fillet height.

Mangroves

Method: Hybrid

Mangrove species: Avicennia marina

Hybrid structure: Rock fillet

Hybrid structure height (m): Changes relative to bed level. Top of fillet is built to 200mm above mean high water at this location

Hybrid structure width (m): 2m base

Hybrid structure length (m): 20m