Napier, post-Gabrielle. Photo: RNZ/ Tess Brunton
A new report has revealed large swathes of Napier will be at risk of seawater flooding in the next 75 years.
The council says now that it has this information, it is obligated to include it on Land Information Memorandums (LIMs) - meaning new builds and renovations will be subject to stricter rules.
The research came as part of a report, Clifton to Tangoio Coastal Inundation, jointly commissioned by Napier City Council, Hastings District Council and Hawke's Bay Regional Council.
Coastal inundation maps showed the potential impacts of seawater flooding in the year 2100, developed by environmental and engineering consultants at Tonkin and Taylor and peer-reviewed by NIWA.
The maps showed areas which, over the next 75 years and beyond, could potentially flood from seawater during an unlikely extreme weather event.
They were modelled on predictions showing worst-case-scenario sea level rise both during a 1-in-100 and 1-in-50 year flood.
The maps showed the worst-affected places would be the industrial area of Pandora, Poraiti, the areas surrounding the estuary, and three streets back from the seafront along Marine Parade, with flood depths over a metre.
Napier Mayor Kirsten Wise said in a press release the research would help the city prepare for the effects of climate change.
"We welcome this modelling and mapping because the more information we have about natural hazards, the better we can plan. This information will help us make sound decisions about future infrastructure investment."
Map showing how flooding might happen in Napier in the future. Photo: Tonkin & Taylor/ supplied
It was a reminder that all coastal communities in New Zealand must continue to adapt and challenge the status quo.
"What works today may not work in years to come."
The goal of the mapping was to inform decisions such as setting minimum floor heights and planning future infrastructure - and it fulfilled the legal requirement set by central government to map coastal hazard risks (Building Act 2004).
Map showing how flooding might happen in Napier in the future. Photo: Tonkin & Taylor/ supplied
New builds and renovations would benefit from having the modelling in place, as floor levels will be set to account for potential inundation impacts, and councils would consider the risks when issuing building and subdivision consents.
Napier had already put in place some protection measures such as raised gravel barriers, stormwater networks, gravel bunds and pumps.
Other councils have made similar moves, including on the Kāpiti Coast - where residents appealed against the report, accusing its writers of unreasonably using worst-case scenario estimates in their calculations.