Thames is going to come up against some “big costs” as it attempts to tackle shoreline protection.

Thames-Coromandel Mayor Len Salt said those costs needed to be assessed against the value of what’s at risk.

“We’re facing up to these challenges head-on, and doing the forward-thinking, groundbreaking work that’s required, rather than just hoping the issues somehow go away. It’s a multi-generational vision and long-term action plan.”

Work on design concepts for the protection of Thames was underway, following project work showing $1 billion in assets were at risk over the long term from the effects of flooding and storm surges associated with sea-level rise.

Protection was the preferred adaptation pathway for Thames confirmed by community consultation during the Shoreline Management project.

The three-year project examined the risks to the entire Coromandel coastline from the effects of sea-level rise.

Specific actions to manage those risks have now been assessed and ranked, with work to protect Thames among the top priorities.

The Protection and Resilience Governance Group met for the first time this month, made up of representatives from the Thames-Coromandel District Council, Ngāti Maru and Waikato Regional Council.

“We know that Thames is especially vulnerable to storm surge and flooding associated with sea-level rise, putting around $1 billion of assets in our township at risk,” Salt said.

“Thames is the economic nerve centre of our district, home to the bulk of the Coromandel’s service provision, maritime industry, healthcare and business infrastructure. It’s our duty to the entire region to ensure Thames is resilient, and able to grow, for generations to come.”

Salt said Royal HaskoningDHV would now proceed with staged design options to protect the Thames township against coastal inundation for a 1-in-100-year event.

An earlier feasibility study showed the main challenge associated with protecting Thames was the required cost and scale of any defensive structures, as many locations were low-lying.

Design work would include full hydrodynamic modelling and joint probability analysis of coincident coastal and fluvial flooding events.

The governance group noted it would be important that any protection structure connected with other stormwater and river management work.

Funding for the design work, and ensuing community consultation on design options, was allocated through the 2023-2024 Long Term Plan, with funding for the construction of protection yet to be determined.

Public consultation on the design concepts is expected in May.