Study the sever rains effect on the estimation return period for selected areas of Iraq

Rainfall is one of the temporally changing climatic elements of the regions themselves, where they are few for a certain period or severe. Therefore, scientists and researchers interested in studying its prediction. In this study Gumbel method (one of the widely used for extreme values in meteorological studies for predictions) is used to calculate the return period of 24-hours maximum rainfall for selected areas of Iraq, period (2007-2019). The results show for the all period of study where (R5,R10,R25) are prediction period (5,10,25)years Consecutively, maximum rainfall during 24-h for the next five years, not to exceed (65 mm) in all stations while next 25 years the most sever in all stations reach (100 mm) in Baghdad. To determine the effect of severe rainfall values on the prediction of the return period, The same calculations were made without very severe rainfall values for each station resented Ra, Return Period without very tow severe rainfall values resented Rb. By comparing the results of the three cases (R,Ra and Rb) The stations (Baghdad, Khanaqin, Karbala, Nasiryia, Kirkuk and Mosul) R5 decries about (10-5)mm and Rb decries (20-4)mm. while stations (Rutba, Hay, Basra and Diwaniya ) R5 decries about (5-1)mm and Rb decries (10-2)mm. Return period R10 and R25 for 24-hours maximum rainfall decreases (20) mm, but not at all stations.