A map of Nelson showing where would be affected under the council’s modelling of a one percent probability of flooding in the year 2100. Photo: Nelson City Council.

Nelson city has to ‘deal with flooding’


The threat of Nelsonians’ homes being flooded is not going away and we need to take steps to address it, according the Nelson City Council’s top planner.

Council staff were responding to last week’s front page story in the Weekly which outlined concerns from residents in The Wood over a new development that was being built more than a metre off the ground.

It would tower over the street but needed to be built that way to get through the consent process due to an increased threat of flooding over the next 100 years.

“We are not alone, there are a number of other places around the country that are facing the same issues,” says the council’s group manager strategy and environment Clare Barton.

Nelson City Council’s new hazard information projects risk all the way to the year 2100. According to the council’s mapping, swathes of the city are at risk of flooding based on a 1 per cent “annual exceedance probability” rainfall event, meaning there is a one per cent chance of it occurring every year.

This means any new build in the flood areas, which include parts of Stoke, Nelson North, Enner Glynn, Nelson South, Atawhai and The Wood, may need to be mitigated.

“This is something that’s not going to go away – either for us or anyone else in New Zealand with same situation with low lying floodable areas,” Clare says.

She says the 2100 scenario is “worst case” but council was obligated to make the hazard modelling public as soon as it had it. “If we don’t report that information and there is an event, then the community will quite rightly say ‘what are you doing about it’.”

Then council legally has to apply the information under the Building Act.

Clare acknowledges the concerns of people in The Wood who say that the new development is out of character for the street. She says that the hazard plan is yet to catch up with larger building planning for the city.