The Nile is the longest river in the world, flowing through eleven countries and various climates, landscapes, and economies. It crosses five climatic zones — equatorial, humid, semi-arid, arid, and Mediterranean — making it a crucial freshwater resource, particularly for countries in the dry Eastern Sahara.
A key challenge in managing the Nile is optimizing hydropower generation from upstream dams during long droughts while avoiding water shortages downstream. This issue is central to the ongoing Eastern Nile River Basin water conflict. Despite a decade of negotiations, uncertainties have hindered progress in managing the Grand Ethiopian Renaissance Dam during extended dry periods.
A new study presents a scientific framework for managing the Nile’s large dams during prolonged droughts. The goal is to balance hydropower generation with minimizing water shortages for communities downstream.
The research evaluates the effectiveness of various drought-mitigation strategies for operating the Nile’s mega-dams.
Nile upstream hydropower dams will provide electricity to 60% of Ethiopia’s population, while 98% of Egypt’s annual renewable water resources come from the same river. The upstream is in desperate need of energy, and the downstream is in dire need of water.
Corresponding author Essam Heggy adds, “After over a decade of negotiations, no cooperative framework for dam operations has been established due to the lack of a comprehensive assessment of how the mega-dams affect upstream and downstream interests during prolonged droughts. These droughts are expected to worsen, leading to severe consequences for the river’s riparian countries.”
The Nile river could be 30 million years old
The challenge is figuring out how to manage the Grand Ethiopian Renaissance Dam (GERD) during extended droughts and accurately predict the resulting impacts on the Nile’s dams both upstream and downstream.
The new study redefines the concept of prolonged drought and proposes an ideal operational policy for the Grand Ethiopian Renaissance Dam (GERD) to generate sustainable energy. The framework recommends allowing approximately 87% of GERD’s optimal hydropower production without causing a downstream water deficit for Egypt, even during hydro-climatic extremes.
The authors aim to enhance the resilience of the more than 300 million people in the Eastern Nile Basin, who face highly uncertain climatic conditions against prolonged droughts.
Heggy and colleagues from the Catholic University of Louvain, Northern Michigan University, NARSS, and the National Research Centre in Egypt used an updated hydraulic model to evaluate the effectiveness of various policies addressing the uncertainty of upstream dam impacts during prolonged drought. They analyzed 100 years of historical data and simulated several operation strategies to balance sustainable hydropower generation while minimizing water stress downstream.
Their simulated policies focus on the key issue: finding solutions by clearly defining prolonged drought in the Eastern Nile Basin using one key measure: the critical level of the Aswan High Dam. Heggy cites other studies to highlight the differing definitions of drought used by countries in the region.
The Nile in Egypt has two main branches: the Blue Nile from the Ethiopian Highlands, which provides over 80% of the river’s flow, and the White Nile from Lake Victoria, which contributes the rest.
Heggy and colleagues suggest that policymakers should use the Aswan High Dam level as the main indicator instead of using the Blue Nile’s current flow to measure drought. They propose that drought should be declared when the dam’s level drops to 165 meters (~78 billion cubic meters), and mitigation measures should begin.
According to the authors, this approach can resolve disagreements over what defines “dry years” and “flow volume” by incorporating both the White and Blue Nile flows. They also propose an optimized policy in which the Grand Ethiopian Renaissance Dam can still produce over 87% of its optimal hydropower without causing a downstream water deficit in Egypt.
Mohamed Ramah, a PhD researcher at the Catholic University of Louvain, added, “Only by assessing both upstream hydropower and downstream water needs can the conflict be resolved, rather than just pushing for more upstream dams without considering downstream water deficits.”
Heggy emphasized, “Sharing the Nile’s water and hydropower resources amid uncertain climate forecasts calls for policymakers to work together with open science to ensure peace and prosperity.”
Journal Reference:
- Heggy, E., Abotalib, A.Z., You, J. et al. Grand Ethiopian Renaissance Dam can generate sustainable hydropower while minimizing downstream water deficit during prolonged droughts. Commun Earth Environ 5, 757 (2024). DOI: 10.1038/s43247-024-01821-w
