Extreme Value Modelling Of The Water Levels Of The Akosombo Dam

ABSTRACT The Akosombo dam is Ghana‟s main source of energy. Considering the current increase in the demand for electricity in the country, where an increase in demand implies more pressure on the dam, it is therefore very important to investigate the tail behaviour of the water levels of the dam. This is necessary because the level of water in the dam determines the amount of electricity generated. The study investigated this problem using Univariate Extreme Value Theory. Both the Generalized Extreme Value distribution and the Generalized Pareto distribution were fitted to the Akosombo data. The Generalized Extreme Value distribution performed better than the Generalized Pareto distribution. Maximum likelihood estimation method was employed in the estimation of the model parameters. The study indicated that the water levels cannot fall below 226.00ft., which is the critical water level of the Akosombo dam. However, there is evidence of the dam attaining water levels below the minimum head operation level. We therefore recommended that, other forms of power generation should be explored to reduce the dependence on the Akosombo dam due to the fact that the dam can attain water levels below the minimum head operation. We also recommended that to prevent flooding during periods of excess water and abundant inflow, the high of the reservoir should be extended to retain the excess water which is spilled out