South Dunedin needs to adapt so we can cope with climate change and look after our people, property and places.
What adaption means
Adaptation is not a new idea. It means making changes in response to hazards and risks. It’s also a chance to make our homes better and our communities stronger.
South Dunedin is home to about 13,500 people and 1,500 businesses. An adaptation plan helps us ensure these people and businesses have a good future and we can do some great things for the area.
We don’t know what it will look like yet - we could build new infrastructure to reduce flooding, create housing in lower-risk areas, restore natural wetlands to absorb the water and create more green space for recreation and wildlife. There are a lot of options.
The history of South Dunedin
South Dunedin has always adapted and always will. Modern-day South Dunedin is built on what was once a coastal wetland, similar to Hoopers and Papanui Inlets on Otago Peninsula. Like most wetland areas, it was full of birds and fish and, historically, provided Māori with abundant mahika kai (food gathering) resources and a place to moor their canoes while on eel fishing trips to the Taieri. (From Thematic Māori Heritage Study of Dunedin, 2016 by Tahu Potiki and KTKO).
The low-lying South Dunedin area now known as ‘The Flat’ was marshy and covered with silver tussock, rushes and flax. Along the harbour margin there was a wide, tidal mud-flat, and there were coastal lagoons and wide, low sand dunes, much flatter than those along the St Clair – St Kilda coast today.
The reclamation
The influx of European settlers to Dunedin in the mid-1800s created huge demand for dry, flat land, so the settlers set about reclaiming the area, draining it and filling it in with sand and rock.
Reclamation continued for many years and was not officially completed until 1978 with the opening of Portsmouth Drive.
The mixture of sand and silt reclaimed from the harbour still lies under South Dunedin. It absorbs rainwater and runoff like a sponge and transports this water towards the sea.
This underground water – the groundwater table – in some places sits less than half a metre from the ground surface and rises and falls with tides and seasons.
This makes South Dunedin vulnerable to climate change in climate and heavy rainfall events, storms, and rising sea level.
What we’re doing about the water
We expect to spend $37 million over 10 years (2021-2031) to reduce flood risk in South Dunedin. There’s a long list but we’ve already achieved quite a bit - some things you can see and some things you can’t.
We’ve installed filters, monitors and alarms, reinforced aqueducts, and we now clean the mud tanks more often. We’ve also fitted valves, replaced pipes, changed building codes, upgraded systems, hired dedicated staff, and strengthened our emergency procedures around what happens before and during a big storm.
What else we’ll do to reduce flood risk
- Get new higher-flow mud tanks, pump stations or new ways of diverting and managing water
- Monitor flows in our water and wastewater networks and improve the accuracy of our computer hydraulic models
- Inspect the stormwater pump stations (Portobello Road and Tainui) to see how we can improve them.
We’ve made a Coastal Plan
An important part of South Dunedin’s future will be managing the impact of climate change on the coast.
Between waves, winds, tides, currents and storm surges, the St Clair to St Kilda coast is exposed to a lot of natural forces. These forces erode the beach and dunes and cause damage to the infrastructure.
We know that climate change is speeding up the rate of damage - and rapid changes to the coastline spell trouble for the rest of the area - because the dunes and sea wall help keep the ocean out of South Dunedin.
The St Clair – St Kilda Coastal Plan is one of the related projects that will contribute to South Dunedin Future. The plan lays out how we will manage and adapt this coast to handle the effects of coastal hazards and climate change.
We’ll do a range of work over the coming months and years and keep you updated as we go.
- Investigate the Kettle Park landfill
- Implement a monitoring programme for the coast
- Improve beach access at St Clair.