Principles of environmental design were successfully applied to the 1.34 km diversion of Mangakotukutuku Stream. This work provided an enhanced in-stream habitat and capacity for the 100-year return period flood flow.
The stream diversion incorporated environmental features such as a three-stage channel, meanders and riffle-run-pool sequences. A riparian planting approach was used to develop a nursery crop, with interplanting of resilient flowering and fruiting species that will provide habitat for birds and shade the channel.
The diversion also involved the capture and relocation of fish from the abandoned stream. The project won the IPENZ Arthur Mead Environmental Award in 2007 and the ACENZ Innovate Silver Award in 2008.
- Hydrological assessments and hydraulic modelling
- Eco-hydraulic design of the low flow channel to provide enhanced in-stream habitat
- Fish and eel capture from the original stream and relocation
- Design of riparian vegetation for aquatic and terrestrial habitats
- Construction methodologies that maximised use of onsite materials
- Construction supervision
- Contract administration.