The roughly 120 km long river rises on the western slopes of the Soka Sonicha mountain range (with the most prominent being the Gelala mountain) at 6°48′N 38°36′E / 6.8°N 38.6°E / 6.8; 38.6, flows west first and then for most of its course southwards along the eastern floor of the Great Rift Valley and through the Sidama Zone.
The river turns westward when entering the Gidabo flood plains directly east of Lake Abaya.
In the flood plains and along the final stretch of the river it defines the southern border of the Sidama Zone through which it flows for most of its length.
A special feature of the Gidabo catchment area is the existence of a large number of springs, which can be used as groundwater sources for agriculture even during the summer and winter dry seasons.
17 kilometers by road west of Dilla, where the river turns westward before entering its flood plains and marshes, the Gidabo dam, a 21.3 meter high and 350 m wide earth fill embankment dam is used for flood control and for irrigation purposes of an area of 27 km2 downstream as well as for fish production.