Ikopa
| Ikopa | ||
 River systems in Madagascar |
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| Data | ||
| location | Madagascar | |
| River system | Betsiboka | |
| Drain over | Betsiboka → Indian Ocean | |
| origin | Confluence of the Northern and Southern Varahine 19 ° 1 '21 " S , 47 ° 44' 45" O |
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| Source height | 1810 m (source of the Varahina) | |
| muzzle | at Antananarivo in the Betsiboka coordinates: 16 ° 47 ′ 55 " S , 46 ° 51 ′ 20" E 16 ° 47 ′ 55 " S , 46 ° 51 ′ 20" E
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| length | 485 km | |
| Catchment area | 18,550 km² | |
| Left tributaries | Kotoratsi, Isandrano, Menavava, Sisaoni, Andromba | |
| Right tributaries | Manankazo, Andranobe, Namokomita, Mamba | |
| Flowing lakes | Ambohibao, Ivato, Mahazoarivo, Mandroseza | |
| Reservoirs flowed through | Tsiazompaniry Dam; Mantasoa Dam; Antelomita Reservoirs (2) | |
 Pirogues on the Ikopa near Antananarivo |
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The Ikopa is a river in the northwest of Madagascar with a length of 485 km. It is the most important tributary of the Betsiboka with a catchment area of 18,550 km². The Ikopa also flows through the southernmost suburb of the capital Antananarivo .
course
The Ikopa arises from the confluence of the Northern and Southern Varahine . The most distant source is at the Angavokely rock in the Andramasina sub-prefecture at an altitude of 1810 m above sea level . There the river is named Varahina . 6 km after the confluence of the two source rivers, the Ikopa falls over the Antelomita waterfalls, which were dammed up to generate electricity (approx. 50 km southeast of Antananarivo near Manjakandriana ) from the Ankaratra . Two more dams were built to regulate water on the north of Varahine : Mantasoa (1938) and Tsiazompaniri (1956). There are more hydropower plants in a confined space at Mandraka and Ampasimpotsi , as the river in this area drops by 250 meters, and later at Antelomita by another 36 meters.
During the Antelomita Falls , two hydropower plants were built in 1909 and 1918 to supply electricity to the capital, Antananarivo. From Antelomita the Ikopa initially runs in a west-east direction in a relatively narrow deep gully with a slope of about 2 m / km to Ambohimanambola . There he reaches the plateau of Antananarivo. There the slope becomes smaller and sinks to 25 cm / km and 13 cm / km at the tributary of the Andromba river .
Several rivers flow into the Ikopa on the Antananarivo plateau: from the left Sisaoni and Andromba and from the right Mamba . There the river also forms larger areas of water: Ambohibao , Ivato , Mahazoarivo and Mandroseza .
From the plateau of Antananarivo, the river pours onto the plateau of Betsimitatatra from the Bevomanga-Farahantsana mountain, it again flows through a series of rapids and cataracts. The most important of these is the Antanandava Falls at Farahantsane , 37 m high. Up to Farahantsane the catchment area of the Ikopa covers approx. 4,498 km². Below Farahantsane from the Antanandava Falls, the river leaves its bed of crystalline, hard rock and pours over a series of large waterfalls. The first large waterfall is located at Ranomafana Waterfall 44 km from Farahantsana. There the river falls 40 m over a distance of 1 km. After another 14 km, it crosses the Ambilobe massif, where it drops 160 m at the Mahavola waterfall over a distance of 6 km. After 32 km the Vohitsara waterfall (100 m by 5 km) and after 9 km the Isandrano waterfall (50 m by 4 km) are on the river route. After 44 km comes the Antafofo waterfall (180 m on 10 km). The last big rapids is Antanandava (135 m over 10 km). From there the Ikopa runs to the northwest at an altitude of only 50 m above sea level. It is only 31 km to the confluence with the Betsiboka. The river bed becomes very wide, up to 3 km in places, and the water meanders and is sometimes very blue in color. The incline is only about 26 cm / km.
Hydrology
The main tributaries are the Kotoratsi , Isandrano and Menavava (left) and Manankazo , Andranobe and Namokomita (right). The Ikopa has a clearly structured profile with three main sections:
- On the first section to Farahantsana, the Ikopa is a typical mountain river with a steep gradient.
- In the second section from Farahantsane over the next 296 km, the Ikopa has a strongly varying character due to the different nature of the landscape. On this stretch it drops from 1150 m to 50 m above sea level.
- In the third section from Antanandava the river comes into flat terrain, the gradient is only an average of 50 cm / km, and on the last 20 km even only 26 cm / km (only a third of the gradient of the Betsiboka in the same section)
In terms of its topographical and geological properties, the river has the greatest potential for hydropower in Madagascar, estimated at 15,000,000 kWh / year.
Individual evidence
- ↑ a b c d e M. ALDEGHERI: Rivers and streams on Madagascar, in the portal madadoc.mg (29 August 2011.) ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ a b Rivers of Madagascar in the mapsofworld portal ( memento of the original from September 22, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Mantasoa Dam, In: Industryabout (August 30, 2011.)
- ↑ Tsiazompaniry: Une nouvelle destination découverte à Tanà, In: Biodiversityreporting (August 30, 2011.)
