The dam that divides Ethiopians

The Gibe III dam is under construction on the Omo River, approximately 300km southwest of Addis Ababa. It is the third in a series of cascading hydroelectric projects in the region.

The first, the Gilgel Gibe dam (also called Gibe I), was completed north of the Gibe III dam site in 2004. The Gibe II project is a power plant associated with the Gibe I dam that is still under construction.

The new Gibe III dam is expected to produce 6500 GWh of energy a year, and surplus energy is expected to create 300 million euros (£282m; $407m) in revenue, according to the Ethiopian Electric Power Corporation (EEPCo), the sole provider of power in Ethiopia.

Ethiopia's neighbours, such as Djibouti, Yemen, Kenya, Uganda, Sudan and Egypt, would all be in a position to purchase the excess energy.

EEPCo sees another benefit of the project in regulating the flow of the river, which floods annually, and thereby making it navigable all year.

The resulting reservoir of approximately 200 sq km would be used as a fishery, according to an environmental and social impact assessment by EEPCo.

FLOODING EFFECT OF DAM ON OMO RIVER

Choose a view: At present  With dam built

However, some argue that the seasonal floods are integral to the lifestyles of many of the Lower Omo Valley's 500,000 inhabitants.

A report by International Rivers, an environmental and human rights organisation based in California, says the practice of flood retreat cultivation is central to the lives of people along the Omo River.

The report says families plant riverbank plots as the floods begin to retreat; harvesting takes place a few months later. The silt-laden floodwaters mean additional fertilisers are not needed.

International Rivers says the size of cultivated areas can vary year to year depending on the height of the flood, but the reliability of the harvest makes it a fundamental practice for the region's food security.

The Gibe III dam, now under construction, is expected to begin producing power in July 2011.