The Past and the Future of Flood Management in the Eastern ... - INBO

Figure (5) Nile River Basin in Ethiopia
The Akobo River defines the border with Sudan, access is very difficult from the
Ethiopian side, and there are no river gauges on the Akobo River in Ethiopia. The Akobo
from the south- east joins the Pibor flowing from the south out of Sudan, and the Pibor
then defines the Ethiopian- Sudan border until where it is joined by the Baro flowing the
east out of Ethiopia. The river then becomes the Sobat, and flows west through southern
Sudan to its confluence with the White Nile about 800 km south of Khartoum. The only
dam in the Baro- Akobo sub-basin is the Abobo Dam on the Alwero River tributary,
commissioned in 1996. The catchment area to the dam is 1 043 km 2 , and the maximum
storage capacity is only 74 MCM. Regular widespread flooding occurs seasonally in the
flat plain areas up-stream of the Sudan border.
The Abbay River flows out of Lake Tana at Bahir Dar, and spirals first south, then west,
and finally north-west into the Sudan. On the way it is joined by many large tributaries,
including the rivers Beshilo, Jimma, Muger, Guder, Finchaa, Didessa and Dabus on the
left bank, and the Beles River on the right bank. The Abbay passes through deep valleys
and gorges as a raging torrent during and after the wet season (July to October
approximately), conveying large sediment loads. In the Sudan the Abbay is known as the
Blue Nile.
Apart from a weir (Chara Weir) at the outlet of Lake Tana used to regulate lake outflows
for a hydroelectric station at the Blue Nile Falls, there are no dams on the Abbay River;
however the potential for hydropower dams downstream is currently being investigated.
There is one dam on the Finchaa River tributary competed in 1973, where the catchment
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