Horizons Regional Council’s Rachel Keedwell: Flood protection model unsustainable

Surveying the damage to the Pohangina River caused by Cyclone Gabrielle.

Opinion

If Cyclone Gabrielle had tracked 50km further west and hit the Horizons region with its full force, would we have been prepared? As part of our role in emergency management, our team is modelling this scenario so we can determine what may be required to be prepared for a similar event.

When Gabrielle hit, Horizons’ river monitoring network provided advance warning of where flooding could be expected. The models predicted the Rangitīkei River would be high by the time it reached the bottom of the river at Tangimoana. This meant an evacuation plan was ready to go and people were on site to assist in case evacuation was necessary.

What is harder to respond to is the short and heavy rainfall events that will occur more frequently with the impacts of climate change, like the event that caused the Auckland floods. Similarly, the heavy rainfall that caused the flooding last month in Marton and Whanganui was not even on the forecast and essentially happened with no warning.

These events are much harder to prepare for but are the reason we need to be thinking in advance about what we can do as communities – for example having a plan if evacuation is required and supplies at home to be self-sufficient for a few days.

One thing that has been brought sharply into focus by Gabrielle is that our current flood protection model is unsustainable. The existing (and ageing) flood protection infrastructure was originally funded by central government but the huge costs of maintaining this infrastructure are now falling entirely on ratepayers, including the never-ending cycle of storm damage repairs.

Many of our flood schemes will have no money left in reserve once the Gabrielle repairs are carried out. This is fine if we don’t have another large event for 20 years, but what happens if the next big event is in two years’ time? Some Government funding was announced in the recent Budget but this is a drop in the bucket compared to what is needed.

This will be an area our council will need to seriously consider in the 2024-34 Long-term Plan process and have conversations with our communities about.

Areas of land that are earmarked for development, but have not yet been built on, have gone underwater in weather events this year. If these developments go ahead and houses are built despite this knowledge of the risk, then that to me is very irresponsible. Poor planning in the past has created the current risks but there is no excuse if we continue to make those same mistakes – even if district planning rules technically allow development.

And unfortunately, it will be buyer beware if purchasing one of these houses because there is no guarantee any flood protection will be constructed after the fact. I strongly encourage anyone buying a house to do their research on both river and surface flooding via our district advice team at horizons.govt.nz.

The resource management reforms should help with this development issue through spatial planning processes but that is some years off. There will be some difficult conversations about how we decide where we as a community will build and maintain our flood protection and where we need to seriously consider retreat.

These conversations will need to include how we can work with rivers and allow them room to move rather than continuously fighting to constrain them – because we will eventually lose that battle. Looking long-term will help us shift to a sustainable and more effective method of protecting our communities and it’s never been as important to do this as now.

• Dr Rachel Keedwell is chairwoman of Horizons Regional Council.