Key Takeaways:
- Almost 18,000 properties across Wairarapa are at risk of flooding in the event of a severe flooding event
- Climate change is expected to increase the frequency and intensity of severe weather, putting more properties at risk
- The number of properties at risk is likely to increase, with estimates suggesting that by 2110, nearly 50% of all buildings in South Wairarapa and Masterton will be exposed to flooding
- The council has conducted a detailed flood damages assessment for Masterton, estimating between $8.1m and $16.7m in damages for present day, and $21.5m and $42.3m with climate change
- GWRC is working on several flood management projects, including the Waipoua urban reach and the lower Wairarapa valley development scheme review
Introduction to Flooding in Wairarapa
Almost 18,000 properties across Wairarapa are estimated to be at risk in the event of a severe flooding event. This number was revealed by the Greater Wellington Regional Council (GWRC) following a request under the Local Government Official Information and Meetings Act. The exact figure of 17,800 breaks down regionally, with Carterton having 3100 properties at risk, Masterton having 9400 properties at risk, and South Wairarapa having 5300 properties at risk. These figures include both rural and urban properties and are set to increase due to climate change.
The Impact of Climate Change
Climate change is already changing the frequency and intensity of severe weather, and this trend is expected to continue. Lian Butcher, GWRC’s group manager environment, stated that "assuming existing schemes do not change, and at-risk properties are not retreated from hazard areas, the number of properties at risk is likely to increase." Climate change modelling suggests that the effects of climate change will increase in the future, especially as residential developments continue to be granted consent within known flood-prone areas. For example, by 2110, both the South Wairarapa and Masterton districts are expected to have nearly 50% of all buildings exposed to flooding, which represents approximately 60% of the commercial buildings in South Wairarapa and 70% of commercial buildings in Masterton.
Flood Risk in Wairarapa Towns
Four of the five Wairarapa towns, including Featherston, Greytown, Carterton, and Masterton, are at risk of flooding from major rivers in the Ruamāhanga Valley. However, Martinborough and other areas are not unaffected, with Martinborough being cut off during flood events, causing disruption to visitors and residents. The catchments on the Wairarapa coast are also not without risk, as experienced with the flooding in the Tinui area as a result of Cyclone Gabrielle. The council has conducted a detailed flood damages assessment for Masterton, which estimates between $8.1m and $16.7m for present day and $21.5m and $42.3m with climate change.
Flood Management Efforts
GWRC plays a key role in managing flood risk, including modelling, risk management planning, emergency management, and the construction and maintenance of flood defences. The council has several flood management work programmes underway in Wairarapa, including the Waipoua urban reach, which involves working with community members, mana whenua, and Masterton District Council on a preferred flood risk management option for the urban reach of the Waipoua River. The council is also reviewing the feasibility of using nature-based solutions for addressing flood risk to Masterton and the lower Wairarapa valley development scheme. Following Budget 2024, GWRC and the Ministry of Business, Innovation and Employment’s regional economic development and investment unit, Kānoa, agreed to co-fund 16 flood resilience projects as part of a nationwide initiative.
Conclusion and Future Plans
In conclusion, the risk of flooding in Wairarapa is a significant concern, with almost 18,000 properties at risk. Climate change is expected to increase the frequency and intensity of severe weather, putting more properties at risk. GWRC is working to address this risk through various flood management projects and initiatives. However, more needs to be done to mitigate the effects of flooding and protect the properties and communities at risk. The council’s efforts to future-proof the community, infrastructure, cultural taonga, and economy are crucial in preparing for the potential impacts of flooding. By working together, we can reduce the risk of flooding and create a more resilient and sustainable future for Wairarapa.