Fitting Probability Distribution Functions to Reservoir Inflow at Hydropower Dams in Nigeria

Some methods of probability distribution analysis were evaluated for the prediction of reservoir inflow at hydropower dams in Nigeria: The hydropower dams include Kainji, Shiroro and Jebba. The reservoir inflow data were subjected to probability distribution analysis including Gumbel, normal, log- Pearson type III, and log-normal. The selection of the appropriate probability distribution model for each hydropower dam was based on goodness of fit tests. The values of goodness of fit for each of the hydropower dams are r = 0.95, R super(2) = 0.96 for Kanji, r = 1.00, R super(2) = 0.99 for Shiroro, and r = 0.88, R super(2) = 0.96 for Jebba. For the Kanji and Shiroro hydropower dams the log-Pearson type III model gave the best fit, while for Jebba the best fit model was log-normal. These probability distribution models can be used to predict the near future reservoir inflow at the three hydropower dams.