Sunday, August 9, 2020

"Will Ethiopia’s Disputed Dam Collapse?"

Sooner would be better than later if it is to happen.
From the American Geophysical Union's Eos Magazine, August 6:

Satellite imagery shows water filling the Grand Ethiopian Renaissance Dam’s reservoir, amid concerns over its safety and political fallout.
Located downstream from the headwaters of the Abay, or Blue Nile, River in the Ethiopian Highlands, the Grand Ethiopian Renaissance Dam (GERD) is set to become Africa’s largest hydroelectric power plant. Still under construction, it is eventually expected to be able to generate more than 6,000 megawatts of electricity, which will provide power for about half of Ethiopia’s population and also allow the country to export electricity to neighboring nations. Ethiopia has argued it needs the dam’s electricity to modernize and grow.
The dam would affect the flow of the Nile to downstream residents in Sudan and Egypt and has become a major point of contention over water rights along the river. Scientists and engineers have also voiced concerns over the dam’s structural integrity because of its location in a mountainous terrain in an active tectonic region.
As satellite imagery shows the dam’s reservoir beginning to fill, Ethiopia, Sudan, and Egypt are negotiating to reach a political consensus on safe operational management to ensure health and sustainability in the region.

Damming Water in an Unstable Terrane?
The dam will ultimately create a reservoir with a capacity of 74 billion cubic meters of water. Since construction began in 2011, the project has been contentious among Ethiopia, Sudan, and Egypt, as 74 billion cubic meters of water is coincidentally what Sudan and Egypt negotiated in the 1959 Nile Waters Agreement. (That agreement’s allotment includes the flows of both the Blue Nile and the White Nile, which meet at a confluence near Khartoum, Sudan. The northward flow of the White Nile from Lake Victoria, a much lower volume than the Blue Nile, remains largely unimpeded.)

 Some engineers have cited research suggesting that the dam is vulnerable to environmental hazards that may cause it to collapse. Seismicity is not the least of these concerns, as the project abuts one of the largest rift zones on Earth: the Great Rift Valley.

“Ethiopia is the most seismically active African country,” said Abbas Sharaky, a professor of geology at Cairo University. In the past 5 years, Ethiopia has had at least five earthquakes measuring from M4.0 to M5.3. “The dam itself and its reservoir are located on a fault.…[Part of the dam] is arched so that the concave side faces the lake, making it weak and vulnerable to collapse.”....