Drought Analysis in the Awash River Basin, Ethiopia

This study analyzes drought characteristics in the Awash River Basin of Ethiopia based on meteorological and hydrological variables. Standardized precipitation index is used for temporal and spatial analyses of meteorological drought and the theory of runs is used to define hydrological drought by considering streamflow as the drought indicator. Drought severity maps are generated using Arc View/GIS by summarizing the percentage of occurrence of droughts in areas within the study basin. Extreme drought category on 12-month time scale indicated that extreme events occur most frequently in the Upper and Middle Awash Basin. However, while considering the overall categories of drought, the most frequent droughts occurred in the Middle and Lower Awash Basin during the period of analysis. Similarly, results based on hydrological drought analysis shows that the severest drought events occurred in the Middle Awash Basin during May 1988 to June 1988 and April 1998 to May 1998. Analysis of the relationship between meteorological and hydrological drought indices in the basin shows that occurrence of hydrological drought event at Melka Sedi stream gauging station lags meteorological drought event in the Upper Awash on average by 7 months with a variation of 3 to 13 months.