Managed retreat considered for North Canterbury village

Managed retreat is an option for a small North Canterbury settlement threatened by coastal erosion, flooding and sea level rise.

The majority of residents at the small settlement of Amberley Beach want to remain there for as long as possible, Hurunui District Council planner Hannah Shields said.

The council recently adopted an Amberley Beach Coastal Adaptation Plan after three years of consultation with local residents.

Managed retreat, was presented as a long-term option, receiving a positive response from residents earlier this year, she said.

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“The purpose of an adaptive plan is to leave all of the options open for as long as possible,” Shields said.

“It is unlikely we will ever get 100% agreement on the preferred option.”

She said 37 of the 109 property owners had offered feedback on the option of land banking to prepare for a managed retreat, with the majority in favour.

Council staff would seek feedback from the remaining property owners to get their preferences before taking any further action on this option.

The plan set out how to fund and manage a coastal bund to protect properties, as well as a series of “triggers” for when residents and the council would need to reconsider their options.

Options would include moving the bund back further from the coastline, introducing other coastal protection measures or implementing managed retreat.

Chief executive Hamish Dobbie said the bund was owned by the residents, with the council acting as the “collector of funds”.

It was first constructed in 1993 in response to coastal flooding the year before, and was extended to the full length of the settlement in 2003.

It required maintenance every few years, but has been successful at preventing coastal inundation and reducing erosion.

Dobbie said a new bund was now required, as the existing one was too close to the sea, and it would need to be relocatable as the sea level rose.

“The new bund is a bit of a game changer because it can be rolled back and it can go deeper into the sand.”

He said the “triggers” were based on the possible hazards.

Triggers included property owners being unable to obtain insurance, the cost of renourishing the bund, the impact of flood events and significant capital works being required.

“One trigger will trigger a conversation, but two triggers is an indicator that we need to implement another option,” Dobbie said.

“People’s concerns about different triggers will differ and it will be their choice.

“It we don’t have triggers we are not going to know when to have those conversations.”

The council has been consulting with its four beach communities since 2020 with the aid of “Coastal Adaptation Explorer”, a web-based tool developed by international technology firm Jacobs.

The web-based tool won an award from the United Kingdom’s Environment Agency last month.