Matapōuri sand-replenishment update

Published on 05 July 2021

Graphic showing before and after storm works at Matapouri.

Sand replenishment at Matapouri Bay entered a new phase on 5 July 2021 and should be complete by the end of this month. 

The project is designed to copy the natural process of sand movement that existed before bridges went in several decades ago. Sand washed down the estuary into the bay and deposited along the beach, then washed into the estuary in a regular cycle.

The bridges slowed the water in the streams running through estuary, which meant that sand washed in from the bay settled in the estuary and was not re-distributed into the bay.  

Nearly 8,000 cubic metres of sand had been moved from the estuary onto the beach, when a major storm struck on 23 May.  

The storm surge washed some of the sand that had been deposited on the beach into the bay and some back into estuary and changed the route of the channels, preventing access to sand extraction areas. 

Work stopped and Whangarei District Council applied for a variation to the resource consent. The resource consent has now been approved, so work on the project can begin again.  

Graphic showing before and after storm works at Matapouri.

People have expressed concern about the sand washing back into the estuary, but our engineers are satisfied that the process is working as designed. The sand deposited on the beach prior to the storm had created a buffer during the storm, reducing the damage the beach would have suffered if the storm had happened prior to shifting the sand. 

This is a soft engineering solution that seeks to maintain the amenity value of the beach, while having less of an impact on the natural environment than a "hard" engineering solution.

This replenishment regime was designed by RS Eng and peer reviewed by LaBonte' Coastal Consultants Ltd. Prior works were done in consultation with Dr J Gibbs, an expert in coastal processes and hazards.