Spatiotemporal drought occurrences in the semi-closed Raya graben along the northern Ethiopian Rift Valley

Drought has become a major challenge in many Sub-Saharan Africa countries. This study aimed to investigate the precipitation trends and drought incidents in the semi-closed Raya graben in Ethiopia. Monthly precipitation records of nine meteorological stations for the years 1980-2016 were studied. The spatio-temporal drought conditions were analysed using Man-Kendall and Standardized Precipitation Index (SPI) techniques. A decreasing trend of precipitation was observed during the spring season (March-May) (p < 0.01). Many meteorological drought years were identified since 1980, occurring at varying temporal frequencies. Similarly, agricultural drought was occurring continuously for 1-5 years at an interval of five years. Our results also showed major hydrological droughts that persisted for 2-4 years occurring at an interval of five years. Almost all stations experienced an average intensity of moderate and above drought conditions during their agricultural and hydrological drought periods. Drought risk increased with the growing frequency of extreme drought events occurring every 14 months. Spatially, the southern and eastern parts were found to be more vulnerable to frequent, intense and longer drought conditions as compared to the western graben escarpment. Therefore, building adaptive capacity to climate change and extreme events is recommended to reduce the consequences of drought incidents in the Raya graben and northern Ethiopia.