Security camera captures moment family flee their Twyford home and the Ngaruroro River breaches stop bank after Cyclone Gabrielle. Video / Iain Trotter
There was so much silt he was not sure if it was possible for it to all be removed, or if it was a good idea.
Orchards and vineyards have been badly damaged by silt and floodwaters. Photo / RNZ, File
“What the river silt tends to do is build river terraces. And over time, given a generation or two, they turn into very nice free draining fertile soils.
“And those terraces move their way up above the river - the taller the river terrace, the less likely you are to flood next time.”
Work to assess the damage and next steps for the places worst affected by the cyclone and recent weather bombs is still being done.
Climate change makes storms more damaging, and more likely.
Climate Sigma climate economist and modeller Belinda Storey said homes in floodplains that were inundated regularly, or quickly, would likely keep getting struck again and again unless expensive protections were built.
Belinda Storey says more is known about the topography of the moon than parts of Hawke's Bay. Photo / Zahrina Robertson, File
“If a house has been devastated in these events, then it doesn’t make a lot of sense for us to rebuild that house.”
While it was understandable to want to rush to help people rebuild after a crisis, in the long run it could make things worse because it encouraged people to remain in harm’s way, Storey said.
Laser topographical mapping - called LiDAR - gave details down to the centimetre and could be used to help accurately plot flood risk, Storey said.
It had been done extensively in Te Tai Rāwhiti , but in Hawke’s Bay it was a different story, she said.
“We currently have a better understanding of the topography of the moon than we do of Hawke’s Bay.”
Storey said it was far cheaper to invest in nationwide laser mapping, than pay for it by letting nature reveal the places most vulnerable to flooding after the next inevitable weather bomb.
Paul Paynter. Photo / Paul Taylor, File
Victoria University Emeritus Professor of public policy Jonathan Boston said tens of thousands of people might need to move out of harm’s way by the end of the century.
He warned there were no easy answers but there needed to be a national conversation, and cross-party consensus, about the fairest way to split costs.
“I appreciate this is very, very difficult for people have to come to terms with, but we must,” Boston said.
“For many people in the last year or so in New Zealand … climate change has arrived, and it’s been devastating, and we need to take that really seriously.”
Victoria University of Wellington public policy expert professor Jonathan Boston. Photo / Supplied, File
Victoria University economics of disasters and climate change chair professor Ilan Noy said any compensation package needed to be as unattractive as possible to dissuade holdouts.
“You [could] end up with the … worst of all possible worlds where … because some people decided to stay, you still need to try and protect the communities … provide them the services: water and electricity and so forth, but it’s a much-diminished community.”
Noy said insurers needed to allow homeowners to take payouts and rebuild elsewhere out of harm’s way.
An inundated property in Esk Valley during Cyclone Gabrielle. Photo / Greg Miller, File
Cyclone Recovery Minister Grant Robertson is already indicating some devastated areas may not be rebuilt, with a decision to be made, possibly within a month.
Meanwhile, the Government is part way through creating a nationwide plan for managed retreat, with decisions from Cabinet due later in the year.
Boston said with the danger of sea level rise also looming, countries faced unprecedented challenges, and durable plans on how to respond were needed.
“If we don’t have them, we will flounder,” he said.
“We will run the risk of undermining public confidence in our democratic institutions, potentially with profound implications for the future of democracy.”
Finance Minister Grant Robertson visits the flooded Redclyffe substation. Photo / Warren Buckland, File
He recently co-wrote a paper on managed retreat for the Environmental Defence Society.
Central government would need to provide a substantial part of any compensatory package, Boston said.
He believed the government should negotiate to purchase the properties of those affected, with a cap on the total amount that any particular property owner could receive.
People’s principle home should get greater compensation than baches or rentals, he said.
“These are detailed matters that really need to be thought about very carefully because almost anything you do is going to have both positive and negative implications.
Raging flood waters flipped this car upside down at a house in Shaw Rd, in Napier's Esk Valley. Photo / Warren Buckland, File
“And whatever [the government] might propose … [for] pre-emptive managed retreat, there are going to be serious problems.
