Rakaia River
Encyclopedia
Canterbury Plains
The Canterbury Plains are an area in New Zealand centred to the south of the city of Christchurch in the Canterbury Region. Their northern extremes are at the foot of the Hundalee Hills in the Hurunui District, and in the south they merge into the plains of North Otago beyond the Waitaki...
in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
's South Island
South Island
The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...
. The Rakaia River is one of the largest braided rivers in New Zealand. The Rakaia River has a mean flow of 203 cubic metres per second and a mean annual seven-day low flow of 87 cubic metres per second.
It rises in the Southern Alps
Southern Alps
The Southern Alps is a mountain range extending along much of the length of New Zealand's South Island, reaching its greatest elevations near the island's western side...
, travelling 150 kilometres in a generally easterly or southeasterly direction before entering the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
50 kilometres south of Christchurch
Christchurch
Christchurch is the largest city in the South Island of New Zealand, and the country's second-largest urban area after Auckland. It lies one third of the way down the South Island's east coast, just north of Banks Peninsula which itself, since 2006, lies within the formal limits of...
.
For much of its journey, the river is a braided river
Braided river
A braided river is one of a number of channel types and has a channel that consists of a network of small channels separated by small and often temporary islands called braid bars or, in British usage, aits or eyots. Braided streams occur in rivers with high slope and/or large sediment load...
, running through a wide shingle bed. Close to Mount Hutt, however, it is briefly confined to a narrow canyon known as the Rakaia Gorge
Rakaia Gorge
The Rakaia Gorge is located on the Rakaia River in inland Canterbury in New Zealand's South Island.Like its neighbour, the Waimakariri River, the Rakaia runs through wide shingle beds for much of its length, but is forced through a narrow canyon as it approaches the Canterbury Plains.In the 1870s,...
.
In the 1850s, European settlers named it the Cholmondeley River, but this name lapsed into disuse.
The Rakaia River is bridged in two places. The busiest crossing is at the small town of Rakaia
Rakaia
The town of Rakaia is seated close to the southern banks of the Rakaia River on the Canterbury Plains in New Zealand's South Island, on State Highway 1 and the Main South Line. Immediately north of the township are the country's longest road bridge and longest rail bridge, both of which cross the...
, 20 kilometres from the river mouth, where State Highway 1 and the South Island Main Trunk Railway
South Island Main Trunk Railway
The Main North Line between Picton and Christchurch and the Main South Line between Lyttelton and Invercargill, running down the east coast of the South Island of New Zealand, are sometimes together referred to as the South Island Main Trunk Railway...
cross the river using separate bridges. These two bridges are New Zealand's longest road and rail bridges respectively, approximately 1.75 km long. A second bridge, much shorter and less used, spans the Rakaia Gorge.
The Rakaia River is a celebrated Chinook salmon
Chinook salmon
The Chinook salmon, Oncorhynchus tshawytscha, is the largest species in the pacific salmon family. Other commonly used names for the species include King salmon, Quinnat salmon, Spring salmon and Tyee salmon...
(Oncorhynchus tshawytscha) fishery. The Rakaia is known for its large wrybill
Wrybill
The Wrybill or Ngutuparore Anarhynchus frontalis is a species of plover endemic to New Zealand. It is unique in that it is the only species of bird in the world with a beak that is bent sideways ....
population which represents 73 percent of the total population. Other important bird species known to be found in the Rakaia riverbed are Wrybill, Black fronted Tern and Banded Dotterel.
The Central Plains Water
Central Plains Water
Central Plains Water, or, more fully, the Central Plains Water Enhancement Scheme, is a large-scale proposal for water diversion, damming, reticulation and irrigation for the Central Plains of Canterbury, New Zealand....
Trust is proposing to take up to 40 cubic metres per second of water from the Rakaia River as part of the Central Plains Water
Central Plains Water
Central Plains Water, or, more fully, the Central Plains Water Enhancement Scheme, is a large-scale proposal for water diversion, damming, reticulation and irrigation for the Central Plains of Canterbury, New Zealand....
enhancement scheme.