FLOOD FREQUENCY ANALYSIS USING GUMBEL'S DISTRIBUTION METHOD: A CASE STUDY OF LUGBE TRADEMORE ESTATE FLOOD IN FCT ABUJA

Abstract

For the significance of checking the rate of flash flooding in Abuja and environs, Trademore estate where flash flood was experienced was picked with rainfall daily data of 1982 to 2022 and subsequent prediction, various probability distribution models were fitted to various rainfall in Lugbe part of Abuja in 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 the expected yearly maximum daily-rainfall 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 98 mm. The analysis of the Lugbe peak flow data suggests that the region is susceptible to extreme flood events. The data is skewed to the right, with a longer tail on the high end of the distribution, which means that extreme flood events are more likely to occur than would be expected if the data were normally distributed. The correlation between the peak flow and the return period is also strong and positive, which suggests that extreme flood events in Lugbe are becoming more frequent over time.