Hamid Reza Asgari - Department of Civil Engineering, Shirvan Branch, Islamic Azad University, Shirvan, Iran
Ali Ghiami Bajgirani - Assistant Professor, Department of Civil Engineering, The Institute of Higher Education of Eqbal Lahoori, Mashhad, Iran
Shokoufeh Pourshahabi - Lecturer, Department of Civil Engineering, Eghbal Lahoori Institute of Higher Education, Mashhad, Iran
Bahare Asgari - Student of Civil Engineering Department, Khavaran Institute of Higher Education, Mashhad, Iran

The Design of water structures requires an in-depth understanding of extreme events. Analysis of the extreme events includes considering the minimum or maximum values that the maximum amount of rainfall expected during a specific time period is an example of it. The partial duration series (PDS) deals with the selection of over-threshold values. In this paper, for extreme values of rainfall, a threshold level is selected which leads to the best fitness between the PDS extracted and generalized Pareto distribution (GPD). The daily rainfall data for 44 years of Mashhad synoptic station is used in this paper. The comparison between the right tail of the GPD curve and probability distribution for observed events shows that the threshold of 17 millimeters is a better option for extracting of PDS

Partial duration Series, Generalized Pareto distribution, Rainfall threshold