Wyndham flood protection upgrade
Environment Southland is upgrading existing stop banks in Wyndham township (population 550 +). The aim is to provide a more robust and continuous flood defence scheme for Wyndham by focusing on areas that present the most risk to the community in the event of flooding in the near term.
Wyndham flood protection upgrade is a Resilient River Communities project. Resilient River Communities is a joint initiative between Kānoa - the Regional Economic Development & Investment Unit, regional councils, and local authorities focused on developing and upgrading vital river management and flood protection schemes in Aotearoa New Zealand.
By having resilient river communities, we hope to minimise environmental, economic, and social damage caused by flooding – making New Zealand safer for everyone.
Extensive flooding in Southland in February 2020 saw stop banks in Wyndham tested by floodwaters to near capacity. Emergency management and council staff, alongside Southland emergency services, evacuated 4500+ people throughout the Mataura catchment, including residents in Wyndham.
The Wyndham stop banks were built in the early 1970s following widespread flooding in 1968. They were raised again after severe flooding hit the region again in 1978. The stop banks guard the town against the Mataura River to the north, west and south and its tributary, the Mimihau Stream, to the north.
The plan is to widen, strengthen, and infill sections of the existing stop banks in the township of Wyndham.
Priority is being given to construction two new sections of stop bank to close gaps in the flood defences at Ferry Street, and linking the Mimihau stop bank to higher ground.
Remedial work on the existing flood protection scheme will be undertaken based on:
- Geotechnical investigation
- 2D Hydraulic modelling
- Eyewitness and photo documentation indicating potential failure points
Inspection, repair and extension of the existing culverts, headwalls and flat gates and associated flood protection infrastructure will also be undertaken along with the remedial works.
- Greater protection for homes, businesses, and communities in Wyndham in the near-term
- The design of the proposed works is 'future proofed', meaning that the height of the upgraded stop banks could be more easily raised in the future, if appropriate
- Work completed with central government funding assistance
Project status (1 October 2022)
- Preliminary tree work completed
- Survey, geotechnical and engineering design work completed
- Engagement with landowners in progress
- Community engagement underway
- Stockpiling of additional stop bank materials for 2022-23 construction season
- Finalising consents and approvals for the work to proceed
- Tendering of contracts
- Commencement of further tree work in the vicinity of the stop banks and staged earthworks in spring-summer 2022, with the total work programme spanning two summers