INTERVIEW: Can the GERD handle the pressure?

Karima Abdel-Ghani , Thursday 4 Nov 2021

Earth systems scientist Hesham El-Askary explains to Al-Ahram Weekly why the Grand Ethiopian Renaissance Dam cannot hold the targeted 74 bcm of Nile water

Can the GERD handle the pressure

Hesham El-Askary is a professor and director of Computational and Data Science Graduate Programmes at the Schmid College of Science and Technology at Chapman University in the US, with a focus on global climate change, Earth systems, remote sensing, aerosols, natural disasters, and marine habitats.

In 2015, he was the recipient of Chapman University’s elite Senior Wang-Fradkin Professorship award, and he has published over 100 refereed research publications and book chapters, with studies including “An Assessment of the Filling Process of the Grand Ethiopian Renaissance Dam [GERD] and its Impact on the Downstream Countries”.

The study, to which 10 researchers from different universities worldwide contributed, was published this year in the prestigious US journal Remote Sensing. Negotiations on the GERD and its effects on the downstream countries have been taking place for 10 years. Ethiopia insists that the dam on the Blue Nile is crucial to its economic development and will provide power to its population.

Egypt considers the GERD to be a threat to its share of the Nile’s water, and Sudan is concerned about the safety of the dam and its impact on its own dams. In an interview with Al-Ahram Weekly, El-Askary said he had worked on his paper on the GERD out of his conviction of the justice of the Egyptian cause and the balanced stance the country has adopted in the face of Ethiopian intransigence and misguided claims on the right to development and energy generation.

In Egypt, population is a major issue, rendering the need to provide water sources vital, according to El-Askary. Desalination plants and schemes to recycle agricultural wastewater and other wastewater, in addition to underground water and rain, can only provide three per cent of Egypt’s water needs. For the remaining 97 per cent, Egypt depends on transboundary Nile water coming from Ethiopia, he explained.

Egypt does not object to Ethiopian efforts for development purposes and for improving livelihoods, prosperity, and energy generation, but “it is not acceptable to sacrifice the lives of 110 million people under the pretext of the development and prosperity of the Ethiopian nation,” El-Askary said.

He was determined to work on the issue when Ethiopia insisted on the first filling of the dam without consulting Egypt and Sudan or even acknowledging their right to be consulted according to the 2015 Declaration of Principles on the GERD.

He and his team started to think something was not right when Ethiopia said it had attained its second-year target for filling the GERD. “Based on the satellite images we got, this was entirely untrue. Ethiopia had not completed the construction of the dam and could not have possibly attained its filling target,” he said.

The team began to review the data and past and present satellite images, which confirmed that the water rates in the second filling were less than Ethiopia claimed. River-flow data showed that during the GERD’s second filling the rain was heavy, yet Ethiopia could not attain its target primarily because construction on the dam was not advancing as scheduled, and this was confirmed by the research team during its study.

Also confirmed was the previous suggestion that there was a defect in the dam’s structure preventing the acceleration of the storing of water.

El-Askary points out that the GERD is in fact two dams. The first is made of concrete, and its task is to lock up water along 2km of the Nile’s course. The second is made of a rocky cumulus. By reviewing the dimensions of the two dams, the team became certain that while they are huge structures, they are not suitable to hold the huge quantities of water planned to be stored behind them.

This was proven by the team’s work on satellite images, which not only depend on the electromagnetic spectrum from the sun, but also have the ability to send rays that detect what is beneath the surface of the Earth. “We sent time-series flashes of rays and obtained images that we studied to identify the Earth’s crust where the two dams are located and to calculate the differences in the ground, be they negative and positive, and when there is an uplift or subsidence,” El-Askary said.

The team also worked on different sectors of the two dams using radar to determine vertical differences with an accuracy of up to 1cm and to monitor ground displacements and subsidence in the concrete dam with a high degree of accuracy. To ensure optimal accuracy, the team referred to satellite images after 2016, thus collecting five-year data to pinpoint the differences that had been occurring in the two structures of the two dams and the Earth’s crust.

“We focused on the sides of the concrete dam, which were fully constructed, and we found subsidence in the eastern and western parts. The bigger problem is that the subsidence in both areas is not balanced — there is a clear slope — and the subsidence did not occur at the same rate, which indicates the lack of homogeneity in the subsidence. The subsidence became crystal clear with the first filling of the GERD and the increase in water levels in the concrete dam, which is a matter of grave concern,” El-Askary said.

According to data and satellite images, there is not a drop of water in the cumulus dam. For water to be stored there, some 18.5 billion cubic metres (bcm) of water has to be stored behind the concrete dam before reaching the cumulus dam and fully filling the 74 bcm reservoir.

The question was what kind of pressure was causing subsidence in the cumulus dam. After studying the region’s geological characteristics, rifts and weak areas were discovered in the Earth’s crust below the dam, allowing the team to identify subsidence.

“If there is subsidence under the cumulus dam that has not yet stored a cubic metre of water, what is it going to be like when it stores anything between 10 bcm and 74 bcm? Will the cumulus dam be able to take all that pressure,” El-Askary asked. “If Ethiopia were to store 74 bcm of water in the GERD reservoir, Sudan would be removed from the face of the earth if a tsunami hit the Ethiopian highlands or the dam collapsed,” he added.

He questioned the validity of studies undertaken by the company building the GERD and the Ethiopian government and wondered how the Ethiopian people’s money was being spent on building this mega-dam without conducting the proper geological studies.

Moreover, the team conducted another study on the hydrogen cycle, especially given the effects of El Niño, or the thermal difference between the oceans and the atmosphere that controls the river flow of the Blue Nile. The study concluded that a dry spell would hit the Ethiopian highlands at some point, when the rain will become scarce, and this will also affect the GERD’s storage capacities.

*A version of this article appears in print in the 4 November, 2021 edition of Al-Ahram Weekly

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