What those affected can expect from managed retreat in flood-vulnerable areas

Residents and business owners whose properties have been destroyed by Cyclone Gabrielle face an agonising wait to see if they will be red-zoned.

The government has spent years working on still unfinished plans for managed retreat, yet it said it would have answers for the areas that were worst affected by Gabrielle in about a month.

Residents and experts approached by RNZ give their views.

'That area should be red zoned' - Pakowhai resident

Wayne and Lynn Simpson from Pakowhai, north of Hastings, lost everything in Cyclone Gabrielle.

Rivers burst their banks, drowning their home, their bed and breakfast business, vehicles, livestock and fruit trees in metres of contaminated floodwater.

The couple smashed through the roof of their two-storey shed in Pakowhai to escape flooding, before they were rescued by helicopter, during Cyclone Gabrielle.

Wayne Simpson said someone could have been killed.

"The future for that area should be red zoned to the point where no one can inhabit that area ever again," he said.

"There's no amount of stopbank repairs and things that are going to make that area safe."

Read more on Wayne and Lynn Simpson's cyclone experience and the aftermath

'Let's make it easy for people' - call for compassion

The government, insurance industry and local councils will decide if red zones are needed, with input from the Cyclone Recovery Taskforce headed by Sir Brian Roche.

Sir Brian said residents, iwi, and business people would have input.

Engineering firm Pattle Delamore Partners' climate change leader Dr Chris Cameron said first and foremost those worst hit must be treated with care.

"From the government or from the agency side, from the insurance side as well, perhaps having a single point of contact ... where ... they're not having to go and tell their story again and again to different agencies [and] organisations," Cameron said.

"Let's make it easy for people there that have already suffered. Let's not have them suffer again, and again, through actually trying to get what's fair."

Tight timeframe and huge amount to decide

Within a month authorities need to decide which properties are too risky to rebuild, whether people will be made to abandon their homes, and decide on a plan made for those with little-to-no insurance.

The government has already spent years wrestling with these complex issues as part of the still unfinished nationwide managed-retreat plan.

Could a mini-version of the programme be done well in a month?

"No. Well not robustly in that timeframe, it's just very compressed," environmental engineer Dr Rob Bell said.

"But I recognise too that [decisions are needed], even if it is [just] a work plan."

Managed retreat expert and Victoria University Emeritus Professor of public policy Jonathan Boston said laying this groundwork and giving residents a timeline would be a good start.

"Those are the key sort of high level issues that I think the government will want to try and address," Boston said.

"The implementation of the policy may well take many months, indeed it could take in some cases, years. But hopefully, it will be possible to implement within months, not years."

Compensation a tightrope

The question of compensation needs to be finely balanced.

Too little opens the prospect of litigation, while too much risks setting an eyewatering precedent for the nationwide managed retreat programme.

"Who's going to meet the difference between the insurance payout and the valuation of their property?" Boston said.

"Will it be some combination of central and local government?

"I rather suspect that given the enormous cost that particularly the councils in Northland, east coast of the North Island areas will be bearing, they will not be in a position to contribute."

For residents who want out, answers cannot come soon enough.