Characterization of hydrological drought conditions in Ethiopian Rift Valley lakes basin

Drought is the disastrous natural phenomena which causes social, economic, environmental and political crisis a given region due to water scarcity. This study presented the hydrological drought characteristics in the Ethiopian Rift Valley Lakes basin by using streamflow drought index (SDI). The streamflow data were collected from eighteen stations from Ministry of Water and Energy of Ethiopia (MoWE). SDI value computed by employing drought index calculator (DrinC) software and the trend of hydrological drought for three periods (SDI3, SDI6 and SDI12) were detected by applying the non-parametric Mann-Kendall trend test and Sen's slope method. The findings of the study indicate that there was no significant trend in seasonal basis whereas there was significant increasing and decreasing trends in biannual and annual basis in Kulfo, Tikurwuha, Kola and Katar stations. The most common severe hydrological drought periods in the basin were 1984, 1985, 1999 and 2002 and the most common extreme drought registered years were 1984, 1986, 1991 and 2002. The probability of drought occurrence varies from catchment to catchment and time scales used in the basin. Hence, this study may provide basic information about the hydrological condition which helps to develop better water adaptation and mitigation strategies in the basin.