Modeling lake-groundwater interactions under climatic and anthropogenic stressors in a mediterranean closed basin: Burdur Lake, Türkiye

Understanding lake–groundwater interactions is crucial for the sustainable management of fragile ecosystems, such as Burdur Lake, a Ramsar-listed closed-basin lake in the Mediterranean region of Türkiye. This study investigates the causes and consequences of long-term lake-level decline driven by both climatic and anthropogenic factors. A three-dimensional groundwater flow model was developed and calibrated using MODFLOW, incorporating the lake package under steady-state (1969, 2014) and transient (1969–1971, 2014–2016) conditions based on lake levels, groundwater observations, and a detailed conceptual lake budget. The calibrated model was extended to simulate future scenarios (2019–2064) using CORDEX regional climate projections (RCP 4.5 and RCP 8.5), assessing the effects of increased groundwater abstraction and streamflow regulation through reservoirs. Simulation results suggest that climate change alone may lead to a lake-level decline of 5–6 m, while combined with increased groundwater extraction, the decline may reach 7 m. However, restoring natural stream inflows by removing surface water reservoirs could result in a recovery of up to 3 m despite climate stress. The findings highlight the dominant role of surface water regulation in lake shrinkage and demonstrate the value of integrated modeling for guiding water management policies. This study provides a framework for assessing coupled lake–groundwater systems under multiple stressors in semi-arid, closed basin settings. • Simulated lake–groundwater interactions in a closed-basin Mediterranean lake system. • Integrated a conceptual lake water budget and the MODFLOW-Lake Package to assess historical and future lake level dynamics. • Demonstrated surface water regulation as the dominant driver of lake shrinkage. • Projected 5–7 m lake-level decline under climate and pumping scenarios. • Removal of upstream reservoirs may partially restore lake levels despite climate stress.