Nearly 18,000 properties across the Wairarapa region are estimated to be at risk from severe flooding, according to data released by Greater Wellington Regional Council (GWRC). The figures, obtained through a request under the Local Government Official Information and Meetings Act, reveal a significant and growing vulnerability for communities throughout the region.
Regional Breakdown of Flood Risk
The data breaks down as follows: 3,100 properties in Carterton, 9,400 in Masterton, and 5,300 in South Wairarapa are currently estimated to be at risk. These figures encompass both rural and urban properties, and GWRC anticipates the number will increase without intervention.
Lian Butcher, GWRC’s group manager environment, stated that climate change is already intensifying the frequency and severity of weather events. “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,” Butcher said. Climate change modelling suggests that by 2110, nearly 50% of all buildings in both the South Wairarapa and Masterton districts could be exposed to flooding – approximately 6,100 and 10,900 buildings respectively.
Commercial and Residential Impacts
The potential impact extends to the commercial sector, with estimates suggesting that 60% of commercial buildings in South Wairarapa and 70% in Masterton could be at risk by 2110. Residential buildings face a similar threat, with nearly 50% of all homes in both districts potentially exposed to floodwaters.
While four of the five Wairarapa towns – Featherston, Greytown, Carterton, and Masterton – are vulnerable due to major rivers in the Ruamāhanga Valley, GWRC acknowledges that Martinborough and other areas are also susceptible. Martinborough, though on higher ground, can become isolated during flood events, disrupting access for residents and visitors. The Tinui area experienced flooding as a result of Cyclone Gabrielle, demonstrating coastal catchments are also at risk.
Financial Implications and Ongoing Efforts
GWRC has conducted a detailed flood damage assessment for Masterton, estimating potential costs between $8.1 million and $16.7 million currently, rising to $21.5 million and $42.3 million with the effects of climate change. Comparable analyses have not yet been completed for Carterton or South Wairarapa. For context, a 2022 assessment of the broader Wellington region indicated that approximately 31% of the region’s population and buildings could be exposed to flooding during a 1-in-100-year event.
GWRC is actively involved in flood risk management, including modelling, planning, emergency response, and infrastructure maintenance. Current work programs include projects focused on the Waipoua River in Masterton, exploring nature-based solutions, and reviewing the lower Wairarapa valley development scheme. Following Budget 2024, GWRC and Kānoa are co-funding 16 flood resilience projects across Wairarapa and Ōtaki.
Frequently Asked Questions
How many properties are currently at risk of flooding in the Wairarapa region?
Approximately 17,800 properties are estimated to be at risk, broken down as 3,100 in Carterton, 9,400 in Masterton, and 5,300 in South Wairarapa.
What is driving the increase in flood risk?
Climate change is identified as the primary driver, increasing the frequency and intensity of severe weather events. Continued development in known flood-prone areas is also contributing to the growing risk.
What is GWRC doing to address the issue?
GWRC is undertaking a range of initiatives, including flood risk modelling, emergency management planning, infrastructure maintenance, and co-funding resilience projects with Kānoa.
As climate change continues to reshape the landscape, what steps can communities take to proactively mitigate the risks associated with increased flooding?
