Evaluation of Best Fit Probability Distribution Models for the Prediction of Rainfall and Runoff Volume (Case Study Tagwai Dam, Minna-Nigeria)

Abstract

For the significance of monitoring hydrometric data and subsequent prediction, various probability distribution models were fitted to various rainfall and runoff for the Tagwai dam site in Minna, Niger State, Nigeria. This is to evaluate the model that is best suitable for the prediction of their values and subsequently using the best model to predict for both the expected yearly maximum daily-rainfall and yearly maximum daily-runoff at some specific return periods. Many models were evaluated for the rainfall runoff and the best model was selected based on the statistical goodness of the fit test. The Normal distribution model was found most appropriate for the prediction of yearly maximum daily-rainfall of 131.21mm and the Log-Gumbel distribution model was the most appropriate for the prediction of yearly maximum daily-runoff of 1124.73 m3/s. Based on this, the Normal distribution and the Log-Gumbel distribution are good for the estimation of rainfall and as well as runoff volume respectively for the Tagwai dam site. Hence, the establishment of these models has made the prediction of both the rainfall and runoff volume for Tagwai dam possible.