Te Hapū o Ngāti Wheke Inc is the Papatipu Rūnanga legal entity that represents Ngāti Wheke, the hapū with manawhenua status over the Whakaraupō basin and surrounding areas as outlined in the Port Cooper Deed. This entire area is culturally significant to Ngāti Wheke and sustains the hapū. Te Hapū o Ngāti Wheke has a strategic plan, a key part of which is the protection and enhancement of the whenua, moana and awa. Ngāti Wheke hopes to be a part of the leadership in climate action for 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 Ngāti Wheke over its whenua and is working in partnership to plan for impacts on public assets and places of value.

The inter-tidal mudflats and cobble beach in Purau add to the overall ecological value of Whakaraupō Lyttelton Harbour, providing important habitat for sea and estuarine bird species. The mudflats are also home to shellfish and cockles, which are significant for their mahinga kai value.

The beach in Purau is highly valued by locals and visitors for recreation. As sea levels rise, there’s a risk that both the beach and mudflats - and their ecological and recreational values - will be lost, unless room is made for this environment to shift inland as conditions change.

Purau Avenue, Camp Bay Road and Purau-Port Levy Road are all vulnerable to coastal hazards. Purau Avenue and Purau-Port Levy Road provide key access to Purau and through to Koukourarata Port Levy. An average of 600 and 300 people use these respective roads each day. Purau Avenue is particularly vulnerable to flooding and rising groundwater because it’s low lying and close to the outlet of Purau Stream.

Camp Bay Road is a low-volume road that provides access to properties on the eastern side of the Purau and through to Camp Bay. During peak holiday seasons, this road has an average daily traffic of about 100 vehicles. The section of Camp Bay Road in Purau Bay is particularly at risk of erosion because it’s close to the beach.

Purau has several community facilities, including:

• The jetty and boat ramp in Purau are valued and well-used community assets, providing one of the only inter-tidal boat-launching facilities in the harbour. Both assets are currently at risk of coastal hazard impacts and will become increasingly impacted as sea levels rise. They have some protection from the rock armouring that protects Purau Avenue. The boat ramp is scheduled for a major upgrade at some point over the next 12 months, which aims to improve its access and resilience. There are no works planned for the jetty which is currently maintained as needed.
• The Purau Recreation Ground, the esplanade reserve – which runs up either side of Purau Stream for a distance – and the strip of foreshore reserve that sits between the beach and road are all at risk from coastal hazards. The recreation ground has a playground and temporary toilet facilities (the original toilet has been closed since the Canterbury Earthquakes), both of which are at risk of coastal hazards. The foreshore reserve is often used for parking and is already experiencing erosion in some places. Over time, rising sea levels will cause greater erosion of the foreshore reserve which will result in increased risk of flooding and ponding at the recreation ground.

Coastal flooding, coastal erosion and rising groundwater all pose a risk to Purau. The images below show that as sea levels rise, the area will experience deeper flood events and the public assets in the area will become more and more at-risk. The floodwater will 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 of 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 is hard to predict the rate at which sea levels are going to rise further in the future. The rate of change will depend on global green house gas emissions and what impact this has on our climate. If different tipping points are reached, it’s possible we will see sea levels rise much more quickly. That is why it is important to have a plan in place for the future of our coastal communities. The following images show how this area will be affected by coastal hazards as sea levels rise, during a 1-in-100-year-storm event. Over this time, the roads will become more and more at-risk.

The road, reserves, jetty and boat ramp are all at risk from current, and future, coastal hazard impacts. If nothing is done, coastal hazards will increasingly cause road interruptions and closures, making access to and through Purau more difficult. The area will become damper as groundwater levels rise and flooding occurs more often, making the reserve areas and public toilet less useable. The shorefront will be eaten away by erosion, impacting the road and access to the beach. The ability to access and use the boat ramp and jetty will also become harder over time.

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 address the risks to one asset will have an impact on how other assets could be affected by coastal hazards and the options we have available to manage those risks. In Purau, the decision to either protect the roads in their current location or move them out of the hazard zone will have a big impact on the other assets. The Coastal Panel has identified two approaches that help to show how these different adaptation options might fit together. These two approaches are as follows.

1. Hold the line

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

Over the long term, holding the line would involve a combination of coastal protection, raising the road, improved drainage, and groundwater pumping. However, over time, the mudflats, beach and foreshore would be lost as sea levels rise and reach the hard edge of the road.

Under this approach, the recreation ground would be given some protection from coastal hazards, but it’s likely it would become boggy and unusable over time. One option would be to build a new, flood-proofed toilet facility on a higher part of the reserve that could be used in the short term and then moved when the reserve becomes too wet to use, access is lost, or when the risk of flooding becomes too great.

Maintaining and improving existing rock armouring along Purau Avenue would also protect access to the jetty and boat ramp. The resilience of these structures could be improved for some time through flood-proofing – which may involve raising the jetty and boat ramp and adding to the existing armouring – or the existing jetty could be replaced with a more resilient one.

2. Work with nature

In time, it may be better to move at-risk sections of road away from the shorefront and out of the hazard zone, creating a new way to access Purau and connect to Purau-Port Levy Road and Camp Bay Road. This option could be used when it becomes harder and more expensive to maintain the road (likely around 10 to 25 years from now), or when actions to protect the road (‘hold the line’) become less effective.

Removing these sections of road would provide space for the mudflats, beach and foreshore to move inland as sea levels rise, meaning they will continue to provide recreational and ecological benefits. We could also encourage the naturalisation of the reserve and recreation ground through the planting of native plants that would provide some defence against coastal hazards and enhance the ecological values in the area.

As mentioned, the recreation ground will become wetter as groundwater levels rise and eventually become too boggy to use. The options for the toilet work under both approaches.

Depending on which sections of road are relocated, it’s possible that access to the wharf and boat ramp might be affected over time. The resilience of these structures could be improved for some time through flood-proofing as described above.

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. 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.

Maintaining the at-risk sections of Purau Avenue, Purau-Port Levy Road and Camp Bay Road is expected to become harder and more expensive over time. The adaptation pathway map below shows that at a certain point – likely around 10 to 25 years from now – changing conditions will mean maintaining the existing roads is no longer worth the increasing costs and disruption. As we near this point, we could look to flood-proof and protect the roads to different levels to buy us a bit more time or a lot more time. Alternatively, we could move the roads straight away, or wait until a point in time when flood-proofing doesn’t work as well, and then move them.

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

The jetty and the boat ramp are both at risk from coastal hazards, although planned upgrades will increase the resilience of the jetty for a time. The structures themselves and the ability to access them will be increasingly impacted by coastal hazards.

The adaptation pathway map below shows that in around 10 to 25 years from now, a decision will need to be made to either flood-proof and protect the existing jetty, or build a new and more resilient jetty in the same location, or close the jetty and/or boat ramp as they become more impacted by coastal hazards.

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

As sea levels rise, we expect the reserve areas will be increasingly impacted by coastal flooding, rising groundwater and coastal erosion.

The adaptation pathway map below helps to show that while the reserves may continue to function in the same way for a time, nature will eventually take its course. This will mean the shorefront reserve is increasingly eroded and the recreation ground will become damper and difficult to use.

The pathway map shows that we could do very little and let this area change naturally over time, or we could take a more active approach and plant and landscape these areas to better support ecological values. This could happen straight away or once the reserves can no longer be used and maintenance becomes too difficult. These decisions are something we want your feedback on because they’ll influence the way the area can be used.

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

Temporary toilet facilities have been in place in Purau since the permanent toilet was damaged in the Canterbury Earthquakes. The toilet is located on the recreation ground which is vulnerable to coastal hazards, particularly coastal flooding and rising groundwater. The adaptation pathway map below shows that a decision needs to be made about whether to build a new, resilient and relocatable toilet facility on the recreation ground, or in a new location further away from the hazards, or whether to remove the toilet altogether.

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