Flooding after the Ngaruroro River in Hawke's Bay burst its banks during Cyclone Gabrielle, February 2023. Photo: Supplied / Dawson Bliss
The first climate change assessment report for Hawke's Bay has been released, revealing an increased risk of ex-tropical cyclones, droughts and flooding.
It was commissioned by the Climate Action Joint Committee, made up of local and regional council representatives and tangata whenua leaders, and shows a broad range of climate change risks the region faces, and the likely impacts.
Key findings for the Hawke's Bay region
- Ex-tropical cyclones are likely to become more intense, packing stronger winds and heavier rainfall.
- Fire seasons will get longer and more dangerous, with increased risks of wildfires.
- Droughts will become more common, putting additional stress on primary industries and water resources.
- The region will see more hot days and fewer overnight frosts. This means warmer temperatures overall, which will affect everything from farming to local wildlife.
- Vulnerable populations, including those in areas of higher socioeconomic deprivation, face disproportionate risks from flooding and isolation.
- Community cohesion may be challenged as climate impacts affect liveability in certain areas.
- Access to essential services could be compromised during hazard events, with isolation risks particularly high in rural areas.
The region is far too familiar with the effects of climate change, having suffered a severe drought in 2020 and 2021, followed by the 'wettest year on record' in 2022, and then the devastating Cyclone Gabrielle in 2023.
Committee chair Xan Harding said for the first time, this report presents a full range of climate risks for Hawke's Bay.
"One of the key findings from this work is the significant level of variability and gaps in our climate datasets across the region. We have a foundation to work from with this report, but there is more to do so we can all be confident we are making climate risk-informed decisions based on consistent data that is as complete as possible."
The Hawke's Bay region covered 14,200 square kilometres, and 80 percent of that land was hill country or mountainous terrain. Often referred to as the 'fruit bowl of New Zealand', it was one of the top wine capitals of the world and grew 60 percent of the country's apples.
The lives of the region's 185,400 residents were expected to be impacted by climate change, which the report predicted would substantially alter the environmental conditions of the region in the coming decades.
Councils were working on a number of flood resilience projects, including a $176 million multi-year investment to allow communities severely affected by Cyclone Gabrielle to stay in place while new community-scale flood infrastructure was built. It was also looking at reshaping two major flood schemes in the Heretaunga Plains and Upper Tukituki catchments, and reviewing smaller flood schemes.
The report provided more information on the hazard datasets used for the assessment, including event likelihoods (Annual Exceedance Probability, or AEP) and how the modelling took climate change into account. A 1 percent AEP was an event that had a 1 percent chance of occurring each year.
The report broke the climate change risks down into the region's different districts.
Flooding in Napier, February 2023. Photo: NZDF / supplied
Napier City
Napier City was 105 square kilometres in size, with a population of 64,695. It had extensive coastal areas of housing, including beaches and Ahuriri Estuary, and was bounded by rivers to the north and south.
- Coastal flooding was a significant and increasing risk, with 71 percent of residential buildings exposed to a 1 percent AEP coastal flooding event with one metre of sea level rise.
- Three waters infrastructure was at risk by 2100 - with 26 percent of water supply pumps and 35 percent of pipes exposed in a river and surface flooding event.
- There was a high risk of businesses being isolated in river, rainfall and coastal flooding which could significantly disrupt the city's economy.
A long-awaited strategy to tackle coastal erosion was released last year. It identified 'trigger points' in four areas where more than $34m needs to be spent to protect homes.
The Hastings District covered 5229 square kilometres and had a population of 85,965. Present day river and rainfall flooding risk (2 percent AEP) was the most severe hazard for the Hastings District, with 39 percent of commercial properties and 11 percent of residential properties
exposed and 48 percent of the population at risk of isolation.
- A key issue was the vulnerability of its three waters infrastructure - with the major East Clive wastewater treatment plant, stormwater infrastructure and wastewater directly exposed.
- Coastal flooding was also increasing with climate change, forecast to impact 4 percent of residential properties by 2130.
- Landslides had the potential to isolate more than 9 percent of residents, and river and rainfall flooding posed the greatest risk to GDP.
- The district was projected to be more than 3C warmer by 2100, leading to 55 more hot days over 25C a year, and decreasing winter rainfall by 17 percent.
Central Hawke's Bay District
The Central Hawke's Bay District covered 3333 square kilometres and had a population of 15,480. The biggest risk was from river flooding, and had been identified as the most severe hazard influenced by climate change.
- 43.7 percent of commercial properties and 12.6 percent of residential homes were currently exposed to a 1 percent AEP event.
- Multiple sectors faced disruption and damage, with isolation due to landslides putting 44.1 percent of the agriculture sector at risk.
Water security was a high priority for the district, with the controversial Ruataniwha Dam being [https://www.rnz.co.nz/news/national/556408/campaign-launched-against-controversial-ruataniwha-dam-in-hawke-s-bay
resurrected and rebranded] under the government's fast-track legislation.
Ruataniwha Dam opponents pictured in 2024. Photo: Supplied
Wairoa township. Photo: Pool / NZME
Wairoa District
Wairoa had a land area of 4077 square kilometres and a population of just 8826, half of whom lived in the township.
Wairoa River posed a large threat, flooding many times in the past. The most recent was in June 2024, when about 400 properties were inundated.
- The report found river and rainfall flooding was a severe present-day hazard for the Wairoa District, and may affect 15 percent of residential properties and over 90 percent of the manufacturing sector.
- Over 81 percent of the district's GDP was earned from agriculture, which was at risk of isolation due to landslide potential.
- About 1400 residents were exposed to more than 10cm of river and rainfall flooding, and 82 percent were living in areas of high deprivation.
Funding had been approved for a $70m flood protection scheme, set to begin this year, which would create spillways for the Wairoa River to be diverted into in future floods.
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