Sea level rise: Hawke's Bay set to move sooner on coastal erosion measures

Coastal communities in Hawke's Bay could be hit by high sea level rise in the future, leaving them in the lurch.

Residents and authorities are hard at work trying to find solutions, but there is debate about the right steps to take.

The conversation is being brought up after new data found much of Aotearoa will get sea level rise twice as fast as previously thought.

Westshore, in Napier, may become one of the worst affected places in Hawke's Bay. It hardly existed before the 1931 earthquake, as much of it was under the ocean.

Now, with the arrival of this week's report, that could happen again, as Hawke's Bay Regional Council principal engineer José Beya warned.

"These effects of these subsidence rates, if they continue at the same rate or higher in the future, it means that we might have to start adapting earlier than we thought," he said.

The new data indicated a sea level rise of about four to five millimetres per year, he said.

The council had taken control of a strategy to mitigate the issues along the coastline from Clifton to Tangoio along Hawke Bay.

"So the medium to long term would be to continue mitigating erosion here, but adding controlled structures," Beya said.

"For example, a groyne that helps retain the sediment, or an offshore reef or some sort of hard structure that helps retain the material here."

He said there were still lots of questions about so-called managed retreat - or moving people away from living by the coast.

That could put pressure on authorities to buy properties that are at risk. The council has not yet finalised its assessment on the issue.

Airport has 'robust protections in place'

Hawke's Bay Airport is beside Westshore. Its chief executive, Rob Stratford, wanted time to thoroughly review the sea level rise data before being interviewed.

But in a statement, he said he was confident the regional council was "well-informed and actively planning for sea level rise impacts".

"Hawke's Bay Airport has robust protections in place and we will continue to work closely with our partners to ensure those are resilient into the future."

He did not specify what those protections were.

Some properties in Hawke's Bay that are at risk are what is known as the H18 in Haumoana near Cape Kidnappers - 18 homes which are feeling the effect of being by the coast.

One of the residents, Jane Fitzgerald, said there were constant issues, and her property often got covered by stones which had to be cleared by diggers.

"Well, we do have a mass of sea surges where we have erosion," she said.

"Some properties are actually affected more than other properties, we do have periods of time where the walls that are there are damaged quite severely."

There is a costly defence solution the residents wanted to get over the line, which they were figuring out how to finance.

Fitzgerald said it was a "continuous sea wall which will give that security to the homeowners along the coast".

But managing director of research organisation Climate Stigma Belinda Storey said options such as managed retreat must also be considered.

"Communities there [in Hawke's Bay] have expressed a very strong desire to have hard or soft defences built to hold back the ocean," Storey said.

"But what we know is, that only matters for a period of time - holding back the ocean isn't something you can do long term - you can do it on a temporary basis."

Insurance Council chief executive Tim Grafton said insurers could not just pick up the tab either.

"The transfer of risk to insurance does not reduce the risk, so that means that if you continue transferring risk to insurance it's going to do nothing unless we build resilience."

That could be a suite of options such as managed retreat, defence, as well as managing social disruption, harm to people's wellbeing, cultural sites and the environment, he said.