Matt Cowley Tauranga City Councillor

Recent heavy rain in Dunedin and Wellington shows it's near impossible for any city in New Zealand to live free from flooding.

A month's worth of rain fell within 24 hours in both cities this year. No city in NZ would have the infrastructure to cope with that amount of rainfall.

A one-in-100-year event in the 1970s is now only a one-in-60-year event by today's standards. More rain is falling within shorter timeframes – and it's forecast to continue intensifying.

The rising sea levels will make it harder for the city's pipes to drain water away – the high tide was a key issue in the Mount during the April 2013 floods.

It's a losing battle against nature if we rely solely on building bigger pipes to save us from flooding. It gives us false hope and causes complacency if people think their homes will never be flooded.

Council has adopted a new approach to enable the city to adapt to flooding, rather than try to defend against it.

This means the council will develop overland flow paths to allow water to flow into the sea/harbour as quickly as possible. We will also need to create rules to ensure people do not do stuff on their property that increases flood risk for their neighbours or people living downhill from them.

The rules may also require houses to be built well above the road height. Our roads are designed to flood, to hold water away from homes until it can drain away.

The suburb of Mount Maunganui is generally flat and will require a different response. Overland flow paths work where there is a gradient for water to flow down. But flood water in the Mount is already struggling to drain away during high tides.

I've seen different models suggesting Mauao will become an island within 100 years.

This means seawater would come up through the current pipes well before then. The longer we delay discussions on flood risk and sea-level rise, the fewer options we have to manage the risk.

The worst-case scenario would be building a seawall around the peninsular, losing our lovely golden sand beaches, as seen in this photo of Dunedin's St Claire Esplanade and main beach.

Expanding sinkholes at the St Claire Esplanade – Source: Otago Daily Times

Feel free to email me your thoughts (matt.cowley@tauranga.govt.nz), call/text me on 027 6989 548, and follow me at www.facebook.com/a.younger.voice.