Trade-offs between hydropower and irrigation in transboundary river systems: the implications of further development on the Blue Nile in Ethiopia

Abstract We evaluate the implications of constructing one or two large dams upstream of the Grand Ethiopian Renaissance Dam (GERD), possibly in combination with new irrigation schemes upstream of these Blue Nile hydropower facilities. Two new dams could increase average annual hydropower on the Blue and Main Nile by almost 50% (30.2 TWh/yr to 44.7 TWh/yr). A system-wide analysis of the expected financial benefits of various development scenarios reveals little financial justification for substantial irrigation water withdrawals upstream of the GERD and multi-dam cascade. Withdrawing 5 billion cubic meters annually upstream of the GERD would reduce basin-wide hydropower by 3.3 TWh/year; withdrawing this volume above three dams would cause a 6.8 TWh/yr reduction. 1 (5) bcm/yr of withdrawals upstream of the three dams would reduce the reliability of meeting a 55.5 bcm/yr release target from the High Aswan Dam Reservoir by 3 (37) %.