The Waimakariri River is one of the largest rivers in Canterbury, on the eastern coast of New Zealand's South Island. It flows for in a generally southeastward direction from the Southern Alps across the Canterbury Plains to the Pacific Ocean. The river rises on the eastern flanks of the Southern Alps, eight kilometres southwest of Arthur's Pass. For much of its upper reaches, the river is braided, with wide shingle beds. As the river approaches the Canterbury Plains, it passes through a belt of mountains, and is forced into a narrow canyon (the Waimakariri Gorge), before reverting to its braided form for its passage across the plains. It enters the Pacific north of Christchurch, near the town of Kaiapoi. Instead of being unoccupied Crown land as are most New Zealand river beds, the bed of the Waimakariri River is vested in the Canterbury Regional Council (Environment Canterbury). Name The name Waimakariri comes from the Māori words wai, meaning water, and makariri, 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 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