Mataura flood protection upgrade
The Mataura flood protection upgrade, completed in November 2023, has strengthened the resilience of flood defences for Mataura township and its 1,500 residents. This work enhances protection for properties, homes and businesses, helping to secure the future of the town in the face of changing climate conditions.
Following the February 2020 floods, which brought the stop banks that protect Mataura to near capacity and led to the evacuation of 1,500 residents, engineers identified areas needing reinforcement. This project focused on stabilising priority areas to ensure the town’s flood defences are ready for future events.
Key upgrades completed
The project included strengthening and extending the Boundary Creek stop bank, reinforcing the Waimumu Stream stop bank and adding rock protection to vulnerable sections of stop bank along the Mataura River above Te Au Nui Pihapiha Kanakana / Mataura Falls. Additional work included removing high-risk trees from along the stop banks and extracting gravel from the gravel island in Mataura township to prevent riverbed buildup.
Why these upgrades matter
In November 2022, engineers identified that high river flows in the Mataura River could cause erosion, potentially leading to stop bank failure and flooding of the township on the true left bank, upstream of the old Mataura paper mill. The upgraded stop banks are designed to accommodate future height adjustments, enhancing the town’s resilience to climate impacts. Removing trees and shrubs from stop banks prevents root systems from weakening these critical structures, which could lead to breaches during high flows. Additionally, trees can topple in heavy winds, creating holes that allow water to flow through, while tree debris poses a hazard during floods and can damage infrastructure.
Benefits
- Improved flood protection for Mataura township’s community, property and infrastructure.
- Future-proof design to allow for easier adaptation as flood resilience needs change.
- Funding from central government enabled work to be brought forward in the Long-term Plan and delivered at a much lower cost to ratepayers.
Looking Ahead
The next phase involves the application of 2D hydraulic modelling of the Mataura River, covering Mataura, Gore and Wyndham. This modelling will help assess stop bank capacity and inform future resilience measures. Community engagement will continue as we evaluate the best design solutions for long-term flood protection.
Funding and collaboration
This project is part of the national Resilient River Communities initiative and was a collaboration between Kānoa – the Regional Economic Development & Investment Unit and Environment Southland, with support from the Gore District Council, the Mataura Community Board and Hokonui Rūnanga. It is one of six Resilient River Communities projects that Environment Southland undertook with co-funding from the central government through the Covid-19 Recovery and Response Fund during 2021-2024.
By creating resilient river communities, we aim to reduce environmental, economic, and social impacts from flooding, making Aotearoa New Zealand safer for everyone.
