Resolving Mega-Dams Energy-Water Nexus in the Eastern Nile Basin During Prolonged Droughts

Abstract Optimizing hydropower generation from mega-dams during prolonged droughts while minimizing downstream water deficits is decisive to resolving the ongoing major conflict on transboundary river management in the highly populous Eastern Nile basin. Our study provides comprehensive assessments of the efficiency of multiple drought-mitigation operation policies based on the outcomes of negotiations. In addition, we develop four novel policies that reduce potential adverse downstream impacts and maximize upstream hydropower generation during prolonged droughts. We use a multi-reservoir hydraulic-energy model with the most up-to-date entries to simulate and optimize the hydropower generation and reservoir level response of the two Nile's largest mega-dams, Grand Ethiopian Resonance Dam (GERD) and Aswan High Dam (AHD), utilizing 100 years of historical flow records. Our results show that, during wet and average flow conditions and a temporary drought, GERD can generate maximum hydropower without a noticeable downstream deficit. However, for prolonged droughts, GERD can still generate sustainable energy from more than 87% of its maximum hydropower while minimizing the dam-induced downstream water budget deficit to a manageable volume. Our up-to-date findings can reduce the negotiations' disparities on operating Nile’s hydropower mega-dams during prolonged drought and help reach a collaborative framework to mitigate the threats of rising hydroclimatic fluctuations.