Developing Rainfall Intensity- Frequency- Duration Curves for Three Selected Sites in the Kurdistan Region, Iraq

The relationship of rainfall intensity frequency duration (IFD) is one of the key tools used considerably in water resources engineering, whether for planning, designing, managing, and operating projects for water resources or flood control and management projects. The purpose of this study is to develop IFD curves at a site location for three selected governorates, Kurdistan Region, Iraq. The current study covers rainfall data recorded over 30 years between 1991-2020 for three rainfall stations located within three governorates (i.e., Duhok, Erbil, and Sulaimaniya) in the Kurdistan Region, Iraq. The stationary IFD curves have been derived from fitting the three most commonly adopted probability distributions (namely, Generalized Extreme Value (GEV), Gumbel, and Log Pearson Type 3 (LPT3)) for the three selected rainfall stations. The fit of the rainfall data to the three selected distributions has been assessed by employing three goodness-of-fit tests (i.e., Kolmogorov-Smirnov (KS), Anderson-Darling (AD), and Chi-Square tests). The results indicated that the three selected distributions fit the rainfall data at the three significance levels (10%, 5%, and 1%) for all three stations. Overall, it has been discovered that at-site IFD curve data derived from the GEV distribution are generally higher than curves derived from the LPT3 and Gumbel distributions.