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 neighbouring saltmarsh, found at the head of Whakaraupō in Teddington, hold significant conservation value. Saltmarsh ecosystems are nationally rare and threatened because humans have changed many of the natural environments they exist in.

Despite being affected by farming activities and divided by a road, Teddington supports the largest and most diverse area of saltmarsh vegetation in the Waitaha Canterbury region. The saltmarsh turf is a unique mix of salt-tolerant native plant species which change into taller sea-rush and saltmarsh ribbonwood further inland. In this habitat you can find maakoako/sea primrose and the northernmost population of coastal wind grass, both of which are at risk of extinction, adding to the ecological importance of the area.

The mudflats offer necessary habitat for a range of seabirds, including the second-largest flocks of bar-tailed godwits and South Island pied oystercatchers, making them of national importance. The mudflats also make up the largest area of inter-tidal habitat in the region.

The area has a rich cultural past and is important to mana whenua as a place of mahinga kai. Once a site for the catching and drying of shark, it supports a wide range of plant and animal species unique to New Zealand and even to the area.

There are three key roads in Teddington that provide access to communities further around Whakaraupō and into

Koukourarata: Governors Bay-Teddington Road, Gebbies Pass Road, and Charteris Bay Road.

Both Governors Bay-Teddington and Gebbies Pass roads are considered minor arterial roads because of the important role they play in providing access to communities across the harbour. These roads are used by around 2,000 and 900 vehicles respectively each day.

Charteris Bay Road is a collector road used by around 2,000 vehicles each day. Between 6 and 9 per cent of this traffic is heavy vehicles. It’s not uncommon during storms for water to pond around these roads, particularly at the Gebbies Pass intersection. Flooding also happens when storms arrive at the same time as spring/king tides. Despite this, there have only been a handful of recorded closures of these roads in the Teddington area over the past decade.

Rising groundwater and coastal flooding pose the biggest risks to Teddington and the public roads in the area. The images below show that as sea levels rise, the area will experience deeper flood events and the roads will become more and more vulnerable. 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. The area affected by these hazards is unlikely to change much due to the shape of the surrounding land, which is steep, but the impacts will become more common and extreme 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.

Maintaining the roads in their current state is expected to become much harder and more expensive over time. In around 25 to 40 years, the mounting maintenance costs and impacts of coastal hazards on access will mean we need to make a change.

You’ve told us how important you think it is to keep vehicle access around the coast, to make sure you have access between the city and your homes over the long term. The importance of this is reflected in the community objective about infrastructure.

With all of this in mind, the Coastal Panel has considered all workable adaptation options and, in agreement with expert advice from the Specialist and Technical Advisory Group, is proposing two possible ways to address the risks to the roads as sea levels rise. These two options are:

1. Flood-proof the roads

This option could be used to address coastal-hazard risks over the next 100 years. Flood-proofing the road could happen in a number of different ways, including raising the surface of the road above future flood levels, using more flood-resilient materials, and/or installing more culverts to help with drainage.

Some of the low-lying sections of road near the coast and streams may also need to be reinforced with things like rock armouring to protect them against erosion and to make sure any flood-proofing would work.

There are opportunities and other things we need to consider for any option. Here are some for flood-proofing:

At this early stage in the process, we don’t have enough information to understand exactly what the cost of flood-proofing and raising the road would be. Our best estimate at this point in time is anywhere between $15 million to $50 million to raise the road between 40 centimetres and one metre.

2. Move the road to higher ground

We could move the at-risk sections of Governors Bay–Teddington Road and Charteris Bay Road to connect with Gebbies Pass Road further inland. This would create a new road in a place with no risk of coastal hazards.

By removing the existing road, we could change the way the land is used, allowing native plants to grow back where the old road used to be. Another option could be to close the existing road or maintain it to a lower standard once the new road was built. It could be used for recreation or as a back-up road for a while, until this was no longer workable.

To build the new road, 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.

It’s also important to remember there are several other sections of road at risk to coastal hazards in Whakaraupō and Koukourarata. Moving the road in Teddington would only solve part of the problem.

Here are some opportunities and things we’d need to consider for moving the road:

At this early stage in the process we don’t have enough information to understand exactly what the cost of moving the road would be. Our best estimate at this point in time is about $170 million to move all at-risk sections of road.

he adaptation pathway map below helps to show the options we’ve talked about and how they could work over time. It shows that at a certain point – likely around 25 to 40 years from now – changing conditions will mean maintaining the existing road is no longer worth the increasing costs and disruption. As we near this point, we could look to flood-proof the road to different levels to either buy us a bit more time or a lot more time.

Alternatively, we could move the road straight away, or wait until a point in time when flood-proofing wasn’t working as well, and then move it. If and how we combine these two options is something we want your feedback on.

Acting at the right time is an important part of a pathway. For example, it’s hard to predict when it will become too costly and disruptive to keep repairing the road, and it’s likely some parts will have issues before others. To get around this uncertainty, we’ll make the decision to move from one option to another based on signals and triggers. In other words, we’ll act when we start to see changes in conditions. The Coastal Panel will be thinking about what these signals and triggers might look like in more detail.