Impact Review of Sand-Deflection Groyne in Port Motueka, New Zealand
In 2010 the Van Dyk Family Trust commissioned an ongoing project in Port Motueka, New Zealand
This project has focused on the review of potential effects resulting from the construction of a 700 m long by 1.5 m high geotextile groyne/breakwater in 1995-96. The structure intended to deflect southerly directed sand from the Motueka Spit offshore in order to maintain a navigable channel to Port Motueka. The scope of the review has been limited to information associated with the Resource Consent for the construction of the groyne, a review of historical positions of the spit and coastline and basic hydrodynamic modelling. Following construction of the 700 m long structure, the Motueka Spit has increased in length and width and is in a location further offshore than previously recorded by bathymetry surveys and aerial photography since 1881. As a result, Jackett’s Island has experienced ongoing erosion that has translated in a southerly direction following the growth of the spit.
