Integrated assessment of meteorological, hydrological and agricultural drought in Abaya Chamo sub Basin, Ethiopia

The Abaya Chamo sub basin is susceptible to drought of moderate to severe intensity, which significantly impacts the sub basin's agricultural production and local community life. We investigate drought characteristics in the Abaya Chamo sub basin using data from 1981 to 2021 and a variety of drought indices, including the Standardized Precipitation Evapotranspiration Index (SPEI) to identify meteorological drought, the Standardized Stream flow Index to assess hydrological drought, and the Standardized Soil Moisture Index (SSMI) to evaluate agricultural drought. The results indicate that all indices captured historical drought episodes, with only minor variations. Additionally, the findings show that the proportion of dry months exceeded that of rainy months between 1981 and 2021, showing that aridity increased during this period. We also identify drought trends that vary by watershed and by drought type. This study reveals that the sub basin experienced the maximum drought intensity, as computed using the SPEI, SSI, and SSMI, with index values of -2.5, -2.8, and - 2.4, respectively. The Gelana catchment experienced the most severe drought, while the Bilate catchment faced less severe drought. Overall, the study indicates severe to moderate drought of substantial magnitude that varied across the sub basin. These findings will guide drought planning and management in the Abaya Chamo sub basin and raise stakeholders' awareness of how precipitation, runoff, and soil moisture can be used to describe drought. Consequently, the study suggests that stakeholders and policymakers implement early warning systems and adaptive measures for water resource management, and develop comprehensive drought risk management plans to improve regional food security.