Modelling water budgets for groundwater management in Kobo Valley, Northern Ethiopian Rift Valley

Study Region: Kobo Valley aquifer, a semi-arid groundwater basin in the Northern Ethiopian.Study Focus: Groundwater depletion is critical in semi-arid regions where groundwater serves as the main water source. Management requires understanding groundwater budgets and how they respond to natural and human activities. We used a fully integrated hydrologic model (MODFLOW One-Water Hydrologic Flow Model, MF-OWHM2) to analyze water-budget components and their responses to surface-water availability, land-use change, and groundwater pumping. The simulations cover 1997–2023 and future scenarios up to 2050. New Hydrological Insights for the Region: The model simulation indicates that storage remained nearly stable until 2013; after that, increased agricultural water demand and climate variablity caused a loss of 0.2 km³ of storage by 2023. Scenario analysis outlines potential future trends: by 2050, the base case results in an additional loss of 0.5 km³, while a demand-increase scenario depletes 1.26 km³, with groundwater levels dropping by about 20–25 m and spring discharge drying up. Conversely, a reduced-pumping scenario limits losses to 0.67 km³, stabilizes groundwater levels, and maintains spring discharge, indicating a possible sustainable management approach. Water-budget analysis shows that increased pumping is balanced by increased recharge, reduced discharge and reduced storage, demonstrating the system's adaptive response to stress. We conclude that MF-OWHM2 is an effective tool for evaluating groundwater budgets and simulating climate and human impacts, providing insights for sustainable groundwater management.