Lac Alaotra

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Lac Alaotra
Lake Alaotra NASA.jpg
Geographical location Madagascar
Tributaries Ambato
Drain Ambato
Data
Coordinates 17 ° 28 ′  S , 48 ° 31 ′  E Coordinates: 17 ° 28 ′  S , 48 ° 31 ′  E
Lac Alaotra (Madagascar)
Lac Alaotra
Altitude above sea level 750  m
surface 900 km²
volume 0.945 km³dep1
Maximum depth 1.50 m
Middle deep 0.60 m

particularities

Lake in wetland

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Lake Alaotra (French: Lac Alaotra ) is the largest lake in Madagascar . It is located in one of the most seismically active regions of Madagascar at an altitude of 750  m approx. 100 km from the east coast of Madagascar in the Alaotra-Mangoro region (formerly Toamasina ) in the rift valley between the central highlands and the east coast of Madagascar, that of Ambatondrazaka and Amparafaravola runs towards Antananarivo . The name Alaotra is derived from the Indonesian word for "sea".

The lake has an area of ​​220 km² and in the rainy season floods another 350 km² in the south and west. It has the rough shape of a boomerang and is located in a huge wetland area that is used extensively for growing rice . The valley is one of the centers in Madagascar where lavakas occur, a special form of soil erosion. This form of erosion, favored by clearing , overgrazing and burning of pastures, means that the already shallow lake (average depth approx. 2 m) is increasingly silting up .

The lake is fed by the Ambato River , which also drains it and flows into the Indian Ocean after 381 km .

fauna and Flora

One of the special features of the fauna of Lac Alaotra is a high concentration of Madagascar ducks , a species of swimming duck that is endemic to Madagascar and whose populations have declined sharply in recent years. The Delacour Little Grebe, endemic to Lake Alaotra, is most likely extinct. The number of Madagascar dwarf divers that were at home here in historical times has also decreased significantly. In addition, a primate species, the Alaotra bamboo lemur , only occurs in the reed belt around the lake. Another animal endemic to the lake is Salanoia durrelli from the Madagascar mongoose family .

Individual evidence

  1. ↑ Rónadh Cox, Danielle B Zentner, Amos Fety Michel Rakotondrazafy and Christine Fara Rasoazanamparany; (2009) Shakedown in Madagascar: Occurrence of lavakas (erosional gullies) associated with seismic activity ; Manuscript submitted for publication
  2. ↑ a b c d e Franz Stadelmann, Madagascar: Symbiosis between yesterday and today ; On-line
  3. ↑ a b NRG Voarintsoa, ​​Rónadh Cox, MOM Razanatseheno and, AFM Rakotondrazafy; Relation between Bedrock Geology, Topography and Lavaka Distribution in Madagascar ; South African Journal of Geology, 2012, Vol. 115.2 ( doi : 10.2113 / gssajg.115.225 ); Page 225-250; On-line
  4. ↑ Janet Kear (Ed.): Ducks, Geese and Swans . Oxford University Press, 2005, ISBN 0-19-854645-9 , p. 544.
  5. ↑ BirdLife Factsheet (accessed July 9, 2009)