Assessment of hydrological drought characteristics in diverse climatic zones of Genale Dawa River Basin: a multimetric approach

Abstract

ABSTRACT Graph Showing drought occurrence, Duration and Severity in different sub basin of Genale Dawa River Basin. Hydrological drought is a natural disaster that significantly affects agriculture and the livelihood of pastoralists in developing countries like Ethiopia. This study aims to examine the hydrological drought characteristics in diverse climatic zones of Genale Dawa Basin in terms of duration, severity, and return periods using a multimetric approach. The study used the modified surface water supply index and streamflow drought index to characterize droughts in nine flow stations in the basin. The two indices’ results showed that the 2000s and the second half of the 2010s were the most moderate-to-extreme drought years at 3-, 6-, and 12-month time scales in the study area. Drought duration analysis in the study area indicates more than 50% dry periods on average and 58.33% dry months in the Dawa sub-basin. The basin has experienced severe droughts with an estimated 4.3 severity level, which increases toward the lowland regions up to 5 levels. The climate zones most vulnerable to hydrological drought are warm temperate climate (Cws), followed by hot arid climate (Bwh) in the southwestern to eastern region of the basin. This result is quite alarming and demands immediate water management plans to conserve water resources in the study area.