Onilahy is a river in Atsimo-Andrefana and Anosy (Toliara Province), southern Madagascar. It flows down from the hills near Betroka to the Mozambique Channel. It empties at St. Augustin (23.5666667°S 43.75°E / -23.5666667; 43.75), and into the Bay of Saint-Augustin.

Onilahy River
Onilahy River estuary
Map of Malagasy rivers (Onilahy flows from the south-central part to the southwestern coast).
Location
Country	Madagascar
region	Atsimo-Andrefana, Anosy
Cities	Mandrofify, Ambolofoty
Physical characteristics
Source
• location	near Betroka
Mouth	Bay of Saint-Augustin
• location	Saint Augustin, Mozambique Channel
• elevation	0m
Length	525 km (326 mi)
Basin size	31600 km2[1]
Basin features
Protection status
Ramsar Wetland
Official name	Zones humides de l'Onilahy
Designated	22 May 2017
Reference no.	2304[2]

Two species of cichlids are endemic to the river basin, but Ptychochromis onilahy is probably already extinct[3] and the remaining range of Ptychochromoides betsileanus covers less than 10 square kilometres (3.9 sq mi).[4][5]

Geography

Sources of the Onilahy river are near Beadabo. It flows through Ankilimary, to Benenitra, Ehara, Bezaha and Antanimena. It is crossed by the RN 10 near Tameantsoa. The mouth of the Onilahy river is situated in the Indian Ocean at Saint Augustin, Madagascar, 35 km south of Toliara (Tuléar).

Its main affluentes from its south are Sakamena river, Evasy, Ianapera river, Isoanala river and Ihazofotsy. From the north these are Sakondry, Taheza, Sakamare and the Imatoto river.

References

На других языках

[de] Onilahy (Fluss)

[it] Onilahy

[ru] Унилахи