Spatiotemporal analysis of CMIP6-based climate extremes and their implications for sustainable watershed management in the Gidabo watershed, Ethiopia

Climate extremes have profound implications for watershed sustainability, influencing hydrological processes and soil erosion. This study examines spatiotemporal trends of precipitation and temperature extremes in Ethiopia's Gidabo watershed under the SSP2-4.5 and SSP5-8.5 scenarios, using an ensemble of six Global climate models (GCMs). The primary aim is to assess future climate extremes and their implications for watershed management. The GCM data were bias-corrected using the Distribution Mapping (DM) method in the CMhyd software, using daily precipitation and temperature data from six meteorological stations. The Mann-Kendall (MK) trend analysis and the Theil-Sen Estimator were applied to analyze extreme climate indices, while ArcGIS was used for spatial visualization. The results indicate that precipitation extremes (Rx1day, Rx5day, PRCPTOT, R95pTOT, and R99pTOT) decrease in the near future but increase in the mid-term, particularly in the northeastern part of the watershed. Dry spells decline, while wet spells increase, suggesting a wetter climate. Heavy rainfall days (R10mm and R20mm) decrease initially but rise in the mid-future. Temperature extremes (TXx, TXn, TNx, TNn) increase significantly, with the most pronounced warming under the SSP5-8.5. Furthermore, warm spells intensify, while cold spells become less frequent. These changes have critical implications for watershed management. The eastern and northeastern regions face higher flood and erosion risks, requiring soil conservation and flood mitigation measures, whereas the southwestern zones demand drought-resistant agriculture and water-efficient strategies. Proactive measures, including erosion control, land-use planning, and climate-resilient farming, are essential to mitigate climate change impacts and ensure sustainable water and soil resource management in the Gidabo watershed.