Te Rūnanga o Koukourarata is a legislated authority (Ngāi Tahu Claims Settlement Act 1998) and represents the many hapū and whānau on the northern bays of Te Pataka o Rakaihautū Banks Peninsula. The hapū has a long history in the area, including the landing of the waka taua Makawhiu. The harbour at Koukourarata is known as Te Ara Whānui o Makawhiu. The entire area is culturally significant and sustains the hapū and whānau that live there. To ensure this continues, Te Rūnanga o Koukourarata has a 500-year strategy, Te Mahi Tamariki – for our future generations. The embodiment of the strategy has three pou: Tāhua Taiao (Environment), Tuakiri Taketake (Indigenisation), Toiora Takata (Health and Wellbeing). Protecting the environment and people will always be the forefront for the hapū. Te Rūnanga o Koukourarata will be a part of the leadership in climate action for the future generations.

Mō tātou, ā, mō kā uri ā muri ake nei.

For us and our children after us.

Christchurch City Council recognises the rangatiratanga of Te Rūnanga o Koukourarata over its whenua and is working in partnership to plan for impacts on public assets and places of value.

Purau-Port Levy Road, Fernlea Point Road and Pa Road are local roads that provide important access to Koukourarata Port Levy. Around 200–350 vehicles use these roads each day during the peak holiday season. The roads provide an alternative access route for some communities and are used for agriculture, logging activities, by pedestrians and seasonally by tourists. Sections of the roads, and also the less-used Wharf Road and Old Port Levy Road, are vulnerable to coastal hazards, particularly Pa Road which is only metres from the high-tide line in places.

Historically used to export goods alongside the transportation of animals and passengers, the wharf is still a highly valued asset in Koukourarata Port Levy. It’s mainly used for recreation now, but it remains accessible and could be used in the event of an emergency if roads in and out of the area were closed. The wharf already floods during spring and king tides, and rising sea levels and the larger storms expected in the future will only increase the impacts of this.

At the head of Port Levy Bay tidal mudflats and inter-tidal zones support a range of native salt-tolerant plant species, such as sea rush and glass wort, and shellfish, such as cockles, which are significant for their mahinga kai value. The mudflats merge into a diverse saltmarsh ecosystem as the land rises. These ecosystems are nationally rare and threatened because humans have changed many of the natural environments they live in. Together with the shingle fans that form around stream outlets across the bay, the saltmarsh provides important habitat for the estuarine birds and seabirds that feed and roost in the area. A range of bird species can be found here at any time, including the South Island pied oystercatcher and the reef heron, a nationally endangered species.

It’s important to note that there are other assets and places of value in Koukourarata Port Levy that are not public. Close collaboration with Te Rūnanga o Koukourarata will be needed to support the long-term management of the area.

Rising groundwater, coastal flooding and coastal erosion all pose risks to Koukourarata Port Levy. It’s also significantly impacted by stream flooding, the effects of which will only get worse as sea levels rise. The images below show that as sea-level rise happens, the area will experience deeper flood events over larger areas. The floodwater may also stay around for longer as groundwater levels rise and it gets harder for surface water to drain away into the soil. Areas at risk from erosion are likely to lose land at a faster rate as sea levels rise.

It’s important to note that while we have a good understanding of how coastal hazards will impact us, it’s hard to predict the rate at which sea levels will rise further in the future. The rate of change will depend on global greenhouse gas emissions and what impact this has on our climate. If different tipping points are reached, it’s possible we’ll see sea levels rise much more quickly. That’s why it’s important to have a plan in place for the future of our coastal communities.

The wharf and parts of Purau-Port Levy Road, Fernlea Point Road, Wharf Road and Pa Road are all at risk from coastal hazards. If nothing is done, coastal hazards will increasingly cause road interruptions and closures, making it harder to move around and in and out of Koukourarata Port Levy. The area around the shorefront will become damper as sea levels rise and flooding occurs more often. The wharf will be increasingly affected, becoming unusable during flood events and high tides. The parking area and public toilet that support the public use of the wharf will also be affected.

It’s important to note there are other important assets and places of value in Koukourarata Port Levy that are not public. Close collaboration with Te rūnanga o Koukourarata will be needed to support the long-term management of the area.

The Coastal Panel has considered the workable options that would address the risks to each of these assets. These options are set out in the section titled ‘Adaptation pathways’.

Sometimes the way we decide to manage one asset will have an impact on how the other assets could be affected by coastal hazards and the options we have available to manage those risks. In Koukourarata Port Levy, the decision to protect the roads in their current location or to move them out of the hazard zone will have an impact on other assets.

1. Hold the line

We could flood-proof and protect the wharf and at-risk sections of road in their current locations for several decades. This option could be used to buy a bit more time or a lot more time, depending on the amount of investment before we need to switch to a ‘work with nature’ approach and move away from coastal hazards.

Long term, holding the line would involve a combination of coastal protection, raising the road and improved drainage. Some of these options might impact the ability of water from the streams, or heavy rain events to drain away from behind the road. Improved drainage, such as new or larger culverts, may be needed to ensure private properties aren’t affected.

Over time, the mudflats, beach and foreshore will be lost in some areas as sea levels reach the hard edge of the road.

The existing wharf could be flood-proofed by raising the deck above predicted future flood levels. This would increase its resilience to coastal hazards for a time and ensure it was available as a way to access the community in the event of an emergency, particularly if the roads were closed. The land to either side of wharf would need to be armoured to protect against erosion and ensure the wharf is accessible. Armouring this section of foreshore would also provide some protection to the land directly behind, but it may increase the rate of erosion in neighbouring, unprotected areas.

A new flood-proof and removable toilet, or a temporary one, could be built in a location with less coastal-hazard risk.

2. Work with nature

In time, it may be better to move at-risk sections of the road away from the shorefront and out of the hazard zone, to help keep access to the community. This option could be used when it becomes harder and more expensive to maintain the roads – likely in around 10 to 20 years from now – or when actions to protect the road (‘hold the line’) become less effective.

Building new sections of road will be very expensive and difficult. To build new roads, we’d need to purchase private property at some point in the future, which the Coastal Panel and the Council acknowledge could be a difficult process for the landowners. Relocating Pa Road would mean crossing over Māori land or Papakāinga zones, so it could only be considered as an option with the support of Te Rūnanga o Koukourarata.

Once new access is built, existing roads could either be removed, or maintained to a lower standard until no longer workable. Removing the existing sections of road would provide space for the mudflats, beach and foreshore to move inland as sea levels rise, meaning they’d continue to provide ecological and recreational benefits.

In time, a new wharf could be built further inland, giving it more resilience against flooding and keeping it available as a way to access the community in the event of an emergency. Under this approach, the foreshore would not be armoured, providing it with space to naturally adapt to rising sea levels.

The toilet would be removed from its current location. There would be an option to build a new, removable or temporary toilet outside of the hazard zone (away from the foreshore) if a suitable location could be found.

Both of these approaches come with their own opportunities, risks and costs, and they may need to be used at different times or could be more appropriate for some assets than others. Importantly, regardless of what we do, it’s going to get harder, more expensive and environmentally disruptive to keep public assets in this area, particularly near the shorefront where coastal erosion, flooding and groundwater all pose a risk.

The adaptation pathway map below shows that at a certain point – likely around 10 to 20 years from now – changing conditions will mean action is needed to avoid increasing maintenance costs and disruption. As we near this point, we could look to flood-proof the roads to different levels to buy us a bit more time or a lot more time, depending on the type and scale of work.

Alternatively, we could look to move the roads sooner, or at a point when flood-proofing the roads becomes less effective.

*We don’t yet have enough information to understand exactly what the cost of this option would be.

The adaptation pathway map below helps to show that at a certain point – likely around 2 to 10 years from now – changing conditions will mean maintaining the wharf is no longer workable and upgrades will be needed. As we near this point, we could flood-proof the wharf to extend its useable life, but how long this lasts would depend on the type and scale of work carried out. Alternatively, a new wharf could be built sooner, or at a point when the cost to maintain the existing wharf becomes too great.

*We don’t yet have enough information to understand exactly what the cost of this option would be.

The adaptation pathway map below helps to show that the location of the current toilet isn’t suitable and that something will need to be done. Even at current sea levels, king tides cover the area surrounding the toilet.

We could look to build a new toilet on higher ground along the shorefront and flood-proof it to buy extra time. Alternatively, we could look to relocate the toilet further away from the hazard zone or remove it altogether.