Risk analysis and seismic risk assessment of ten hydropower dams in Ethiopia

Risk analyses can be undertaken for single projects or a portfolio of dam projects; for single hazards, such as floods and earthquake ground shaking, or for all possible hazards (natural hazards, man-made hazards and site-specific and project-specific hazards). Usually, risk analyses are done for the flood hazard and the seismic ground shaking hazard. These can be described reasonably well by statistical methods but the results of such specific hazard analyses do not provide a complete picture of the total risk of a large dam project. In this paper, the seismic risk of ten large hydropower dams in Ethiopia is presented. The dams include concrete gravity and arch dams and different types of embankment dams. In the risk analyses, the seismic hazard is represented by the peak ground acceleration with a return period of 10 000 years. Based on these results, recommendations are made either for further studies or intervention measures to reduce the risk.