As River

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As River
Asrivier naby Saulspoortdam, Bethlehem, Vrystaat.jpg
South Africa relief location map.svg
Red pog.svg
Location
Country South Africa
Province Free State
Physical characteristics
Source 
  coordinates 28°30′38″S28°21′47″E / 28.51056°S 28.36306°E / -28.51056; 28.36306
  elevation2,160 m (7,090 ft)
Mouth  
  coordinates
28°16′36″S28°22′22″E / 28.27667°S 28.37278°E / -28.27667; 28.37278 Coordinates: 28°16′36″S28°22′22″E / 28.27667°S 28.37278°E / -28.27667; 28.37278
  elevation
1,630 m (5,350 ft)
Length50 km (31 mi)
Discharge 
  average18 m3/s (640 cu ft/s)

The As River is a tributary of the Liebenbergsvlei River in the eastern Free State, South Africa. Since 1968 it is impounded by the Sol Plaatje Dam (formerly: Saulspoort Dam) at its confluence with the latter river, just east of Bethlehem. Its origin is some 35 km southeast of Bethlehem, on the northern slopes of the Rooiberge, near Clarens. With the opening of the northern delivery tunnel of the Lesotho Highlands Water Project in 1998, the once tiny stream was transformed to a strong-flowing river. [1]

Free State (province) Province of South Africa

The Free State is a province of South Africa. Its capital is Bloemfontein, which is also South Africa's judicial capital. Its historical origins lie in the Boer republic called Orange Free State and later Orange Free State Province.

South Africa Republic in the southernmost part of Africa

South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by 2,798 kilometres (1,739 mi) of coastline of Southern Africa stretching along the South Atlantic and Indian Oceans; to the north by the neighbouring countries of Namibia, Botswana, and Zimbabwe; and to the east and northeast by Mozambique and Eswatini (Swaziland); and it surrounds the enclaved country of Lesotho. South Africa is the largest country in Southern Africa and the 25th-largest country in the world by land area and, with over 57 million people, is the world's 24th-most populous nation. It is the southernmost country on the mainland of the Old World or the Eastern Hemisphere. About 80 percent of South Africans are of Bantu ancestry, divided among a variety of ethnic groups speaking different African languages, nine of which have official status. The remaining population consists of Africa's largest communities of European, Asian (Indian), and multiracial (Coloured) ancestry.

Sol Plaatje Dam dam in Free State, South Africa

Sol Plaatje Dam is an earth-fill type dam located at the confluence of the As and Liebenbergsvlei Rivers near Bethlehem, Free State, South Africa. It was established in 1968 and serves mainly for municipal and domestic water supply. The hazard potential of the dam has been ranked high. The reservoir receives water from the Lesotho Highlands Water Project via the As River.

Contents

Water delivery

The As River Outfall of the Lesotho Highlands Water Project, situated 9 km north of Clarens, was opened in 1998. Asrivieruitval, noord van Clarens, b.jpg
The As River Outfall of the Lesotho Highlands Water Project, situated 9 km north of Clarens, was opened in 1998.

The As River is one of the discharge points for the Lesotho Highlands Water Project. [2] As of 2004, 18 cubic meters of water was released per second, [1] and the river's flow is consequently not seasonally variable. [3]

The Stortemelk Dam, situated downstream of the outfall, was one measure taken by the then Department of Water Affairs, to stabilize water flow and limit erosion. [3] By 2004, four weirs had been built. [1]

Power generation

Two privately owned hydro powered power plants, the Sol Plaatje and Merino, were commissioned in 2009 and 2012 respectively, and supply a total of 7 MW to the power grid. [4] The automated and low maintenance Stortemelk Hydropower Project at the Botterkloof Dam is set to contribute a further 4.4 MW to the power grid, starting July 2016. [3] [5]

Bethlehem Hydro owns and operates two small hydro power plants situated in the Dihlabeng Local Municipality in the Free State province of South Africa. The scheme utilizes the water supplied to South Africa by the Lesotho Highlands Water Project, which releases water into the As River via a tunnel outlet near the town of Clarens. South Africa has limited potential for hydro energy due to low average annual rainfall making projects like Bethlehem Hydro rare. The project was identified in 1999 and developed by NuPlanet Project Development. The two power stations in the scheme will cut back carbon dioxide emissions by 33,000 tons per year by reducing the demand for traditional fossil-fuel power stations.

The watt is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per second, and is used to quantify the rate of energy transfer. In dimensional analysis, power is described by .

Ecological impact

The opening of the northern delivery tunnel in 1998 caused physical and chemical changes to the river, as water volumes increased and water temperature decreased, scouring of the river channel occurred, and much silt was deposited in Saulspoort Dam. [1] Populations of key indicator species like smallmouth and largemouth yellowfish decreased, and seven of the river's nine fish species disappeared from the outfall's vicinity. Recovery of invertebrates was only noticeable some kilometers downstream, and the weirs proved ineffective when water is released in high volumes. Though much habitat is still available, the river's population by aquatic organisms is limited by water turbidity, low water temperature and its erosion potential. [1]

Smallmouth yellowfish species of fish

The smallmouth yellowfish is a species of ray-finned fish in the genus Labeobarbus. It has become an invasive species in rivers of the Eastern Cape, South Africa, such as the Mbhashe River.

Largemouth yellowfish species of Actinopterygii

The largemouth yellowfish or Vaal-Orange largemouth yellowfish is a ray-finned fish species in the family Cyprinidae. This large freshwater barb is found in southern Africa.

Etymology

The name is often mistranslated from Afrikaans to English as "Ash River". The name, however, refers to a wagon axle which, according to legend, broke near the river (the Afrikaans word for an axle being “as”); therefore a correct translation would be "Axle River", and not “Ash River".

Afrikaans West Germanic language spoken in South Africa and Namibia

Afrikaans is a West Germanic language spoken in South Africa, Namibia and, to a lesser extent, Botswana and Zimbabwe. It evolved from the Dutch vernacular of Holland spoken by the largely Dutch settlers in the south-west of what is now South Africa, where it gradually began to develop distinguishing characteristics in the course of the 18th century. Hence, it is a daughter language of Dutch.

Ox-wagon

An ox-wagon or bullock wagon is a four-wheeled vehicle pulled by oxen. It was a traditional form of transport, especially in Southern Africa but also in New Zealand and Australia. Ox-wagons were also used in the United States. The first recorded use of an ox-wagon was around 1670, but they continue to be used in some areas up to modern times.

See also

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References

  1. 1 2 3 4 5 Van Wyk, Francois; du Preez, Hein (2004). The environmental impact of releases from Katse Dam on the Ash and Liebenbergsvlei Rivers (PDF). WISA 2004 biennial conference and exhibition of the Water Institute of Southern Africa: Water Institute of Southern Africa. pp. 304–208. ISBN   1-920-01728-3. Archived from the original (PDF) on 24 September 2015. Retrieved 23 August 2015.
  2. "The story of Katse dam". The Highlands Journey - Lesotho. golesotho.co.za. Archived from the original on 15 February 2015. Retrieved 23 August 2015.
  3. 1 2 3 Wilkins, Blake (February 2015). "Unique contract does it for hydro delivery". Brooke Pattrick Publications. pp. 20–21. Archived from the original on 10 May 2017. Retrieved 21 August 2015.
  4. "Introduction". Bethlehem Hydro. Archived from the original on 20 October 2015. Retrieved 21 August 2015.
  5. "Stortemelk Hydropower Project, South Africa". Aurecon Projects. Retrieved 21 August 2015.