Alterations in the hydrological cycle due to climate change are one of the key threats to the future accessibility of natural resources. This study used 12 GCM climate models from CMIP6 to evaluate future climate change scenarios by applying model performance measures and trend analysis in Kobo Valley, Ethiopia. The models were ranked based on their ability to analyze the historical datasets. The result of this study showed that the outputs of the FIO-ESM-2-0 CIMP6 model had a good overall ranking for both precipitation and temperature. After bias correction of the model-based projections with the observed data, the average annual precipitation in the average scenario (SSP2-4.5) decreased by 4.4% and 13% in 2054 and 2084, respectively. Similarly, in the worst-case scenario (SSP5-8.5), by the end of 2054 and 2084, decreases of 4% and 12.8%, respectively, were predicted. The average annual maximum temperature under the SSP2-4.5 scenario increased by 1.5 °C in 2054 and by 2.1 °C in 2084. The average annual maximum temperature under the worst-case (SSP5-8.5) scenario increased by 1.7 °C in 2054 and by 3.2 °C in 2084. In the middle scenario (SSP4.5), the average annual minimum temperature increased by 2.2 °C in 2054 and by 3 °C in 2084. The average annual minimum temperature under the worst-case (SSP5-8.5) scenario increased by 2.6 °C in 2054 and by 4.3 °C in 2084. The seasonal variability in precipitation in the studied valley will decrease in the winter and increase in the summer. A decrease in precipitation combined with an increase in temperature will strengthen the risk of drought events in the future.

Groundwater is a critical resource that underpins water security, but it is increasingly threatened by climate variability and growing anthropogenic pressures. In the Kobo Valley of Ethiopia, groundwater serves as the principal source of water for domestic and irrigation purposes, raising serious concerns about the sustainability of the aquifer. This study evaluates groundwater flow dynamics and provides insights for sustainable groundwater management in the region. A numerical groundwater flow model was developed using Visual MODFLOW Flex (MODFLOW 6), with key hydraulic parameters derived from pumping test data analyzed through Aquifer Test. Model simulations revealed seasonal groundwater-level fluctuations of up to 1.7 m along the eastern boundary and 1.4 m along the southern boundary. Scenario analysis indicated that a 50% reduction in pumping rates could effectively mitigate groundwater-level decline, limiting drawdown to 1.5 m during irrigation periods. These results demonstrate that the Kobo Valley aquifer is highly susceptible to over-extraction, emphasizing the importance of optimized pumping regimes, artificial recharge interventions, and continuous monitoring. The findings offer critical guidance for sustainable groundwater management and support the formulation of evidence-based water resource policies in Ethiopia.