Germeç et al. (2025) Modeling lake-groundwater interactions under climatic and anthropogenic stressors in a mediterranean closed basin: Burdur Lake, Türkiye

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-11-20
• Authors: Hatice Kılıç Germeç, Hasan Yazıcıgil
• DOI: 10.1016/j.ejrh.2025.102933

Research Groups

• Department of Geological Engineering, Middle East Technical University, Ankara, Türkiye

Short Summary

This study developed an integrated lake-groundwater model for Burdur Lake, Türkiye, to assess the long-term impacts of climate change and anthropogenic stressors. It found that surface water regulation by upstream reservoirs is the dominant driver of lake-level decline, with restoration of natural inflows potentially leading to a 3 meter recovery despite climate stress.

Objective

• Investigate the causes and consequences of long-term lake-level decline in Burdur Lake, Türkiye, driven by climatic and anthropogenic factors.
• Assess the combined effects of surface water control structures, groundwater abstraction, and projected climate change on the lake's hydrological balance.

Study Configuration

• Spatial Scale: Burdur Lake basin, southwestern Türkiye, covering an area of 1630 square kilometers (km²). The lake itself has a surface area of approximately 126 km² and a depth ranging from 59 meters (m) to 77 m.
• Temporal Scale: Historical analysis and model calibration for 1969–2018, with specific transient simulations for 1969–1971 and 2014–2016. Future projections span 46 years, from January 2019 to December 2064.

Methodology and Data

• Models used:
  • MODFLOW-2005 with Lake Package (three-dimensional groundwater flow model)
  • HEC-HMS (semi-distributed hydrological model for surface runoff)
• Data sources:
  • Observed lake levels (General Directorate of State Hydraulic Works - DSI staff gauges and limnigraph stations, 1969-2018)
  • Groundwater observations (DSI monitoring stations, 168 logged wells, 64 pumping tests)
  • Meteorological data (Burdur and Yazıköy stations: precipitation, temperature, evaporation, wind velocity, humidity)
  • CORDEX regional climate projections (RCP 4.5 and RCP 8.5 scenarios, MOHC-HadGEM2-ES GCM with RACMO22E and CCLM4–8–17 RCMs)
  • Bathymetric surveys (DSI)
  • Geological maps (General Directorate of Mineral Research and Exploration - MTA, 2010)
  • CORINE Land Cover data (European Environment Agency - EEA, 2020)
  • GCN250 dataset (Curve Number)
  • Population projections (DSI, 2016b)

Main Results

• Burdur Lake experienced a substantial long-term decline of approximately 17 m in elevation between 1969 and 2018, corresponding to a surface area loss of 95 km² and a volume reduction of 2.989 x 10^9 cubic meters (m³).
• Evaporation is the dominant loss mechanism in the lake's water balance, accounting for an average annual loss of 1.876 x 10^7 m³.
• A gradual shift in the dominant inflow source was identified: surface water inputs were predominant until 2005, after which groundwater inflow became predominant (averaging 6.74 x 10^6 m³/year).
• Future Scenario Projections (2019–2064):
  • Climate change alone (RCP 4.5 and RCP 8.5): Projected lake-level decline of approximately 4–5 m, corresponding to a volume loss of 4.94 x 10^8 m³ to 6.15 x 10^8 m³ and a surface area reduction of 11 km² to 14 km².
  • Climate change combined with increased groundwater abstraction: Total lake-level decline may reach 6–7 m, resulting in a cumulative volume loss of up to 7.33 x 10^8 m³ to 8.44 x 10^8 m³. Increased groundwater abstraction contributes approximately 1 m to this decline.
  • Climate change without stream reservoirs (restoring natural inflows): Lake levels could rise by up to 2–3 m compared to the baseline, restoring 7 km² to 16 km² of surface area and 2.21 x 10^8 m³ to 4.30 x 10^8 m³ of water volume.
• The predominant driver of Burdur Lake's decline is the reduction in natural surface water inflows caused by upstream reservoir construction and stream diversions.
• Model calibration achieved Normalized Root Mean Square Error (NRMSE) values of less than 4% for steady-state groundwater levels and less than 0.2% for transient lake levels, with a 95% prediction interval for simulated lake stages of ±0.43 m to ±0.49 m.
• The model was most sensitive to changes in horizontal hydraulic conductivity and recharge rates.

Contributions

• Presents the first integrated modeling framework for the Burdur basin, combining a conceptual lake water budget, numerical hydrological modeling (HEC-HMS), and numerical groundwater flow simulation (MODFLOW-Lake Package) to simulate dynamic lake-groundwater interactions.
• Quantifies the relative contributions of climate variability, surface water regulation, and groundwater abstraction to the long-term lake-level decline, providing a more realistic system-level understanding compared to studies focusing on individual stressors.
• Offers a process-based understanding and a transferable modeling framework for adaptive water resource management in semi-arid, closed-basin systems facing similar hydrological stresses.

Funding

This research was conducted as part of Hatice Kılıç Germec’s doctoral dissertation at Middle East Technical University. No specific external project funding or reference codes were mentioned.

Citation

@article{Germeç2025Modeling,
  author = {Germeç, Hatice Kılıç and Yazıcıgil, Hasan},
  title = {Modeling lake-groundwater interactions under climatic and anthropogenic stressors in a mediterranean closed basin: Burdur Lake, Türkiye},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.102933},
  url = {https://doi.org/10.1016/j.ejrh.2025.102933}
}