<p>The Senonian aquifer of the Complex Terminal in the Kebili region, southern Tunisia, is a vital but overexploited groundwater resource, mainly used for agricultural and domestic purposes, with limited abstraction for industry and tourism. Overabstraction, driven by increasing demand and extensive unregulated drilling, has led to severe piezometric declines and water quality degradation. Additionally, climate change projections indicate a temperature rise of 2.3–3.8&#xa0;°C and a precipitation decrease of 14% by 2050, further threatening groundwater availability. This study aims to assess the aquifer’s resilience under intensive exploitation and climate change. A combined approach is employed, integrating environmental isotopes (²H, ¹⁸O, and ¹⁴C) to investigate recharge sources and flow rates, and employing numerical modeling using FEFLOW to simulate hydrodynamic behavior under different stress scenarios. Scenario analysis shows that increasing withdrawals of 60% by 2050 would deplete 76% of groundwater resources, whereas a 30% reduction could slow, but not prevent, depletion due to the aquifer’s limited recharge. Moreover, climate-induced increases in potential evapotranspiration (ETP) (from 8.29 to 9.08 mm/day) and crop evapotranspiration (ETc) (from 9.95 to 10.89 mm/day) will contribute to a 10–15% rise in abstraction rates, further depleting groundwater resources. The transition toward an unconfined state will reduce the aquifer’s hydraulic conductivity and storage capacity, intensifying salinization hazards. To enhance aquifer resilience, urgent management interventions are needed, including stricter regulation of groundwater abstraction, improved irrigation efficiency, and development of alternative water resources. These measures are crucial to mitigating irreversible depletion and ensuring long-term water security in the Kebili region.</p>