In a unilateral move, Ethiopia started constructing the Grand Ethiopian renaissance Dam (GERD) across the Blue Nile Early 2011, few weeks after the Egyptian revolution of January 2011. After the Ethiopian announcement of the dam construction, a debate was opened between the three Eastern Nile countries around the impacts of GERD that would control 1.4 times the mean annual flow of the Blue Nile. Egypt has been very sensitive toward this dam because of its huge size and its potential negative impacts on the country. Given that it is highly depending on Nile water (dependency ratio 97%). Blue Nile basin contributes about 60% of the Nile water that arrives to Egypt. An agreement between the three countries to arrive at dam filling and operation policies without threatening downstream users’ water security, economy and stability, is reached in March 2015 namely, "Declaration of Principles".
Several studies had investigated GERD filling and/or operation using simulation techniques, yet the optimum operation policy of GERD is not investigated. This study develops a nonlinear optimization model for GERD operation using natural historical inflow series (1912-2011), with the objective of maximizing the produced firm energy. The model aims to find the optimum firm hydropower production along with the resultant impacts on the Blue Nile flow. Several formulations of the objective functions were investigated, but the most stable GERD firm energy were obtained when minimizing the sum of squared deviation from the firm hydropower production.
Due to the nonlinearity of the objective functions and several constraints, extended Lingo 16.0 algorithm was used to solve the nonlinear optimization model. The results of model applications showed that GERD average hydropower production is about 14,500 GWH/year. The firm energy is 12,800 GWH/year that represents 24% of dam installed hydropower capacity. It is found that the GERD will cause a permanent reduction in the Blue Nile Flow on the order of 5%. But more severely, it is found that the GERD will cause an n extension (2-3 times) of the drought periods for Egypt and Sudan as compared to the case without GERD. Different operational strategies of the GERD were tried to evaluate potential regional management alternatives for the river basin, and an operational strategy is selected to reduce the potential negative downstream impacts without significant reduction of produced firm energy from the dam.
This was presented as a poster