Mohammed Basher Manchester University’s scholar who has been studying the GERD for the past decade said that now no way to stop Ethiopia from filling the GERD until the water level reaches the top of the dam wall.
The scholar told BBC that the reservoir behind the dam will fill naturally during the Blue Nile’s rainy season, which has already begun and lasts until September justifying that more water is entering the dam site than the volume of water that can physically pass through the two open outlets in the dam wall.
As to the source, from the start of the process in 2011, the dam has been built around the Blue Nile as it continued to flow through the enormous building site.
Builders worked on the vast structures on either side of the river without any problem. In the middle, during the dry season, the river was diverted through culverts, or pipes, to allow that section to be built up.
The corporation indicated that in the first year, the GERD retained 4 billion cubic meters of water, taking it up to the height of the lowest point on the dam wall at that time.
On average, the total annual flow of the Blue Nile at the GERD site is 49bcm, but last year saw a 100-year record for the peak daily flow of water, indicating that only a small fraction of that annual water volume was held back.
This year the initial idea was to add a further 13.5bcm but satellite images analyzed recently by Sudan suggest that the dam wall has not been built as high as first planned, which would mean more water would pass through.
However, a note from Ethiopia’s water ministry to Sudan sent earlier this week indicated that the dam was still on course for holding back the same amount as originally planned.
In the dry season the reservoir will recede a bit, allowing for the dam wall to be built up and in the third year more water will be retained.
Ethiopia says it will take a further four to six years to fill up the reservoir to its maximum flood season capacity of 74bcm. At that point, the lake that will be created could stretch back some 250km (155 miles) upstream.
Concerning the interest of downstream countries the corporation reported that in years of normal, or above average, rainfall that should not be a problem, but Egypt is nervous about what might happen during a prolonged drought that could last several years.
The scholar argued that though the GERD could help regulate the flow of the Blue Nile and make Sudan less prone to floods, in the past 12 months Sudan’s rhetoric about the dam has moved from being broadly welcoming to being suspicious and belligerent.
The Ethiopian Herald July 9/2021
