Waimakariri River

The name Waimakariri comes from the Māori words , meaning water, and , meaning cold. The river was briefly renamed as the Courtenay River in 1849 by the chief surveyor of the Canterbury Association, Joseph Thomas, in honour of Lord Courtenay. However, this name quickly fell into disuse in favour of the traditional Māori name. The Waimakariri is colloquially referred to as the 'Waimak', a shortening of the Māori name. ==Geography==

The source of the Waimakariri is located in the Southern Alps, at the head of a valley to the west of Arthur's Pass, where it is primarily fed by snow melt and glacial runoff. The river flows in a southerly direction, before turning east around the base of Mount Stewart. The river at this stage becomes braided, and is joined by the Bealey River as it flows across wide shingle beds. As the river is joined by the Esk River, the Waimakariri river is forced into a narrow series of gorges and ceases being braided. This continues as the river flows through the foothills of the Southern Alps, and its valley is used by the Midland Line railway as part of its traverse of the Southern Alps. The river exits the foothills at the Waimakariri Gorge, at which point it again expands to a braided system. Once on the Canterbury Plains, the Waimakariri flows in a roughly east-south-easterly direction towards the Pacific Ocean. As with other braided river systems, the main channels frequently change within the primary riverbed, especially during periods of high flow rates. Geological evidence indicates that this mobility has extended to the river itself in the past, at times flowing through the current location of Christchurch into what is now the Avon Heathcote Estuary, and in a different era flowing into Lake Ellesmere / Te Waihora, to the south of Banks Peninsula. To protect Christchurch and other settlements near the river, multiple flood protections have been constructed either side of the river since European settlement, dating as early as the Canterbury Rivers Act 1868. The river currently reaches the Pacific Ocean just to the north of Christchurch, entering Pegasus Bay by way of Brooklands Lagoon. The Waimakariri marks one of only a few breaks in the roughly length of Pegasus Bay. Along with two other rivers which enter Pegasus Bay (Ashley River / Rakahuri and Waipara River), the Waimakariri is almost entirely responsible for the sediment which forms the bay and its coastal plain. Waimakariri River Regional Park Environment Canterbury manages a regional park covering including the Waimakariri River bed and land on the river margins, to allow for recreation and conservation activities in addition to flood protection. The first stages of the regional park were opened in 2005. The park is divided into sections with different characteristics, and can support a range of activities including walking, picnicking, trail running, mountain biking, fishing, gamebird hunting and horse riding. ==Ecology==

As one of the largest rivers on the Canterbury plains, the Waimakariri is an important habitat for wildlife, including many endangered species of plants and animals. The dry sections of riverbed are home to black-fronted terns, where braids in the river provide a natural barrier to predators. The river and its tributaries are home to native species, including crayfish / kōura, New Zealand longfin eel, short-finned eel, lamprey and many species of invertebrates. The river is one of the few remaining habitats for the critically endangered Canterbury mudfish (kowaro), which previously inhabited wetlands across the Canterbury plains, while a portion of its riverbank is home to one of only two known remaining populations of Olearia adenocarpa. The salmon population dates to the early 1900s, when they were introduced from California, and results in large salmon runs near the river mouth in summer. ==Development==

In 1923 the river was mainly investigated for a hydroelectric dam to supply electricity to Christchurch. It received support from the community but the dam was never built since the Government offered inexpensive electricity from the Lake Coleridge scheme. The Central Plains Water Trust is proposing to take of water from two points on the Waimakariri River as part of the Central Plains Water enhancement scheme. ==Pollution==

In 2007 the Waimakariri was ranked as one of the ten most polluted of the larger rivers in New Zealand. Some of the pollution was caused by liquid wastes from industries such as a meat processing plant and wool scourers in the vicinity of the river. The wastes were discharged directly into it but as of 2012 it was piped to the municipal sewage treatment plant. There had been some non-compliance issues with the resource consents for water discharge. == Cultural references ==

The Waimakariri River is described in several works by author Ruth France. Her poem "After Flood", published under the pseudonym "Paul Henderson", describes "the alive / Roar of the river loud on the loose", and as being an "age-long wanderer, age-wily". Her novel, Ice Cold River (1961), describes the flooding of a family farm at Christmas after the Waimakariri River bursts through a stopbank:The water advanced so slowly and quietly that it seemed no more than the tide making in an estuary backwater.... [Q]uite suddenly, the lake of water seemed to lift itself, hurled itself over the garden and against the house in a wave that thumped as did a blasting operation at a distance. Immediately the house was surrounded, and the wave went on, eating up the fields with rapid teeth of dirty foam, in which sticks and grass and debris turned over, were engulfed, and reappeared in an endless sucking whirlpool. ==Bridges==

From upstream to downstream, the current bridges are: File:A bridge over Waimakariri River by Waimakariri Falls hut, Arthur's Pass National Park, New Zealand 17.jpg|Waimakariri Falls Bridge File:Bealey Bridge.jpg|Bealey Bridge File:Two DXC class locomotives crossing the Waimakariri River bridge.JPG|Midland Line bridge File:Waimakariri River bridge.jpg|Mount White Bridge File:Waimakariri Gorge Bridge 002.JPG|Waimakariri Gorge Bridge File:Between the bridges 20170422 8637 EOS M-22.jpg|SH1 bridges (looking north) File:Bridge over Waimakariri River, New Zealand 08.jpg|Main North Road bridge File:Bridge over Waimakariri River, New Zealand 02.jpg|Main North Line bridge ==References==