Thames Protection and Resilience Project

The protection of Thames is a high priority for our district, after the Shoreline Management Pathways project showed that $1 billion in assets in the township are at risk over the long-term from hazards associated with sea-level rise.

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Thames Protection and Resilience Project aims to manage the risks to the Thames area from coastal hazards such as flooding and storms, which are expected to worsen as a result of climate change and sea-level rise. The initiative is part of the Shoreline Management Pathways (SMP) planning project, launched in 2019 to address risks along Coromandel’s 400 km coastline.

Through the Shoreline Management Pathways project, 138 unique adaptation pathways were developed, with Thames identified as a high-priority area due to $1 billion worth of assets at risk. The proposed design for Thames protection includes the construction of barriers, such as stopbanks, which will be adapted over time to accommodate a projected sea-level rise of 1 metre over the next century.

The project is a collaboration between Thames-Coromandel District Council, Ngāti Maru, and the Waikato Regional Council, alongside local communities and other iwi.

Update: Friday 28 March 2025
River flooding integral to Thames protection

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Latest modelling has confirmed river flood management must be integrated into any solution to protect Thames from the hazards associated with sea-level rise.

Over 100 people attended a public meeting on 24 March to receive an update on the Thames Protection and Resilience project. The project is an outcome of the Shoreline Management Plan, which identified sea-level rise risk management priorities for our district.

“We live in a changing world, and we have a responsibility to confront these challenges, and to keep you updated and informed about the complexities,” Mayor Len Salt told the meeting.

He chairs the project’s governance group which includes iwi, Thames-Coromandel District Council and Waikato Regional Council  representatives. The project’s current design approach is to use barriers to prevent coastal flooding over the next 100+ years, adapting in stages to a potential sea-level rise of one metre.

Rick Liefting from Waikato Regional Council presented an update on recently completed river modelling work. The model assessed flood hazard from water coming off the ranges into Thames’ streams and channels during a significant weather event.

While the integration of river flood management with the proposed sea defence was likely, further modelling was required to better understand the issue.  The modelling showed the proposed coastal protection from Karaka Stream to the Toyota factory is unlikely to cause adverse effects on river flooding. This is because the floodwater from Karaka stream mostly flows north and there is a relatively low level of overflow flooding from Hape stream. The trapping of river floodwater by the coastal protection is unlikely to be an issue for this area.

For the area north of Karaka Stream, which is about a third of proposed area for protection, the picture changes. “If we have a bund in that area, the likely scenario is that without pumping, the structure would trap river water behind it, effectively creating a bathtub,” our Council's project lead Amon Martin said. “But pumping that volume of water would require pumps bigger than what are currently on the Hauraki Plains, so there’s a lot more work to do to figure out an appropriate response for that area.

“The river and coastal systems act together and probably shouldn’t be separated when it comes to thinking about solutions,” he said.

Any proposed integrated solution and associated costs will go to public consultation as part of the next Long Term Plan review.

The project governance group will also recommend that our district Council formally request that the Waikato Regional Council consider including coastal protection for Thames in the existing Waihou Valley Scheme.

The next steps for the project will need to be carefully considered, including the need for further technical work, the preparation of an investment business case, and any subsequent planning for the implementation of preferrred physical works to inform future Long Term Plans of both councils. In the meantime, both councils are committed to a programme of stormwater infrastructure maintenance and management to help manage flooding risks. This work includes river and drainage inspections, clearing debris and regular maintenance.

Public updates will be provided as progress on roles and responsibilities, and proposed solutions, continues.

Previous updates

Coastal protection design

Progress has been made on getting a better understanding of the coastal protection design parameters, and eliciting community feedback on how protection might blend with existing amenities (such as the walkway and small gauge railway).

Public meetings in 2024 presented various concept designs for protection against a half metre of sea-level rise, and a one in one-hundred-year storm. This level of storm is becoming more frequent along our coastline, and puts Thames at significant risk of flooding.

“Everyone involved in the project is also keen to explore additional nature-based solutions that will offer another layer of protection to our town,” said project lead, Amon Martin. “These solutions include things like shell banks, oyster islands and chenier ridges, which could bring a range of benefits, including as habitats for birds.”

Meanwhile, Richmond Villas Retirement Village has proposed partnering with our Council to deliver the section of stopbank protection associated with its property. The proposed partnership includes Richmond Villas leading the engineering, design and construction process, and covering all associated costs. It’s hoped construction on this section can begin in early 2025.

Fact-finding has been completed to guide roles and responsibility discussions with Waikato Regional Council, including a review of the Waihou Valley Scheme’s objectives and rating system.

Governance meeting February 2025

The Thames Protection and Resilience governance group met in mid-February 2025 to receive updates on project work to respond to the risks to Thames from both coastal and river flooding.

The governance group includes iwi, Thames-Coromandel District Council and Waikato Regional Council representatives. Members met on Wednesday 19 February to discuss current coastal protection design, new modelling work on river flood risks, and the need for an integrated response to both coastal and fluvial flooding. 

“The ongoing work to plan for Thames protection has identified quite clearly that it’s not just coastal inundation we need to look at, there’s also river flooding threats that need to be integrated into the project,” governance group chair Len Salt told the meeting. “We now need to work through how these components work together, the impact on expected costs, and how we share the responsibility appropriately with other authorities, including Waikato Regional Council.”

The protection of Thames is a high priority for our district and is one of the outcomes of the Shoreline Management Project (SMP) pathways. The SMP project showed that $1 billion in assets in the township are at risk over the long-term from hazards associated with coastal storms and flooding caused by climate change and sea-level rise.

The project’s current design approach is to use barriers to prevent coastal flooding over the next 100+ years, adapting in stages to a potential sea level rise of one metre.

“We’ve significantly progressed the coastal protection design and our understanding of what’s required for the foreshore,” said project lead Amon Martin. “But that’s only one piece of the puzzle. The river modelling work raises a number of challenges which means we’re still some way from being able to give certainty about the total cost of protection, and which agency or authority is best placed to take the lead on different parts of the plan.”

A public meeting will be held on Monday 24 March. It will cover:

  • Why coastal inundation is not the only issue the project needs to address. River flooding threats are also a concern and must be incorporated into the project.
  • An overview of the challenges associated with fluvial (river) flooding, including recent modelling work assessing the risks associated with flooding from streams.
  • More detailed information on the varying risk profiles for different areas of Thames.
  • An update on challenges of cost estimations. Expected total costs remain uncertain, largely due to the challenges in managing river flooding. However, we will discuss the scale of investment required specifically for coastal protection.
  • A discussion on how coastal protection might be integrated with fluvial protection. There will be an opportunity for feedback on this topic.

“We’re all committed to working together on this,” Len Salt told the governance meeting. “Our partners around the table are working with goodwill to share information and plan together on this difficult and complex challenge.”

He said any funding implications would need to progress through thorough consultation processes, but it is too early in the process to make any of these decisions.

Supporting documents from February's governance group

 

Flooding risks from streams

Work to understand flooding risks from Thames’ streams, or fluvial flooding, is close to completion. Final modelling reports on the river risk component of the project are expected in early 2025. The results will then be presented at a public meeting in February 2025, along with a wider project update.

The proposed protection design looks to integrate nature-based solutions, such as a chenier ridge, to boost resilience and create habitats. The project team has also undertaken preliminary catchment modelling to assess the flooding risks of Thames’ streams.

“We need robust, effective and long-lasting solutions," said project lead Amon Martin. "So, one of our challenges is to ensure we thoroughly understand all the intersecting risks. "These include fluvial flooding risks and the likely effectiveness of pumping stations and related mitigation proposals.” 

Background

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

Have a look at our Shoreline Management Pathways project pages to find out more about this process, including information and maps all of all our coastal communities around Thames-Coromandel district, including Thames.

A governance group to progress the Thames protection work met for the first time in February 2024, made up of representatives from our Council, Ngāti Maru and Waikato Regional Council. A further meeting is taking place at the end of July 2024.

“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,” says our Mayor Len Salt, who is chairing the Thames Protection and Resilience Governance Group.

“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.”

Royal HaskoningDHV is working on design options to protect the township against coastal inundation for a 1% AEP storm over the next 100 years. An earlier feasibility study showed the main challenge associated with protecting Thames is the required cost and scale of any defensive structures, as many locations are low-lying.

Design work will include full hydrodynamic modelling, and joint probability analysis of coincident coastal and fluvial flooding events. The governance group notes that it will be important that any protection structure connects with other stormwater and river management work. 

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

“We’re going to come up against some big costs, but those need to be assessed against the value of what’s at risk,” says our Mayor Len Salt. “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.” 

For more information visit our Shoreline Management Pathways project page.