Hazards mapped
A new Otago Regional Council report has mapped out which parts of Otago are most exposed to natural hazards, including floods, earthquakes, landslides and tsunami.
River and lake flooding events and liquefaction presented the highest risk across the region, and more than 30,000 people and buildings were potentially exposed.
Tsunami and storm-surge disasters remain a risk for large areas containing communities close to the Taieri, Tokomairaro, Clutha-Mata Au, Catlins and Tahakopa rivers and estuaries, where population was a factor in estimating a lower exposure of about 500 people and 1100 buildings.
Exposure means a person or building is located in an area where a hazard process might occur — not that they are guaranteed to be affected.
The Otago Region Natural Hazards Exposure Analysis was the first to cover the entire Otago region.
The analysis assessed exposure to nine key natural hazard types, using regional-scale mapping and modelling to estimate the number of people, buildings, and critical facilities such as hospitals and emergency services were located in areas potentially exposed to natural hazards.
The report identified 90 critical community facilities across the region.
Dunedin City had the highest overall exposure to flooding, liquefaction and seismic hazards, and joined Queenstown and Wanaka's urban areas with a relatively high exposure to landslides and alluvial fans.
"This work is not about predicting when an event might happen," the council's natural hazards manager, Dr Jean-Luc Payan said.
"It's about identifying where exposure exists so we can make smarter decisions about resilience, planning and investment."
The findings provide a critical foundation for the council's natural hazards prioritisation programme, scheduled to begin in 2025-26 and will help guide long-term planning and land-use decisions, emergency management, regional policy development, Infrastructure and resilience-building projects.
While no new hazard mapping was done, the report is based on years of the council's existing hazard data, available through their natural hazards portal.
The council will now use the report to identify and prioritise the most at-risk areas for further study and risk reduction work.
The natural hazards prioritisation workstream is scheduled to conclude by mid-2026.
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Otago Daily Times
05-08-2025
- Otago Daily Times
South Otago residents keen for flood-prevention action
By Tess Brunton of RNZ South Otago residents want action as they prepare to face more flooding and other hazards in the future. The Otago Regional Council is developing a strategy for how vulnerable communities in the Clutha Delta can adapt. A public drop-in session was held in Balclutha yesterday so locals could hear about the mahi (work), ask questions and tell the council what they wanted to see done. Dave Inder farms next to the Clutha River in the delta and has watched his property disappear under water more than once. "We have to make decisions according to the temper of the river. It's quite simple really, I mean you can't be complacent," he said. "It doesn't have to be local rain, it can be rain in the west and it's a huge influence on us and the people below us, they're even worse." Those downstream had a tougher time getting rid of the water as they could also face big seas and backflows, he said. Sometimes rainwater became trapped on the wrong side of the floodbanks and they struggled to get rid of it. "The Clutha wasn't really in flood but our local rivers were and the delta filled up and we couldn't get the water out. "There are pipes there that were not satisfactory, but they hadn't been satisfactory for a flood like that for many years." He has been meeting with the Otago Regional Council to solve the issue and headed to the drop in session in the 'Big River Town' for answers. "The regional council come with ideas, plans and all sorts of things, but nothing's fruited yet," he said. "Snow melt could be on the way again - so there are a few anxious farmers and we just want to know if they intend to fulfil their promises." But he was keen to work together to find solutions and said that was the way forward. Groundwater could be high in parts of the low-lying floodplain and drainage could be difficult. The area has several active faults and could also be vulnerable to storm surge or tsunamis from the Pacific Ocean. The Lower Clutha Flood Protection and Drainage Scheme drains more than 9000ha from north of Balclutha to the sea and was designed to mitigate flooding from Mata-Au/Clutha River. The council's natural hazards manager, Dr Jean-Luc Payan, said an adaptation plan was about more than flood banks and drains. It looked at how to keep hazards away from people, allow water to safely leave and, in some cases, how to get people out of harm's way, he said. "That's really the purpose of the strategy, understanding the current environment, how this environment is going to change in the future, what people value in the area, how they see their future, and how we can combine those tools to have a safe environment in the Clutha Delta," Payan said. But it was a challenge - the Clutha is a powerful body of water. The delta was at the end of the catchment that was fed from big lakes in Queenstown and Wānaka. "All that water that falls on the alpine area will end up in the Clutha." A common theme at the session was people asking if the flood protection scheme was operating as planned, he said. The council recently published a study that showed current sediment levels were not impacting the flood capacity of the river, Payan said. But business-as-usual maintenance and work would continue in parallel to the mahi on the strategy, he said. Dairy farmer Thomas Marshall lives at the mouth of the Clutha in Paretai. Flooding could leave paddocks out of action for six months, taking away half his income, he said. "It's been hard trying to get any maintenance done for years now and it's just cost us a lot of money in flooding and it just gets really frustrating," he said. He would like to see the council ramp up its efforts to maintain the flood protection scheme. Balclutha resident Stephen John said it was unreal to see the Clutha River in flood. "Last big flood we had, what was that? 1998,1999? and to see it right up the top of the river banks, right round through here... so scary." He was keen to understand the hazards facing his community. "Just to catch up with everything that's going on and how we're helping things and, yeah, how scared we should be or not because I'm living down on the flat now." Balclutha resident Pip Martin was encouraged to see the mahi under way to come up with an adaptation strategy and keep the community informed. He was worried about the maintenance of a nearby floodbank. It appeared lacking in the past, culminating fears it might fail and resulting in him evacuating during one of the last floods, he said. Payan said the strategy was in the early stages and the council was working to understand the current environment and how it was expected to change. It was similar to the work the council had been undertaking in South Dunedin, Middlemarch and Glenorchy. With the final strategy a few years away, it wanted locals to help to shape the future of their community.
RNZ News
05-08-2025
- RNZ News
South Otago residents keen for flood-prevention action
The Clutha River/Mata-Au. Photo: RNZ / Tess Brunton South Otago residents want action as they prepare to face more flooding and other hazards in the future. The Otago Regional Council is developing a strategy for how vulnerable communities in the Clutha Delta can adapt. A public drop-in session was held in Balclutha on Tuesday so locals could hear about the mahi (work), ask questions and tell the council what they wanted to see done. Dave Inder farms next to the Clutha River in the delta and has watched his property disappear under water more than once. "We have to make decisions according to the temper of the river. It's quite simple really, I mean you can't be complacent," Inder said. "It doesn't have to be local rain, it can be rain in the west and it's a huge influence on us and the people below us, they're even worse." Those downstream had a tougher time getting rid of the water as they could also face big seas and backflows, he said. Sometimes rainwater became trapped on the wrong side of the floodbanks and they struggled to get rid of it. "The Clutha wasn't really in flood but our local rivers were and the delta filled up and we couldn't get the water out. There are pipes there that were not satisfactory, but they hadn't been satisfactory for a flood like that for many years," he said. He has been meeting with the Otago Regional Council to solve the issue and headed to the drop in session in the 'Big River Town' for answers. "The regional council come with ideas, plans and all sorts of things, but nothing's fruited yet," he said. "Snow melt could be on the way again - so there are a few anxious farmers and we just want to know if they intend to fulfill their promises." But he was keen to work together to find solutions and said that was the way forward. The Balclutha sign. Photo: RNZ / Tess Brunton Groundwater could be high in parts of the low-lying floodplain and drainage could be difficult. The area has several active faults and could also be vulnerable to storm surge or tsunamis from the Pacific Ocean. The Lower Clutha Flood Protection and Drainage Scheme drains more than 9000 hectares from north of Balclutha to the sea and was designed to mitigate flooding from Mata-Au/Clutha River. The council's natural hazards manager, Dr Jean-Luc Payan, said an adaptation plan was about more than flood banks and drains. It looked at how to keep hazards away from people, allow water to safely leave and, in some cases, how to get people out of harm's way, he said. "That's really the purpose of the strategy, understanding the current environment, how this environment is going to change in the future, what people value in the area, how they see their future, and how we can combine those tools to have a safe environment in the Clutha Delta," Payan said. But it was a challenge - the Clutha is a powerful body of water. The delta was at the end of the catchment that was fed from big lakes in Queenstown and Wānaka. "All that water that falls on the alpine area will end up in the Clutha." A common theme at the session was people asking if the flood protection scheme was operating as planned, he said. The council recently published a study that showed current sediment levels were not impacting the flood capacity of the river, Payan said. But business-as-usual maintenance and work would continue in parallel to the mahi on the strategy, he said. The Clutha is a powerful body of water. Photo: RNZ / Tess Brunton Dairy farmer Thomas Marshall lives at the mouth of the Clutha in Paretai. Flooding could leave paddocks out of action for six months, taking away half his income, he said. "It's been hard trying to get any maintenance done for years now and it's just cost us a lot of money in flooding and it just gets really frustrating," he said. He would like to see the council ramp up its efforts to maintain the flood protection scheme. Balclutha resident Stephen John said it was unreal to see the Clutha River in flood. "Last big flood we had, what was that? 1998,1999? and to see it right up the top of the river banks, right round through here ... so scary." He was keen to understand the hazards facing his community. "Just to catch up with everything that's going on and how we're helping things and, yeah, how scared we should be or not because I'm living down on the flat now." Balclutha resident Pip Martin was encouraged to see the mahi underway to come up with an adaptation strategy and keep the community informed. He was worried about the maintenance of a nearby floodbank. It appeared lacking in the past, culminating fears it might fail and resulting in him evacuating during one of the last floods, he said. Dr Jean-Luc Payan said the strategy was in the early stages and the council was working to understand the current environment and how it was expected to change. It was similar to the work the council had been undertaking in South Dunedin, Middlemarch and Glenorchy. With the final strategy a few years away, it wanted locals to help to shape the future of their community. Sign up for Ngā Pitopito Kōrero , a daily newsletter curated by our editors and delivered straight to your inbox every weekday.
Otago Daily Times
31-07-2025
- Otago Daily Times
South D residents don't want ‘status quo'
Dunedin mayor Jules Radich. PHOTO: ODT FILES Clear signals have been sent about what South Dunedin people want for their future amid climate challenges, Dunedin Mayor Jules Radich says. "The No 1 thing they don't want is the status quo," he said. "The infrastructure we have got simply cannot cope with the amount of inundation that we are prone to getting — so we have to install more." Large-scale retreat because of climate change and flooding threats was also unpopular and another version of managed retreat — letting water in and relocating to raised land — was not well supported either. People wished to continue to live in South Dunedin, he said. If the least popular options were discounted, a mix of what remained — making space for water while keeping the "liveable, workable" land dry — was what they favoured. Immediate action to enhance drainage infrastructure was key, which was why the council approved an additional "pipes and pumps" package in its 2025-34 long-term plan, Mr Radich said. The mayor's comments came after a report from the South Dunedin Future programme about community engagement results relating to a hazard risk assessment and seven approaches for adaptation. The programme is run jointly with the Otago Regional Council and it is principally aimed at establishing a comprehensive long-term plan for adapting to climate change. Feedback about the potential approaches was received from more than 1200 people and organisations. An option described as "space for water" was the most preferred overall. There was "mixed support" for several other options. "This suggests an openness from community and stakeholders to different approaches for managing risk and adapting to the impacts of climate change," the report for councillors said. An initial shortlist of three approaches is expected to be available this month. The regional council discussed the South Dunedin Future report last week. City councillors had a wide-ranging discussion on Wednesday about the feedback, the property market, insurance, risk and climate adaptation. Cr Christine Garey said there was a strong public mandate for change. Cr Brent Weatherall said the full options for adaptation were "mainly cost-prohibitive" unless central government came on board, but this was "clearly not yet on the horizon". Cr Carmen Houlahan said hazard information appearing on Lim reports was causing significant concern for some property owners. Cr Lee Vandervis — the only city councillor who voted against noting the report — criticised "planning for its own sake".
