Grand ethiopian renaissance dam reservoir filling

Abstract

The Grand Ethiopian Renaissance Dam (GERD) is expected to create a reservoir of 73 bcm (billion cubic meter) covering an area of 1883 km2 stretching 246 km upstream. The reservoir will be half the size of the upstream Lake Tana. After the surprise launching of the construction of GERD, the controversy around GERD quickly evolved from its engineering design and construction aspect to the impact of filling on the Sudan and Egypt. One of the controversies with Egypt is the number of years for initial reservoir filling, as shorter filling time requires more flow reduction and higher investment return from the dam. Longer filling time requires lower flow reduction and lower investment return from the dam. In this chapter, reported and synthetically generated stream flow data were used to estimate required period of time for initial reservoir filling. Results suggest that eight to nine years is likely required to fill the reservoir with 20% of the annual flow of each year held back. With a historical average Nile annual flow of 84 bcm at Aswan, the 132 bcm volume of the High Aswan Dam took six years (1971–1976) to reach full capacity with full river flow. Historical average Nile annual flow at Aswan is 84 bcm.