Predicted effect of the grand Ethiopian renaissance dam on the Epilimnion temperature in the high Aswan dam reservoir.

The Nile River is a crucial geopolitical water stream. The construction of the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile poses significant challenges for downstream countries, including Egypt. The GERD will be the largest hydroelectric power plant in Africa and the seventh in the world. This led many researchers to investigate the impacts of the dam construction on water quantity, agriculture, power generation, and the environment. This study aims to investigate some of the environmental impacts of the operation of the GERD on the High Aswan Dam (HAD) reservoir. Water level fluctuations due to the operation of the GERD will directly affect the thermodynamics of the HAD reservoir. As a result, the vertical distribution of heat will be altered assuming the incoming solar radiation will remain the same. Studies indicate that the water level in the HAD reservoir will decline by 10–27 m, due to the filling of the reservoir upstream of the GERD over the next few years. To quantify the change in temperature, the heat content for the reservoir is calculated pre‐ and post‐dam operation. Moreover, a one‐dimensional simulation model, DYnamic REservoir Simulation Model (DYRESM), was used to simulate the change in thermal stratification of the HAD reservoir pre‐ and post‐GERD operation. Results showed that the epilimnion temperature is expected to increase during summer from an average of 31.9°C pre the GERD operation to 33.7°C post the GERD operation. Consequently, this is expected to affect the ecosystem in the reservoir. The findings of this study highlight the significant environmental impacts of the GERD on HAD reservoir. To mitigate these impacts and ensure the sustainable management of water resources in the Nile River basin, it is imperative to implement comprehensive policies and strategies. [ABSTRACT FROM AUTHOR]