ANALYSIS OF HISTORICAL AND PROJECTED METEOROLOGICAL DROUGHT CHARACTERISTICS OVER THE GENALE-DAWA RIVER BASIN, ETHIOPIA

Abstract

This study analyzes meteorological drought characteristics of historical and projected drought over the Genale Dawa river basin Ethiopia, employing the Standardized Precipitation and Evapotranspiration drought index over historical 1991–2020, while projected drought is analyzed, near-future 2041–2070 and far-future 2071–2100. Daily precipitation and temperature data were obtained from the Ethiopian Meteorology Institute for 27 meteorological stations. Projected drought is obtained from the CMIP6 model; the scenarios under SSP2-4.5 and SSP5-8.5 were selected after performance evaluation. The Mann-Kendall test was used to evaluate the drought’s temporal trends. The spatial and temporal patterns of drought characteristics were analyzed in all rainy seasons and annual time scales. The findings show that there have been wide variations such as drought magnitude, duration, frequency, and severity in spatiotemporal features throughout history and future periods. The year 1994 was noted to be the driest, with 85% of the stations experiencing drought in the base period. JJA was the driest of all seasons in 2009 followed by MAM in 2011 and SON in 1993. More seasonal drought frequency was evident during the SON season (146) over the historical period, which was followed by the JJA (138) and MAM (128). MAM rainy season was projected to see increased drought frequency in all scenarios except SSP5-8.5 near future. More stations showed wet conditions for the annual and September to November (SON) seasons. In the projection, Under SSP2-4.5 and SSP5-8.5 far future the trends show a propensity for dryness. The SPEI-3-month study results show both scenarios' average area coverage under drought will be lower than it was under the base period. However, the probabilities of the moderate scenario are higher than those of the worst scenario. In contrast, the 12-month SPEI indicates that when compared to the base period, the average area coverage under drought will rise in the moderate scenario and remain unchanged in the worst case. Collaborations with research organizations and non-governmental organizations are necessary to get resources for improving drought resilience and conducting further studies over the basin is recommended.