Located on the River Abay (Nile), about 25Km from the border of Sudan, the Grand Ethiopian Renaissance Dam (G.E.R.D) is considered as one of the world’s impressive megaprojects, and after completion the largest hydropower dam in Africa.
It is a construction feat of Roller Compacted Concrete (RCC) with a length of 1,780 meters and height of 145 meters in the main dam, a rockfill concrete faced Saddle Dam1 of 5.2 Km length and 45 meters’ height, Waterways, two surface Powerhouses2 which encompasses thirteen francs’ turbines* coupled to synchronous generators3 each capable of generating 375MW/400MW at the left and right of the RCC dam, 500kV switchyard4, and Gated Spillway5 equipped with 6 radial gates. The Dam will create a 74 billion cubic meter (BCM) reservoir with a surface area of 1,874 km2 at the full supply level. The river bed is at an elevation of 500m ASL (Above Sea Level) making the dam’s maximum elevation at 645m ASL.
The Project objective is to enhance the hydro-power generation capacity of the country through developing a plant with a capacity of 5150 MW and average energy generation of 15,760 GWh per annum. The implementation of this project will ensure supply of renewable energy to the emerging agro and heavy industries of the country and will also secure the power trading between the neighboring countries and even the regional and continental interconnection. It is the nation’s pride to bring the project to reality.
The main dam is constructed in a gorge between two mountains with RCC and convention concrete (CVC) of total volume 10.2 million m3 where the configuration of the Dam is designed in such a way that the dry season flow passes through the diversion culverts and the rain season flow passes over the lower block of the dam with the left and right dam with a proper height not to flood the downstream structures. The lower blocks are structured to be constructed in four levels: 525, 560, 595, and 640 meters where the left and the right are elevated at least 10m to 15m above the lower blocks. As the lower blocks are raised, the diversion culvert which operates at the lower head and the bottom outlets that are designed to release water from the reservoir when the units are not operating cannot release the inflow of the rain season, it is inevitable to impound until the River spills over the lower block.
On the 22nd of July, 2020 G.E.R.D achieved one of its highly anticipated milestones achieving a height of 560m ASL on the lower block of the dam. It is an intermediate milestone for the impounding and start of the generation. This specific milestone was one that can be considered pride for the usage of the water and paves Ethiopia’s stride towards development. This is not only a matter of pride but also for the development of the dam, where this milestone speeds and facilitates the next milestones, the early generation, and the completion of the project. If this milestone has not been achieved, the early generation and the project completion would have been delayed at least by another year.
The G.E.R.D is configured to start the early generation with two units while the main dam is under construction. The early generation of the project is materialized taking advantage of the raised lower block of the central RCC dam to an elevation of 560m ASL. The two turbines are specially designed to operate at a lower head of a minimum of 60m. Following the dam construction sequence, it is expected to raise the lower block of the central dam to elevation 595m ASL. where the right and left RCC dam minimum elevation will be 606m ASL. Raising the lower block to this level will guarantee the start of the third unit, which is the second milestone of the project that guarantees to attain the final configuration in the consecutive year where the lower block will be raised to an elevation of 640m on the right side and to 645m on the left side of the dam respectively.
The project delay due to technical and non-performance from some of the contractors have disheartened the citizens in the realization of the project. On the other hand, the recent achievement of this milestone has raised the aspiration and hope of all the nation in the project as an affirmation of the country’s march towards successful economic growth.