Recent severe weather has exposed the vulnerability of South Wairarapa’s flood protection infrastructure, prompting Greater Wellington to accelerate its review of how the region prepares for increasingly frequent and intense flooding events.
The regional council says its immediate priority remains supporting communities affected by the recent storms, particularly those isolated by damage to the Tūranganui River Bridge, while also beginning a broader conversation about the long-term future of flood management across the lower Wairarapa Valley.
Greater Wellington Deputy Chair Ros Connelly says the council is working alongside the South Wairarapa District Council and other agencies to restore access and support recovery efforts, while acknowledging communities are seeking reassurance that lessons will be learned from the recent weather event.
The council has confirmed that a comprehensive review of flood protection in South Wairarapa is already underway. The work was initiated last year in response to expiring resource consents, climate change, environmental considerations, farmer concerns and obligations to mana whenua.
The review includes updated flood hazard modelling, environmental assessments and engagement with local communities, with a progress report due to be presented to Greater Wellington’s Environment and Climate Committee on 20 August.
Environment and Climate Committee Chair Quentin Duthie says the recent flooding reinforces the need for a collaborative, long-term approach that brings together councils, mana whenua and local residents to determine how best to manage future flood risks.
Among the issues expected to be examined are improvements to the damaged Tūranganui River Bridge, changes to road approaches and possible modifications to the river channel itself to improve water flow during major weather events.
The bridge is regarded as a vital transport link for communities south of Martinborough and along the South Wairarapa coast, making its resilience a key focus of future planning.
The review also highlights the age of the existing Lower Wairarapa Valley Development Scheme, which was developed more than 50 years ago. The scheme includes stopbanks, floodways, barrage gates, river management works and drainage infrastructure serving the Tūranganui River, Ruamāhanga River, Lake Wairarapa and Lake Onoke.
Greater Wellington Catchment Manager Pete Huggins says the recent weather event placed extraordinary pressure on the ageing flood protection system.
Approximately 400 millimetres of rain fell across the river headwaters over a 72-hour period, creating flows that likely exceeded the level of protection the existing scheme was designed to provide.
While gravel extraction remains one tool used to reduce flood risk by improving river capacity, Huggins says the design of infrastructure such as the Tūranganui Bridge must also be considered. Low bridges can restrict river flows during major floods, increasing the likelihood of water backing up upstream.
On average, around 3,000 cubic metres of gravel are removed annually from upstream of the bridge, primarily to provide material for stopbank maintenance. However, commercial gravel extraction in the area has generally not been economically viable, meaning future work may require additional ratepayer funding.
For Māori, the review carries particular significance. Flood management is closely connected to kaitiakitanga, balancing the protection of people, whenua, awa and ecosystems while recognising the cultural significance of waterways throughout the Wairarapa. Engagement with mana whenua will form an important part of determining future flood protection options and ensuring environmental restoration is considered alongside engineering solutions.
Greater Wellington says the recent storms serve as a reminder that climate change is increasing the frequency and severity of extreme weather events, making long-term investment in resilient infrastructure and catchment management increasingly important for communities across the region.
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