Assessment of Flood Frequency Using Maximum Flow Records for the Euphrates River, Iraq

A flood frequency analysis (FFA) on Euphrates River in Iraq has been carried out. Gumbel, generalized extreme value (GEV) and log person type III (LP3) probability distributions were employed for the simulating of flood flow using annual peak flow data from two gauging stations on Euphrates River. The first gauging station is Qaim station and recorded data for the period (1981-2018) was adopted the second gauging station is Hit station and its adopted records are for the period (1985-2018). The collected data was evaluated and tested for independency, stationary and homogeneity. The predicted flood flows of different return periods (Tr) i.e., 5, 10, 25, 50, 100 and 200 years are obtained and compared. The results show that the estimated flows of all the return periods does not exceed the current average carrying capacity of the river and this is due to the large number of dams built outside Iraq in Turkey and Syria. The estimated values for 100 and 200 years return period for Qaim gauge station are 2030 and 2250 m3/sec respectively while for Hit gauge station are 1480 and 1580 m3/sec respectively. Also, the results reveal that the river's flow can be satisfactorily expected by any one of the used probability distribution methods; however, the generalized extreme value (GEV) was found to be the better fitted as shown by the goodness of fit test