The World's Largest Saddle Dam at Risk: Multisensor Geohazard Analysis and Downstream Impacts

Authors

Hesham el-Askary, Chapman UniversityFollow
Hesham Morgan, Chapman University
Surendra Maharjan, Chapman UniversityFollow
Ali Elgendy, University of Szeged
Wenzhao Li, Chapman UniversityFollow
Rejoice Thomas, Chapman UniversityFollow
Austin Madson, Yale University
Cyril Rakovski, Chapman UniversityFollow

Document Type

Article

Publication Date

2-5-2026

Abstract

The Grand Ethiopian Renaissance Dam (GERD) Saddle Dam, which holds approximately 89% of the main reservoir's live storage, is one of the largest and most critical auxiliary dams globally; its construction on Ethiopia's Blue Nile has consequently raised significant regional and international concerns regarding potential environmental impacts and geohazard risks. This study presents a comprehensive risk assessment of the GERD Saddle Dam by integrating high-resolution satellite data (GRACE, Sentinel-1, Sentinel-2, WorldView-3), hydrological modeling (SWAT), Persistent Scatterer Interferometry (PSI), geospatial analysis, and advanced statistical techniques. The results highlight critical structural vulnerabilities, including groundwater infiltration estimated at approximately 41 ± 6.2 billion cubic meters during reservoir filling, differential settlement of up to 40 mm, and emerging seepage and leakage pathways. Moreover, anomalous seismicity spatially aligned with pre-existing fault systems has been observed, with Poisson regression analysis indicating increased regional seismicity potentially linked to volcanic activity and the reservoir impoundment process, underscoring the dam's transboundary geohazard risks. A dam-breach simulation reveals catastrophic downstream flood risks extending to Sudan and Egypt, with potential impacts on millions. These findings underscore the urgent need for international risk monitoring frameworks and contribute to advancing global dam safety protocols and Sustainable Development Goals (SDGs 9, 11, and 13).

Comments

This article was originally published in International Journal of Disaster Risk Reduction , volume 135, in 2026. https://doi.org/10.1016/j.ijdrr.2026.106045

Recommended Citation

H. El-Askary, H. Morgan, S. Maharjan, A. Elgendy, W. Li, R. Thomas, A. Madson, C. Rakovski, The world's largest saddle dam at risk: Multisensor geohazard analysis and downstream impacts. Int. J. Disaster Risk Reduct. 135 (2026) 106045, https://doi.org/10.1016/j.ijdrr.2026.106045

Peer Reviewed

1

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This work is licensed under a Creative Commons Attribution 4.0 License.