Kartal et al. (2025) Projected intensification of drought in the Kızılırmak Basin, Türkiye, under CMIP6 climate scenarios: comparative evaluation of multi-model and multi-index approaches

Identification

• Journal: Meteorology and Atmospheric Physics
• Year: 2025
• Date: 2025-11-04
• Authors: Veysi Kartal, Emre Topçu, Zeyneb Kılıç
• DOI: 10.1007/s00703-025-01097-5

Research Groups

• Civil Engineering Department, Engineering Faculty, Siirt University, Siirt, Türkiye
• Civil Engineering Department, Faculty of Engineering and Architecture, Kafkas University, Kars, Türkiye
• Civil Engineering Department, Faculty of Engineering, Adıyaman University, Adıyaman, Türkiye

Short Summary

This study projects the future evolution of drought characteristics in the Kızılırmak Basin, Türkiye, under four CMIP6 Global Climate Models (SSP5-8.5 scenario) and three meteorological drought indices. The findings indicate a progressive intensification of droughts, with a higher frequency of extreme drought events, particularly in the mid- and far-future periods, emphasizing the critical role of temperature-driven evapotranspiration in exacerbating drought severity.

Objective

• To project the future evolution of drought characteristics (duration, frequency, severity) in the Kızılırmak Basin, Türkiye, under CMIP6 climate scenarios (SSP5-8.5).
• To compare precipitation-based (SPI, CZI) versus combined precipitation-and-temperature-based (SPEI) drought indicators.
• To quantify shifts in multiple drought metrics across near-future (2025–2048), mid-future (2049–2074), and far-future (2075–2100) periods.
• To highlight inter-model variations in drought projections to inform water resource planning.

Study Configuration

• Spatial Scale: Kızılırmak Basin, Türkiye (total area of 78,646 square kilometers), with specific analysis for Çankırı and Kayseri stations.
• Temporal Scale:
  • Historical (baseline) drought conditions from observed station data.
  • Future projections for three periods: near-future (2025–2048), mid-future (2049–2074), and far-future (2075–2100).
  • Drought indices calculated at monthly (1-month), seasonal (3-month), and annual (12-month) timescales.

Methodology and Data

• Models used: Four CMIP6 Global Climate Models (GCMs): ACCESS-CM2, EC-Earth3-Veg, GFDL-ESM4, and HadGEM3-GC31-MM, under the high-emission SSP5-8.5 scenario.
• Data sources:
  • Observed station data (precipitation and average temperature) for Çankırı and Kayseri.
  • CMIP6 model outputs for precipitation (p) and average temperature (Tave).
  • Meteorological drought indices: Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), and China Z Index (CZI).
  • Performance evaluation metrics: Root Mean Square Error (RMSE), Determination of Coefficient (R²), Nash–Sutcliffe efficiency (NSE), Mean Absolute Error (MAE), and Index of Agreement (IO).

Main Results

• A progressive intensification of droughts is projected, with a higher frequency of extreme drought events, particularly in the mid- and far-future periods (2049–2100).
• SPI-based analyses consistently project stronger drought severity compared to SPEI and CZI, but SPEI-based drought detection becomes more critical toward the late 21st century due to increasing temperature and evapotranspiration.
• Kayseri generally experiences stronger drought intensities than Çankırı across all future periods.
  • Average maximum drought intensity (monthly indices, all models):
    • Near-future: Çankırı -2.16, Kayseri -2.35
    • Mid-future: Çankırı -2.31, Kayseri -2.37
    • Far-future: Çankırı -2.32, Kayseri -2.37
• Short-duration droughts (1-month SPI) show a higher count of extreme drought events, indicating rapid onset moisture deficits.
• Longer-duration deficits (12-month SPI/SPEI) become increasingly intense by the late 21st century, posing risks for long-term water storage.
• The GFDL-ESM4 model often projects the most severe drought outcomes, with maximum SPI-1 anomalies occasionally dipping below -3.8 in the far-future for Çankırı.

Contributions

• Provides a comprehensive multi-model and multi-index assessment of future drought characteristics in the Kızılırmak Basin, a critical region in Türkiye.
• Offers a nuanced understanding of drought vulnerability by comparing precipitation-only and combined precipitation-and-temperature-based indicators, highlighting the increasing importance of temperature in future drought assessments.
• Quantifies shifts in multiple drought metrics (frequency, duration, severity) across distinct future intervals, providing detailed insights for proactive water resource planning.
• Serves as a basis for developing targeted early warning strategies and adaptive water-resource management plans to mitigate intensifying climate stress in the basin.

Funding

No funding.

Citation

@article{Kartal2025Projected,
  author = {Kartal, Veysi and Topçu, Emre and Kılıç, Zeyneb},
  title = {Projected intensification of drought in the Kızılırmak Basin, Türkiye, under CMIP6 climate scenarios: comparative evaluation of multi-model and multi-index approaches},
  journal = {Meteorology and Atmospheric Physics},
  year = {2025},
  doi = {10.1007/s00703-025-01097-5},
  url = {https://doi.org/10.1007/s00703-025-01097-5}
}