Orange–Fish River Tunnel
Encyclopedia
The Orange–Fish River Tunnel is an 82.8 km irrigation tunnel
in South Africa
which diverts water from the Orange River
under the Suurberg mountain plateau to the Great Fish River
and the semi-arid areas of Eastern Cape
province.
Its inlet takes water from the Gariep Dam
at Oviston: the name Oviston is an acronym based on the Afrikaans Oranje-VISrivier TONnel. With a maximum throughput of 54 m3/s, it supplies to the Teebus Spruit and the Great Brak River and from there to the valleys of the Great Fish River and the Sundays River
. It is the longest continuous enclosed aqueduct in the southern hemisphere and the third-longest water supply tunnel in the world.
The tunnel has a finished diameter of 5.3 metres (17.4 ft) and ranges in depth of between 80 metres (262 ft) and 380 metres (1,247 ft).
Construction started in 1966 and the tunnel opened in 1975.
When the tunnel was completed it was the longest continuous enclosed aqueduct in the southern hemisphere and the second-longest water supply tunnel in the world.
Tunnel
A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...
in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
which diverts water from the Orange River
Orange River
The Orange River , Gariep River, Groote River or Senqu River is the longest river in South Africa. It rises in the Drakensberg mountains in Lesotho, flowing westwards through South Africa to the Atlantic Ocean...
under the Suurberg mountain plateau to the Great Fish River
Great Fish River
The Great Fish River is a river running through the South African province of the Eastern Cape, it originates east of Graaff-Reinet and runs through Cradock, just south of this the Tarka River joins it...
and the semi-arid areas of Eastern Cape
Eastern Cape
The Eastern Cape is a province of South Africa. Its capital is Bhisho, but its two largest cities are Port Elizabeth and East London. It was formed in 1994 out of the "independent" Xhosa homelands of Transkei and Ciskei, together with the eastern portion of the Cape Province...
province.
Its inlet takes water from the Gariep Dam
Gariep Dam
Gariep Dam is a dam in South Africa, near the town of Norvalspont, Free State, province South Africa.-Overview:The Gariep Dam was originally called the Hendrik Verwoerd Dam after the first Prime Minister of the Republic of South Africa Hendrik Frensch Verwoerd on its commission in 1971...
at Oviston: the name Oviston is an acronym based on the Afrikaans Oranje-VISrivier TONnel. With a maximum throughput of 54 m3/s, it supplies to the Teebus Spruit and the Great Brak River and from there to the valleys of the Great Fish River and the Sundays River
Sundays River
The Sundays River is a river in the Eastern Cape Province of South Africa and is said to be the fastest flowing river in South Africa. The Khoisan people originally named this river Nukakamma because the river's banks are always green and grassy despite the arid terrain that it runs...
. It is the longest continuous enclosed aqueduct in the southern hemisphere and the third-longest water supply tunnel in the world.
The tunnel has a finished diameter of 5.3 metres (17.4 ft) and ranges in depth of between 80 metres (262 ft) and 380 metres (1,247 ft).
Construction started in 1966 and the tunnel opened in 1975.
When the tunnel was completed it was the longest continuous enclosed aqueduct in the southern hemisphere and the second-longest water supply tunnel in the world.