Quantifying Meteorological Drought Severity for the Watersheds in Euphrates River Basin, Central Euphrates District, Iraq

Zahraa H. Al-Moussawi; Imad H.  Obead

doi:10.46717/igj.57.1D.18ms-2024-4-28

Authors

Zahraa H. Al-Moussawi Department of Civil Engineering, College of Engineering, University of Babylon, Babylon, Iraq
Imad H. Obead Department of Civil Engineering, College of Engineering, University of Babylon, Babylon, Iraq

DOI:

https://doi.org/10.46717/igj.57.1D.18ms-2024-4-28

Abstract

Drought is a major natural extreme event that can cause significant damage to water
resources. This study investigated the implications of drought for Watersheds in Euphrates
River basin in Iraq which includes Hilla, Karbala, Najaf, Diwaniyah, and Najaf.. It was
found that had an adverse impact on the study region. Among the most often used drought
assessment indices globally are the Standard Precipitation Index (SPI) and its version, the
Standard Precipitation and Evapotranspiration Index (SPEI). The study evaluated several
probability distribution functions to model rainfall and water balance in Iraq. The
Kolmogorov–Smirnov (K–S) test and the Anderson–Darling (A–D) test were used to test
the goodness-of-fit for rainfall and water balance. The log-normal distribution was found to
be the best fit for rainfall at approximately 40% of the stations considered, while the
generalized logistic distribution (genlog) was the best fit for water balance at approximately
80% of the stations considered. The study also found that the extreme droughts in Samwah
in 2012 and Diwiniyah in 1999 had the highest severity values of -2.8957 in SPI-12 and
SPEI-12, respectively.