Managed retreat talk needs to happen soon - engineer

6:27 am on 4 March 2023

It is not too early to talk about retreating rather than rebuilding after Cyclone Gabrielle, according an environmental engineer who helped move an entire Australian town to higher ground after catastrophic floods.

More than a dozen people died when a metres-high wall of water flooded Grantham, west of Brisbane, in 2011.

A swift decision was made to up-sticks and essentially move it up a hill with the help of government and council funding. The rebuild was complete within a year.

Now, people living in the West Auckland beach settlement of Muriwai face an uncertain future, with many homes red-stickered. And it is the same for flood victims in Hawke's Bay, such as those in the devastated Esk Valley and in some areas of Tairāwhiti.

Environmental engineer Jamie Simmonds was project director for the Grantham move, but is in Aotearoa at the moment. He said the retreat conversation needed to start sooner rather than later.

Flood damage in the Esk Valley in Hawke’s Bay.

An Esk Valley house surrounded by deep silt, and damaged by a shipping container that crashed into it during the floods Photo: RNZ / Tess Brunton

"In my experience people need to start thinking about it pretty early on. When people get hit by a disaster - certainly in the case of Grantham in Australia - they're really hopeful for answers quickly, and you have a fairly short window of opportunity with those people, to pull them together and help 'em out," Simmonds said.

"So although you need to focus on the recovery efforts ... and the response, having those conversations early, particularly internal to councils or government - having those discussions, figuring out a bit of a plan, and then getting in front of the communities that are willing interested as soon as you can.

"I don't think there's any too early - it's just about whether a community is willing to have those conversations."

Home flooded up to its roof in Rissington, Hawke's Bay.

A Rissington house inundated during the flooding in Hawke's Bay, on 14 February. Photo: Supplied / Adam Hedley

Simmonds said it should be clear which places should be having those conversations.

"Any time you have a situation where people's lives are in danger in particular, you're having to do rescues and people could potentially be traumatised for life with these things, I think it's something that is good to consider.

"In the case of Grantham we had a significant loss of life, we had people being pulled off of roofs with helicopters and probably some similar situations to what New Zealand's experienced over the past few weeks.

"In those cases when people can be heavily traumatised, I think those are situations when communities might want to look into relocation - that was certainly the case in Grantham, that the community really stepped up and wanted to be part of this before we really had a plan in place."

Clean up in Wairoa following Cyclone Gabrielle.

Much of Wairoa was flooded, with the town cut off by road due to storm damage. Photo: RNZ / Jonty Dine

In Grantham, land to relocate to was available, but some of the New Zealand communities now facing uncertainty about their future are unique coastal areas or places with highly productive horticultural land that would be hard to find a similar match for.

But Simmonds said considering whether to organise a relocation or how to do it was not a 'one size fits all situation'. Every community and every situation would be different.

"There's always a case of how does this community want to respond, and what things do they need to get them through it."

Plan about how to relocate Grantham arose and developed as the needs were explored and land was found, he said: "You find those opportunities. Other communities may not necessarily have land available that's suitable, but there might be other options available to them, and those are the kind of things that you've really got to get in the weeds and really talk to the community about - that's the most important element, is listening to what they have to say. Because they've been living there for a long time and they may know things that you can't pull off Google Maps. You've got to be responsive to their needs."

The Grantham relocation was complete within a year. Could that happen again?

"We had our first ballot to allocate land six months after the flood, and we had workshops with the community to masterplan the new site within about two months after the flood, so one thing that we recognised is that communities that are willing, they will do anything to move forward.

In some cases they were running planning meetings and workshops three times a week, because that's what people wanted, he said.

"When you have a community like that and you have leadership up top - the mayor out in Grantham was a very strong leader ... and when you have those elements that are so important you can move forward very quickly.

"But you need to be able to respond to that community, so you need to be able to understand what they need and then you need to be able to deliver."

So, when it comes to managed retreat, who should pay? Where is the line between personal responsibility and the collective bearing the cost?

"In terms of who pays, we've got to get to a point where we realise that everyone pays for it anyways, regardless of the response that you choose - managed retreat just brings that cost forward," Simmonds said.

"Do you want to keep pulling people off roofs with helicopters? Because that gets very costly and its not good for a community. That's how we weighed it up.

"And I think in the years since then Grantham has flooded a number of times, but the [emergency] response there has been minimal because we've dealt with the issue."

The aftermath of massive flooding that swept through the Esk Valley during Cyclone Gabrielle. The river's normal path can be seen running down the right of the valley.

The Esk Valley was flooded, properties swamped and people had to escape onto roofs when the river burst its banks. Photo: RNZ/ Sally Murphy

Simmonds said he was being kept busy during his trip to New Zealand by people wanting to learn more about his experiences and assessments of what could be done, and he welcomed it.

"There's been a lot of meetings that have popped up since the cyclone.

"There is certainly a lot of interest, and I'm happy to talk to anyone, anytime, about my experience, and if it can help communities in New Zealand then I'm happy to have that chat."

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