Projected future temperature, precipitation, and drought conditions in the Muger River sub-basin, central Ethiopia, using CMIP6 models

Projecting climate change at the watershed scale is essential for informing targeted adaptation and resilience strategies. This study assesses future changes in temperature, precipitation, and drought characteristics in the Muger River watershed, Ethiopia, using six CMIP6 general circulation models (GCMs) under SSP2-4.5 and SSP5-8.5 scenarios. Daily temperature and precipitation data were bias-corrected using the CMhyd tool with quantile mapping, showing strong agreement with observed records for the baseline period (1985–2014). Projections were evaluated for three time horizons: near-term (2021–2040), mid-century (2041–2070), and end-century (2071–2100). Results indicate substantial warming, with maximum and minimum temperatures projected to rise by up to + 3.2 °C and + 2.9 °C under SSP2-4.5, and + 6.4 °C and + 4.5 °C under SSP5-8.5, respectively, by 2100. Mean annual precipitation is projected to decline, ranging from 600–1254 mm yr⁻1 (SSP2-4.5) and 420–890 mm yr⁻1 (SSP5-8.5), compared to the historical range of 843–1723 mm yr⁻1. Drought analysis using the 12-month Standardized Precipitation Evapotranspiration Index (SPEI-12) reveals intensifying aridity, with more frequent and prolonged dry spells. Increases in consecutive dry days, extreme hot days (TX90p), and warm spell duration indicator (WSDI) further underscore the growing hydroclimatic stress. These findings offer critical insights to support regional climate risk assessment and adaptive water resource planning in the Muger watershed.