Fast-tracking of Canterbury flood protection a critical first step in climate adaptation

More than $24 million will be spent on a programme of flood protection projects in Canterbury thanks to central government’s climate resilience fund.

In December, Environment Canterbury confirmed $15.5 million in funding from the Ministry of Business Innovation and Employment’s Provincial Development Unit (PDU) towards a combined project value of $24.2 million in a co-funding arrangement.

Through this programme, the PDU will contribute 64 per cent of the cost of each project as a grant. The remaining 36 per cent will be co-funded by Environment Canterbury through a combination of contributions from partners, operational funding and rates.

The programme has a strong dual purpose of supporting the Canterbury COVID recovery by generating employment for local contractors and workers to boost the regional economy, as well as providing climate change resilience and transformational opportunities for communities across the region. All projects must be completed by 31 December 2023.

Managing the region’s flood protection assets

Environment Canterbury manages 59 river control and drainage schemes from Kaikōura to Waitaki, with a total asset value of $673 million, higher than any other region in New Zealand. These schemes help communities build resilience to flood events providing safety and security to productive land and protecting families, businesses and critical infrastructure.

Chief Executive Stefanie Rixecker said the grants were a welcome boost to strategic projects that will benefit Cantabrians for years to come.

“Flood protection projects are worthy public investments offering a high degree of return given the significant community assets they protect. We welcome the opportunities that co-investing with central government offers, from the boost to our region’s economy to kick-starting projects that would have otherwise taken decades to fund through our current rating districts.”

Taking action to adapt for climate change 

Chief Operating Officer Nadeine Dommisse said climate change was a major factor that must be integrated across all aspects of Environment Canterbury’s operational decision-making.

Flooding is the most common natural hazard we all face in New Zealand. As the world confronts a changing climate, we can expect the extent of flooding to be affected through a range of mechanisms including rainfall, temperature, sea-level and river channel changes.”

“With the expectation of more frequent and intense climate change-induced flood events, we need to review how our river management and flood protection schemes operate. Increased funding will improve flood protection as a critical ‘first step’ in climate change adaptation action which will help us build a more resilient community in the Canterbury region.”

Achieving environmental outcomes 

Councillor John Sunckell said Environment Canterbury now has a rare transformational opportunity particularly with respect to supporting the unique character of our braided rivers.

“We have to take a holistic approach to the health and vitality of the river. By engaging with communities and partnering with mana whenua and other stakeholder groups we can accelerate regeneration of the natural environment and lead climate change resilience for the Canterbury region.”

“These initiatives strongly support our Environment Canterbury Strategic Direction 2018-2021 (PDF File, 399.02KB), enable a rapid start of valuable Braided River Revival/ Whakahaumanu Ngā Awa ā Pākihi works and will be a significant catalyst of positive change for current and future generations,” he said.

These are the six funded projects in Canterbury:

1. Regionwide planting and berm transition
  • Investment: about $10 million

Planting trees in and around river margins is essential for flood resilience and protection of environmental values. River berms and margins are the strip of land directly adjacent to the active part of the riverbed. Planting in these areas provides a buffer which slows floodwaters and prevents bank erosion.

The margins of braided rivers are critical to their function and form and are rich in environmental values. Many are currently choked with weed growth which is likely to accelerate with climate change.

This natural infrastructure project generates multiple benefits in addition to flood protection, such as greater biodiversity, weed control, enhancements to wetlands and mahinga kai as well as opportunities to establish recreational areas.

Approximately 20 rivers across the region will benefit from this project.

2. Rangitata 2019 flood recovery
  • Investment: about $8.5 million

A major flood event in December 2019 affected several alpine rivers in Canterbury. The Rangitata River broke out of the main channel at three key locations, causing a significant amount of damage to flood protection, roading, rail, farm, electricity supply and other assets.

New flood protection and erosion control infrastructure and tree planting is required to protect communities and critical lifelines such as road, rail and communication networks.

A number of investigations are planned for the river as well as a substantive natural infrastructure programme focusing on planting, weed control, wetland enhancement and mahinga kai enhancement opportunities.

3. Waimakariri River flood protection at McIntoshs Bend
  • Investment: about $3.2 million

The Waimakariri and Kaiapoi River stopbanks protect Kaiapoi township and the surrounding area from flooding.

They are part of the Waimakariri-Eyre-Cust flood protection system which is maintained by Environment Canterbury.

In the 1960s, riverbank rock armour was installed to prevent erosion and stopbank breach on this very sharp bend.

Over the years the river has narrowed, and a deep scour hole has developed, increasing erosion vulnerability.

The new rock works will strengthen existing rock protection around McIntoshs Bend and add new rock protection along the lower Kaiapoi River and adjacent stopbank.

4. Ashley River/Rakahuri protection and fairway management
  • Investment: about $1 million

The Ashley River/Rakahuri is a key feature of the North Canterbury landscape that poses a significant flood risk to the communities living on its floodplain.

This project involves removing exotic vegetation which is currently choking a 21 kilometre section of the river between Ashley Gorge and the Okuku River confluence, and in the Okuku River.

Braided Rivers are an iconic and precious feature of the Canterbury environment.

As a result of the introduction and invasion of weeds, predators, and human activities, braided rivers and their bird species, plants, native fish and insects are under threat.

Under the umbrella of Braided River Revival / Whakahaumanu Ngā Awa ā Pākihi Environment Canterbury is prioritising the restoration of our rivers normal braided character, which will in turn will enhance a range of natural biodiversity values including natural braided river habitats,

5. Halswell/Huritini weed barrier replacement
  • Investment: about $1 million

This project involves the replacement of a piece of critical infrastructure, currently at the end of its life, which is used to capture river weed cut in the Halswell/Huritini River.

Weed is cut from the riverbed in order to manage water levels (both ground and surface water) in the Halswell/Huritini catchment.

Cut river weed must be prevented from entering Te Waihora /Lake Ellesmere, which is a nationally important wetland of huge cultural importance.

If weed were to enter the lake it would severely degrade water quality through release of stored nutrients during decomposition.

6. Waiau township stopbank
  • Investment: about $500,000

The existing banks leave the township vulnerable to breaching in floods from either the Waiau Uwha or Mason Rivers.

Through the upgrade and linking of existing banks, vegetation removal and planting, these works will improve the resilience of the Waiau community to flood events which are predicted to become more frequent and of greater magnitude with climate change.