The Kopurererua Stream is part of a catchment that runs from as far south as Rotorua all the way to the Waikareao Estuary in Tauranga moana. The stream runs through the Kopurererua Valley reserve in Tauranga where the stream alignment had historically been straightened for farming. Kopurererua Valley was once inhabited by the people of Ngāi Tamarāwaho. Remains of the Puketoromiro Pā and other archaeological sites are located throughout the valley.
The Kopurererua Stream Realignment project is a collaborative endeavour initiated by Tauranga City Council (TCC) with the support of Bay of Plenty Regional Council (BOPRC) and Ngāi Tamarāwaho. The project aims to return the Kopurererua Stream to a more naturalised alignment, increase connection with the surrounding floodplain, enhance ecological habitat and mimic natural sediment deposition processes. Stage 1 of the project was completed in 2006.
As part of Stage 2 of the project, Tonkin + Taylor undertook design of 1.2 km of stream realignment, south of Puketoromiro Pā. The design also included two new pedestrian bridges, a wetland for sediment capture, a woody instream habitat and a new cycleway.
Tonkin + Taylor acted as lead consultant from the initial sediment reduction options assessment through preliminary design, consenting, detailed design and construction. We also provided complete end-to-end multi-disciplinary design services for the client. This included river engineering, civil design, flood modelling, ecological input, geotechnical and structural design of the bridge abutments and foundations and construction supervision.
The design aims to enhance the stream’s functionality and environmental outcomes. To ensure that the proposed works did not negatively impact floodplain dynamics, our team assessed the stream hydraulics with a 2D TUFLOW model. The stream design was also informed by a geomorphic assessment of sediment dynamics within the wider catchment and determined the preferred sediment management options to achieve project objectives. As part of the nature-based design, elements such as woody features, stream benches, and native planting were incorporated into the design to promote ecological health and diversity.
Through involvement in the Kopurererua Stream Realignment project, we’re demonstrating our leading expertise in river engineering and nature-based design. The project aligns with our values around commitment to environmental stewardship, sustainable design practices and a collaborative approach to working with other project partners and Tangata Whenua. The project aims to enhance the stream’s ecological integrity, flood resilience, and overall contribution to the well-being of the surrounding communities.