Hydro-meteorological drought in Addis Ababa: A characterization study

Abstract

Drought is one of the most natural hazards that cause damage to ecosystems, agricultural production, and water resources. This study has analyzed seasonal and annual rainfall trends using monthly data series of 33 years (1983–2015) in Addis Ababa city over three stations namely; Sendafa, Bole, and Observation. Here, we examined the occurrence of historical drought trends in the study jurisdiction. The Reconnaissance Drought Index (RDI) and the Standardized Precipitation Index (SPI) were employed to find long-term drought trends as well as to examine the occurrence of drought history at a longer duration. The analysis indicated that severe drought conditions were observed for SPI and RDI indices in the year 2013 for Bole station, while medium droughts were recorded for the years 1991 and 2002 for all stations. Similarly, the RDI indices for 1996 was recorded as severe drought for the Observatory station. On the other hand, higher variability (coefficient of variation) of rainfall during winter seasons were 95.8%, 95.9%, and 77.9% for Sendafa, Bole, and Observatory stations respectively. However, the lower coefficient of variation during annual rainfall was 15.59% for Sendafa, 14.38% for Bole, and 13.98% for the Observatory station. Furthermore, the drought severity classification for the long-term drought analysis of annual precipitation shows that 3% of severe drought, 12% of moderate drought, and 85% of the normal condition were recorded in Bole station. The severe and moderate drought indices due to the reduction of rainfall, temperature change, and other factors can cause a shortage of urban water supply. Thus, the results of this study will help the water sector professionals in forecasting weather variations and for better management of urban water resources.