The Mananara South is formed by the merger of the Menarahaka, Itomampy, and Ionaivo. The Ionaivo rises on the slopes of Tsimahamory peak, at an approximate elevation of 1500m. The Itomampy rises not far from the Ionaivo, about 40 km from the Indian Ocean, at approximately 1600m, and runs north until it joins the Ionaivo. The Menarahaka rises in the Andringitra massif, at approximately 2000m elevation. It is joined by the Sahambano before joining the Ionaivo.[3]
^"Madagascar-GEOGRAPHY". countrystudies.us. U. S. Library of Congress. Retrieved 27 September 2017.
^Aldegheri, Marius. Rivers and Streams on Madagascar, in Battistini, Rene & G. Richard-Vindard (ed.), Biogeography and Ecology in Madagascar, p. 266-67 (1972))