The distribution fitting tool in MATLAB 2018a was adopted for modelling the annual maximum discharge series. In this study, the Gumbel's Extreme Value, Generalized Extreme Value (GEV), Log Normal 2 Parameter (LN2P) and Weibull distribution are used to fit the annual maximum series. The results indicated that GEV and LN2P are the best-performing distributions for the annual maximum series; however, we adopted LN2P for the flood frequency analysis due to parsimony considerations. The location (μ) and scale (σ) parameters for the LN2P distribution are 6.1 and 0.89, respectively. From the analysis, the computed magnitude of mean annual flood was 613.8 m³/s corresponding to a return period (T) of 2.78 years. Table 4 shows that three large flood events have been observed in the Aghanashini catchment in the years 2005, 2013, and 2014. The results of this study provide valuable information for designing flood protection measures. This information can be used to set design standards for flood walls or determine the height of riverbanks, depending on the specific location and the level of protection required.