Selwyn River / Waikirikiri

The Selwyn River / Waikirikiri flows through the Selwyn District of Canterbury in the South Island of New Zealand.[1]

Selwyn River
Location of the mouth within New Zealand
Location
CountryNew Zealand
Physical characteristics
Source 
 • locationSouthern Alps
Mouth 
 • location
Lake Ellesmere / Te Waihora
Length80 km (50 mi)

Description

The river has its source in the Southern Alps and flows east for 80 kilometres (50 mi) before emptying into Lake Ellesmere / Te Waihora, south of Banks Peninsula. Terrace cliffs above the river's upper reaches gave the town of Whitecliffs its name.

For much of its course the river flows through wide shingle channels. In drought years, the river can disappear beneath this bed and seem to dry up completely. This frequently occurs where State Highway 1 crosses the river at the settlement of Selwyn, about 20 kilometres (12 mi) upstream from its outflow into Lake Ellesmere.

In the foothills, the Selwyn flows year-round. On the plains, the riverbed is highly permeable, and the river overlays a deep and porous aquifer. As soon as the river reaches the plains, water begins leaking down through the bed and into the aquifer. In most months, all river-water disappears within 5 kilometres (3 mi) of leaving the foothills. The next 35 kilometres (22 mi) of the river remains dry for most of the year, apart from a small section around the confluence with the permanently flowing Hororata River. About 15 kilometres (9 mi) upstream from Lake Ellesmere shallow groundwater rises back to the surface, and the Selwyn becomes permanent again.

Ecology

Disappearing river flows have significant ecological effects: when the river’s surface water disappears, so does the habitat for many aquatic plants and animals. In response to loss of surface water, aquatic invertebrates and fish must disperse, seek refuge in remnant aquatic habitats, or die. Aquatic plants, algae, and bacteria must form resting stages or die. The dry central reaches of the Selwyn River also constitute a significant barrier for dispersal of invertebrates and for fish migrating between Lake Ellesmere and the headwaters.[2]

Naming

The Selwyn River and its gorge were named in 1849 by the chief surveyor of the Canterbury Association, Joseph Thomas, for Bishop Selwyn. The name was later adopted for the township, the district, and an electorate.[3]

The New Zealand Ministry for Culture and Heritage gives a translation of "gravelly stream" for Waikirikiri.[4]

gollark: They seem to at least work for patent trolls.
gollark: If you don't, you MAY be lawsuited.
gollark: What muons? You haven't been converted yet.
gollark: Subject to conservation laws.
gollark: If you don't use Us when needed, you may be converted into muons at random or deterministically at our discretion.

References
  1. "Place name detail: Selwyn River/Waikirikiri". New Zealand Gazetteer. Land Information New Zealand. Retrieved 5 April 2008.
  2. Mike Scarsbrook; Scott Larned; Graham Fenwick; Dave Kelly. "Biodiversity in a disappearing river". NIWA. Archived from the original on 23 February 2013. Retrieved 22 March 2013.
  3. Reed, A. W. (2010). Peter Dowling (ed.). Place Names of New Zealand. Rosedale, North Shore: Raupo. p. 362. ISBN 9780143204107.
  4. "1000 Māori place names". New Zealand Ministry for Culture and Heritage. 6 August 2019.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.