Environmental and Social Impact Assessment - Gibe III

Gibe III – Environmental and Social Impact Assessment 300 ENV R CS 002 C - A9003099
Part of the Chida-Sodo road from Bele town to Lala area will be relocated since the existing bridge on the
Chida Sodo road, crossing the river Omo at a low level, will be submerged by the reservoir. The foreseen
“relocation road” will be opened for construction purposes and will therefore become available for public use
while completing the impounding of the reservoir (see Figure 3.3).
This permanent link will therefore include:
Figure 3.3: Access road to the dam site
• a 24.5 km road on the right bank starting at a small village called Yello nearby Lala;
• the foreseen Omo bridge which crosses the river slightly d/s of the dam;
• a 54.8 km road on the left bank ending about 4 km west of Bele.
3.6 River Diversion
3.6.1 Layout
The diversion scheme is designed to divert floods up to about 5,200 m 3 /s (30 years return period) during the
construction period of the dam and the Power House.
The Omo river will be detoured into three hydraulic tunnels along the right abutment by means of two
cofferdams on the river bed.
The river diversion will be achieved in two stages:
• stage 1: river closure – dry season diversion
• stage 2: river diversion
The river closure will divert the flows from the dam site area, during the cofferdams construction period, by
means of the pre-cofferdams on the Omo River and the TL diversion tunnel.
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