To see if the council had invested enough to prevent the level of destruction seen in 2004, Local Democracy Reporting sat down with Horizons Regional Council chief executive and Horizons group manager of catchment operations.

New Zealand has always been prone to flooding, but extremes such as Cyclone Gabrielle in 2023 and various weather events across the motū, including this week’s incoming tropical cyclone, were just “a little taster” of climate change, one of Aotearoa’s leading climate scientists Sam Dean said.

February was the first time all of Horizons region had been placed into a state of emergency since 2004’s indelible flood event, which hit much of the lower North Island .

Dean said a region’s vulnerability to flooding was an “interplay” between what mitigation methods the councils chose to invest in, the amount of money spent , and the increasing risk of extreme weather.

Large investments have been made into strengthening vulnerable areas, but Horizons council staff were concerned the scale of future weather events could be bigger than 2004 andthe risk of events happening more frequently was now much higher.

Had flood prevention work not been done by council in the last 20 years, council chief executive Michael McCartney said the weather event two months ago would have been a “damn sight worse and the mountain would be that much higher to climb now”.

Acting as controller during the 2004 floods and having “water pouring through his home”, McCartney understood how scary these events could be and how they could leave communities feeling powerless.

2004’s flood was a catalyst for significant investment in flood protection methods, infrastructure such as stop banks, erosion work, and civil defence responses across the Central District.

Effective and proactive flood investment from council “would pay for itself in a single day” when a big weather event occurred, Horizons group manager of catchment operations Jon Roygard said.

Much of Horizons’ work on flood protection had environmental return and was planned with the next generation in mind – those who would have to continue modifying infrastructure to adapt to Aotearoa’s changing environment.

McCartney said councils across Aotearoa had to “accept the fact that you can’t fight nature forever”.

“All the interventions you put in place, all your best endeavours, can be taken away again in five minutes by another event.”

Dean said the area controlled by Horizons was in a stronger position than regions who had not experienced a one-in-100 year flood, as “things tend to change after an event” and councils and communities were forced to respond.

The 2004 flood was understood to be one of those one-in-one-hundred-year events, but Dean said it was likely that within decades these events would become more frequent because of climate change.

“The easy rule of thumb is that you might see a halving. A one-in-100-year flood would be more like a one-in-50-year flood.”

That was yet to occur, but with the trajectory the world was on due to rising temperatures and subsequent rising sea levels, people stood “to lose quite a lot of what we value”.

Climate change was just one issue and despite being able to adapt in the short term, Dean was concerned such extreme weather could go on so long that other issues “become irrelevant”.

Climate change predictions and figures were included in Horizons recent flood vulnerability mapping to ensure at-risk townships were prioritised for mitigation methods and coastal townships at risk of sea level rise were properly managed.

LDR is local body journalism co-funded by RNZ and NZ On Air.