A hidden component of the recent agreement between Egypt and Ethiopia in regards to the Nile waters has recently been revealed, reports NewScientist (30 May 2015, paywall):
The solution involves reducing the losses to evaporation from Lake Nasser, the reservoir behind Egypt’s Aswan High Dam in the Nubian desert. Up to 16 cubic kilometres of water evaporate annually from its surface – a quarter of the Nile’s average flow and up to 40 per cent in a dry year.
Storing more of that water in the reservoir behind Ethiopia’s dam could cut those losses, as it is deeper, has a surface area less than a third as great and sits in the cool and wet highlands. But it would also cut Egypt’s electricity generation, so Ethiopia would need to share electricity from its new dam, says Kenneth Strzepek at the Massachusetts Institute of Technology.
Sudan, too, could benefit from the dam and a more even water flow, reducing the risk of flooding and increasing the potential for irrigation. “The government of Sudan is already selling land leases for new farmland by the river,” says Alex de Waal of the World Peace Foundation at Tufts University in Boston.
