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.
