page_title: Grand Ethiopian Renaissance Dam
section_title: Engineering questions
hierarchical_section_title: Grand Ethiopian Renaissance Dam / Controversies / Engineering questions
caption_attribution_description: English: Men at work on the Grand Ethiopian Renaissance Dam project. This is an image of "African people at work" from Ethiopia
context_page_description: The Grand Ethiopian Renaissance Dam, formerly known as the Millennium Dam and sometimes referred to as Hidase Dam, is a gravity dam on the Blue Nile River in Ethiopia under construction since 2011.
  The dam is in the Benishangul-Gumuz Region of Ethiopia, about 15 km east of the border with Sudan.
  The primary purpose of the dam is electricity production to relieve Ethiopia’s acute energy shortage and for electricity export to neighboring countries. With a planned installed capacity of 6.45 gigawatts, the dam will be the largest hydroelectric power plant in Africa when completed, as well as the seventh largest in the world.
  The filling of the reservoir was scheduled to begin in July 2020.
  Once completed, the reservoir will take between 5 and 15 years to fill with water, depending on hydrologic conditions during the filling period and agreements reached between Ethiopia, Sudan, and Egypt.
context_section_description: In 2012, the International Panel of Experts was formed with experts from Egypt, Sudan, Ethiopia, and other independent entities to discuss mainly engineering and partially impact related questions. This panel concluded at a number of engineering modifications, that were proposed to Ethiopia and the main contractor constructing the dam. One of the two main engineering questions, dealing with the size of flood events and the constructive response against them, was later addressed by the contractor. The emergency spillway located near the rock saddle dam saw an increase of the rim length from 300 m to 1,200 m to account even for the largest possible flood of the river. The second main recommendation of the panel however found no immediate resonance. This second recommendation dealt with the structural integrity of the dam in context with the underlying rock basement as to avoid the danger of a sliding dam due to an unstable basement. It was argued by the panel, that the original structural investigations were done with considering only a generic rock mass without taking special conditions like faults and sliding planes in the rock basement (gneiss) into account. The panel noted, that there was indeed an exposed sliding plane in the rock basement, this plane potentially allowing a sliding process downstream. The panel didn't argue that a catastrophic dam failure with a release of dozens of cubic kilometers of water would be possible, probable or even likely, but the panel argued, that the given safety factor to avoid such a catastrophic failure might be non-optimal in the case of the Grand Ethiopian Renaissance Dam. It was later revealed that the underlying basement of the dam was completely different from all expectations and did not fit the geological studies as the needed excavation works exposed the underlying gneiss. The engineering works then had to be adjusted, with digging and excavating deeper than originally planned, which took extra time and capacity and also required more concrete.
caption: Dam construction in 2014
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