Trend Analysis of Hydrological Drought for Selected Rivers in Iraq


The surface water in study area supports a range of uses such as water supply, irrigation and hydropower generation. Therefore, the assessment and analysis of the hydrological drought are important in the planning and management of the water resources. In this paper, hydrological drought was assessed using stream-flow drought index (SDI) based on observed mean monthly streamflow data collected from three selected gauging stations at Greater Zab River, Lesser Zab River and Khazir River located in the North-Eastern region of Iraq.Trend analysis of the hydrological drought was investigated using MannKendall non-parametric method to evaluate the significance of trends and Sen's slope method to determine the magnitude of the slope of trends for 47 years during the period 1965-2011. According to the SDI 3, 6 and 12-month time scales, the recorded drought was severe, and M-K method showed that the decreasing trends in the SDI values were statistically significant at α=0.05 mostly in the Greater Zab River and Lesser Zab River basins, increasing trendin SDI values is insignificant. This indicates that the hydrological drought is increasing over time at the study area.