Braided rivers – Canterbury's iconic treasures

Canterbury’s iconic braided rivers are among some of the most unique in the world – you’d need to travel to the Himalayas or Alaska to find a comparable example.

Our seven alpine braided rivers – the Waiau Toa/Clarence, Waiau Uwha, Hurunui, Waimakariri, Rakaia, Rangitata and Waitaki – contribute 88 percent of surface water flow in the region.

Braided rivers are unique due to their shifting channels and banks, varying flows, ability to move over the landscape, and ecosystems. Because of this, they provide an outstanding habitat for many rare birds, fish, plants and other species.

The movement of gravels, working and reworking of sediments to form islands, plains, river mouths and coastal beaches, all contribute to sustaining the mauri (life force) of braided river systems.

Over time, and with historical use and development, some of the ecological and biodiversity values of these special rivers have deteriorated.

Canterbury’s braided rivers also provide much of the water to precious groundwater aquifers. Originating in the Southern Alps, these river systems cross the porous soils of the Canterbury Plains, losing water to ground and feeding aquifers deep under the land.

Aquifers provide our fresh drinking water and the vast amounts of water needed to sustain our population and our economy, while surface water is still king when it comes to irrigation.

Long before braided rivers were kāinga mahinga kai/food gathering habitat for Māori, a water supply for farmers and a recreational hotspot for the half-million people living nearby, they were quite literally world builders.

For thousands of years, mighty ice-age glaciers carved through the Southern Alps, pulling loose rock and sediment from headwaters and sending them forth in a great alluvial wash from the mountains to the sea.

Loads were deposited in such quantities that the coastline was driven east and New Zealand’s largest area of flat land, the Canterbury Plains, was created.

Biodiversity and ecology

Braided rivers provide an abundant supply of food and habitat for many native and precious species. Nesting for about 25 species of native birds can be found, the majority of which are threatened and face increased pressures as the character of the rivers constantly change.

Notable species in our braided rivers includes black-fronted tern/tarapirohe; wrybill/ngutu pare; black-billed gull/tarāpuka; lamprey/kanakana; tuna/eel; whitebait/inanga; salmon/hāmana; and trout/tarauta.

The biologically rich rivers are one of the last remaining strongholds of biodiversity in Canterbury.

Flora and fauna in and amongst the rivers live a precarious existence, because of constant threats of habitat loss through weed growth, flooding, and human interference such as land development.

A wrybill chick, newly hatched

However, low flow can be as bad as flooding for natives. Low flow allows predators like cats, stoats and hedgehogs to reach nesting birds and their chicks which are otherwise protected.

Especially susceptible to these dangers include already threatened species, the wrybill/ngutu pare; black-fronted tern/tarapirohe; and black-billed gull/tarāpuka.

What can I do to help protect these species?

Environment Canterbury principal biodiversity advisor, Dr Frances Schmechel, said we all have a role to play in sharing the environment and protecting these precious rare birds.

“During the breeding season from September to the end of January, keep your dogs on a leash, as chicks can be swallowed before owners have a chance to call the dog back,” Frances said.

“Birds are hard to spot, but if you do see them, give them plenty of space. If they appear agitated, start flying, dive-bomb or hover over you, you’re much too close and may even be standing on their nest.

“Stay on formed tracks and observe signs – many nests with eggs or chicks have been crushed by vehicles because of their camouflage from aerial predators,” she said.

Giving threatened species a helping hand

In 2018-19 Environment Canterbury began black-backed gull/karoro control on several braided rivers. Black-backed gull once co-existed with other endemic braided river birds, but in much lower numbers than are present today.

Numbers have increased markedly recently and there are now large colonies on braided river beds, crowding out other species and creating E. coli problems in the rivers.

In contrast, Frances said, populations of black-fronted tern, banded dotterel, wrybill and black-billed gull have declined in that time, in part due to predation by the larger black-backed gulls.

Black-fronted tern | tarapirohe

“Karoro (black-backed gull) can harass colonies of threatened native birds until the entire colony fails. They can swoop in and devour small chicks whole in just seconds,” she said.

In addition to black-backed gull, pest control operations are carried out for a range of pests including hedgehogs, wild cats, stoats, weasels, ferrets and rats.

“This control, which is mostly trapping, is carried out by community groups and contractors on various rivers. Without it, our precious braided river birds would have even less chance of breeding successfully,” Frances said.

Cultural importance

Tangata whenua have a particular interest in the beds of lakes and rivers, as well as their margins. These are significant for mahinga kai and for the presence of significant sites such as wāhi tapu (sacred place).

The practice of kaitiakitanga/guardianship applies to the ecological health of all waterways. The culture of Ngāi Tahu was developed over hundreds of years alongside the region’s once plentiful, unspoilt waterways.

Braided rivers are part of Ngāi Tahu whakapapa, part of who they are, and are of paramount importance.

Braided river mouths are particularly important for Ngāi Tahu, providing an important habitat for many species.

They are also important in the coastal gravel nourishment process. The beds and margins of lakes and rivers are part of the waterbody, and not separate from it.

Environment Canterbury Tangata Whenua facilitator, Irai Weepu, said this concept is captured in the phrase ‘ki uta ki tai’ (from the mountains to the sea), the holistic view of the catchment as one system.

“This is also integrated with kaitiakitanga from Ngāi Tahu which applies to the ecological health and overall wellbeing of all waterways,” Irai said.

Environment Canterbury's Makarini Rupene with a tuna | eel

Tuna/eels and inanga/whitebait are taonga species for Ngāi Tahu because of their importance in mahinga kai/food and resource gathering.

Healthy waterway challenges

But for the past 120 years, the relationship between Māori and braided rivers has not been a happy one due to the declining number of healthy waterways.

“In the past, every part of the river was pristine and drinkable, every part was abundant with life. Native plants and animals could be sustainably harvested,” Irai said.

“Rivers were full of water and free to flow their natural paths. Now the water is polluted and not always drinkable, and sometimes not swimmable.

“Biodiversity has decreased and plants and animals are most often either absent or too polluted to be harvested. The rivers in some parts are almost empty of water and constrained. The future is getting back what was lost,” he said.

Food from the rivers, particularly tuna and inanga, were lifelines which have gradually been cut-off by land conversion and mistreatment over a number of generations.

Where does Environment Canterbury fit in?

Environment Canterbury is not only legally responsible for managing and protecting braided rivers, but it is also accountable for maintaining and developing three regional parks.

Our regional parks can be found on the shores of Lake Tekapo and the banks of the Waimakariri and Ashley Rakahuri Rivers.

The Regional Council has developed them to be utilised all year round for walking, swimming, picnicking, boating, fishing, gamebird hunting, motocross, mountain biking, bird watching, horse riding and more.

Mountain bikers at Waimakariri Regional Park

The Council’s legal requirements

Environment Canterbury has a clear legal responsibility to manage and protect braided rivers under the Resource Management Act (RMA). Riverbeds, in particular, have a high protection status.

The Canterbury Water Management Strategy (CWMS), implemented by Environment Canterbury with community input, lays out how the region’s water should be looked after and provides a framework to help manage the demands on this precious resource.

Contractors maintaining a stopbank at West Melton Forest

Environment Canterbury manages the lower reaches of rivers to protect communities from flooding.

Our staff and contractors manage and maintain $673 million worth of flood protection, land drainage and erosion control infrastructure including stopbanks, vegetation, drains and rock scour protection.

Works range from construction and maintenance of stopbanks to vegetation management in active channels. By doing so we enhance and protect habitat for vulnerable braided river birds.

Taking action to preserve water quality and quantity

A 2015 Environment Canterbury report showed that between 1990 and 2012 nearly 12,000 hectares of forested river margin land was converted to intensive agricultural use.

This led to increasing public concern over land use around braided rivers and to the formation of the Braided River Action Group (BRAG). It brings together representatives from Environment Canterbury, Te Rūnanga o Ngāi Tahu, Department of Conservation, Land Information New Zealand (LINZ), Federated Farmers, Forest & Bird, and Canterbury’s territorial authorities.

BRAG's purpose is to maintain the character of Canterbury’s braided rivers; consider innovative and regulatory opportunities to improve land management; and prioritise and implement those changes consistently across braided rivers.

Strict rules are now in place to ensure farmers measure and manage the effects of their farming on local water quality. Controls have been placed on land-use activities that could threaten water quality.

In Canterbury we have some of the strictest farming rules in the country. Farmers must operate within limits and adhere to industry-agreed Good Management Practices (GMPs).

The goal is to halt the decline of braided rivers, focusing on goals and targets in integration of water and land management, including protecting biodiversity and water quality.

Shovel-ready projects get $15m boost

Canterbury will benefit from $15.5 million in Central Government funding for flood protection, keeping communities safer and boosting the region’s economy.

The funding is part of the shovel-ready climate resilience and flood protection projects programme delivered through funds set aside by Government in the 2020 Budget.

The six projects that will be funded are:

  • Waiau Township – stopbank repairs and upgrades
  • Ashley | Rakahuri – river protection and fairway management
  • Waimakariri River – Kaiapoi community flood protection
  • Halswell | Hurutini – weed barrier replacement
  • Rangitata River – flood recovery
  • Region-wide planting and berm management project.
Rangitata River in flood, December 2019

Much-needed relief from COVID-19

Deputy Prime Minister Winston Peters announced recently that the funding would help to stimulate regional economies and get people into work.

"There is no doubt climate change poses a real danger to our regions through extreme weather events, coastal inundation, and the associated problems such as erosion, flooding and the destruction of infrastructure,” he said.

“This has a negative impact on regional economies and their productivity. It is imperative that we are providing our regions with the resources they need to protect against these issues.”

Environment Canterbury river engineering manager, Leigh Griffiths, was delighted by the announcement and was excited to be able to progress the six projects.

“Improving flood protection is a critical ‘first step’ climate change adaptation action. This is a great example of where co-investment can truly benefit local communities and provide for current inhabitants and future generations for years to come," she said.

Benefits from this funding

Environment Canterbury Councillor, John Sunckell, said the funding aids the important Canterbury braided rivers, the need to protect them, and those who live near them.

“Five of the projects are on Canterbury’s braided rivers, which are taonga and highly valued by Ngāi Tahu. They are stunning landscapes, with high natural and cultural values," he said.

"This funding allows us to simultaneously care for braided rivers as the special places they are, while keeping our community safe with key infrastructure projects.”

Find out more about our precious braided rivers and the role Environment Canterbury plays in their protection and enhancement.