Comparative Performance of the Halphen-A and Pearson Type III Distributions in Modeling Annual Maximum Discharges in Romania

This paper presents a frequency analysis of annual maximum discharges for two river basins in Romania, using the Halphen-A distribution, which belongs to the Halphen family of distributions (including Halphen-B and Halphen-Inverse types). The distribution parameters were estimated using two distinct methods: the Method of Moments and the Maximum Likelihood Method. The results are compared with the Pearson Type III distribution, which is considered the reference distribution in Romania for statistical hydrology studies. The performance of each model was evaluated through a multi-criteria approach, employing the Root Mean Square Error (RMSE) and the Mean Absolute Error (MAE). The analysis highlights the advantages and limitations of each distribution and estimation method, providing a detailed perspective on the applicability of Halphen distributions in flood frequency hydrology.