As Ethiopian dam fills, tensions rise

Ursa is monitoring reservoirs in Ethiopia and Sudan impacted by the construction of the Grand Ethiopian Renaissance Dam, a mega-project on the Nile’s main tributary with wide-ranging consequences.

We are measuring these reservoirs using satellite radar imagery, similar to previous work we’ve done monitoring Iraq’s water crisis.

Fluctuations in size are normal, as a result of seasonal rainfall patterns, but over the last few weeks another element is at play after Ethiopia began filling the Grand Ethiopian Renaissance Dam (GERD).

Our calculations show the surface area of the water backed up by GERD has increased 1,812% in a little more than 3 weeks through July 21. 

Some 100 km downriver, across the border in Sudan, the opposite trend is occurring. Over roughly the same period, the reservoir at Roseires Dam has seen a 25% reduction.

A time lapse video of satellite imagery, shown below, reveals the changes at GERD and Roseires Dam since late June.

The water surface area at GERD equaled 178.7 square kilometers July 21, up from 50.1 km2 July 9 and 9.3 km2 June 27, according to our measurements (Figure 1).


Figure 1

Figure 1

At the Roseires Dam, in Sudan, our measurements show the water surface area was 124 km2 July 20, compared with 157.1 km2 July 8 and 166.8 km2 June 26 (Figure 2).


Figure 2

Figure 2

The satellite images above come from synthetic aperture radar (SAR), which works regardless of weather conditions or time of day. 

Cloud coverage isn’t a problem with SAR. That’s an important distinction in this case since the rainy season in Ethiopia often lasts from June through September.

The regulation of the Blue Nile, which converges with the White Nile in Khartoum to form the Nile River, has become a flashpoint involving Ethiopia and its downstream neighbors -- Sudan and Egypt.


GERD regional.PNG

For Sudan and Egypt, in particular, the issue of water security is inextribably tied to the Nile River. Egypt’s 100 million people rely on the Nile for 90% of the country’s water needs.

Since plans for GERD were first announced in 2011, Cairo has viewed the project as a serious threat to the country’s water supply.

Rounds of talks made halting progress, but failed to achieve a breakthrough. 

Then came reports, in early July, noting the dramatic increase in the GERD reservoir. 

Ethiopia tried deflecting responsibility, saying water levels were rising on account of heavy rainfall. 


The Grand Ethiopian Renaissance Dam straddles the Blue Nile

The Grand Ethiopian Renaissance Dam straddles the Blue Nile

But on July 21, Prime Minister Abiy Ahmed acknowledged on Twitter that Ethiopia had indeed been filling the reservoir, saying the first year target had been met.

The reservoir is expected to take 5-7 years to fill completely, while construction on the dam should be finished by 2022 or 2023.

For Ethiopia, GERD is considered an economic game-changer. The $4 billion hydroelectric dam will become Africa’s largest, with a capacity to generate 6.4 gigawatts of electricity. 

What comes next? 

The worst case scenario involves military conflict, though fortunately, diplomacy remains alive.  African Union-mediated talks resumed July 27 and will take place again the following week.

Check back for updates on this story. In the meantime, explore these story maps describing our capabilities as well as insights related to the economic impact of COVID-19.

Geoffrey Craig