Development of Intensity–Duration–Frequency (IDF) Curve for Extreme Flood Evaluation for Holeta Town, Ethiopia

Urban flooding is a challenging issue especially in rapidly developing countries like Ethiopia. The Intensity–Duration–Frequency (IDF) curves are commonly being used for flash flood and peak discharge estimation. The present study is carried out to establish the IDF curve for a rapidly growing Holeta town, Ethiopia. For this, rainfall records for 5 gauge stations and for 32 years (1986–2017) were collected from National Meteorology Agency of Ethiopia. After initial data checks, various distributing fittings (such as Log-Pearson III, General Extreme Value, Gumbel) have been used for estimation of intensity of rainfall for different time interval and return period. The effectiveness of the distributions was checked using three “Goodness of Fit” namely Kolmogorov Smirnov, Anderson Darling, Chi-Squared. The study found that Log-Pearson III type of distribution is having minimum goodness of fit error than others and thus, it has been ranked best among all. Also, two empirical IDF equations were derived for the study area using the IDF curves data. The developed IDF curve and empirical IDF equations can be utilized for extreme runoff and flash flood estimation for the data scare Holeta town and the illustrated framework can be followed for other towns of country by field engineers and practitioners.