Şimşek et al. (2026) Investigating drought trends with new and traditional drought indices using innovative trend analysis (ITA): A case of Seyhan, Ceyhan, and Asi River Basins, Türkiye

Identification

• Journal: Environmental Earth Sciences
• Year: 2026
• Date: 2026-01-20
• Authors: Serin Değerli Şimşek, Evren Turhan
• DOI: 10.1007/s12665-025-12802-3

Research Groups

• Department of Civil Engineering, Adana Alparslan Türkeş Science and Technology University, Adana, Türkiye

Short Summary

This study investigated historical drought trends in Türkiye's Seyhan, Ceyhan, and Asi River basins using four drought indices (SPI, RDI, DPI, NDI) and Innovative Trend Analysis (ITA) over 52 years, revealing significant spatial and temporal variability in drought conditions and highlighting the importance of multi-index approaches for accurate assessment.

Objective

• To investigate historical drought trends in Türkiye's Seyhan, Ceyhan, and Asi River basins using a harmonized, multi-index evaluation (SPI, RDI, DPI, NDI) and Innovative Trend Analysis (ITA).
• To provide region-specific evidence for spatial-temporal drought patterns and establish a reproducible baseline for drought monitoring and water resource planning in southern Türkiye.
• To compare the sensitivities and effectiveness of traditional and newly developed drought indices (DPI, NDI) in a Mediterranean climate setting.

Study Configuration

• Spatial Scale: Seyhan, Ceyhan, and Asi River basins in southeastern Türkiye, utilizing data from 13 meteorological stations.
• Temporal Scale: 52-year period, from 1970 to 2021, divided into three sub-periods for detailed trend evaluation.

Methodology and Data

• Models used:
  • Standardized Precipitation Index (SPI)
  • Reconnaissance Drought Index (RDI)
  • Discrepancy Precipitation Index (DPI)
  • New Drought Index (NDI)
  • Innovative Trend Analysis (ITA)
• Data sources:
  • Meteorological data (precipitation, temperature, potential evapotranspiration) from 13 stations provided by the Turkish State Meteorological Service (MGM).

Main Results

• SPI and RDI showed strong correlation due to their reliance on precipitation data, consistently identifying the same extreme wet (1976, 1981, 1987, 1988, 1997, 2009) and dry (1989, 1990, 1993, 2013, 2017, 2020) years.
• NDI, incorporating temperature data, exhibited broader sensitivity and greater intensity in detecting extreme wet and drought periods, showing widespread negative trends in the third period (post-2000) across most stations.
• DPI was highly responsive to drought conditions, predominantly marking dry periods, but showed lower internal consistency and minimal trends in ITA, suggesting less responsiveness to climate fluctuations.
• ITA revealed significant spatial variability in trends: NDI showed declines across most stations, RDI declined in Karaisalı and Kahramanmaraş, while Karataş consistently showed increasing wet trends across indices.
• Precipitation variability was identified as the primary driver of drought classifications, whereas temperature and potential evapotranspiration (PET) displayed relative stability in their trends.

Contributions

• Provided a harmonized, multi-index evaluation of drought conditions on a common dataset for the Seyhan, Ceyhan, and Asi River basins in southern Türkiye.
• Applied Innovative Trend Analysis (ITA) to drought indices, offering a nuanced diagnosis of basin-scale variability and localized shifts.
• Contributed region-specific evidence of spatial-temporal drought patterns, establishing a reproducible baseline for drought monitoring and water resource planning.
• Emphasized the utility and practical application of newly developed indices (DPI and NDI) alongside established ones in a Mediterranean climate, highlighting their index-specific sensitivities.
• Underscored the critical need for employing multiple drought indices to accurately capture complex climatic dynamics and inform future drought management strategies.

Funding

• Open access funding provided by the Scientific and Technological Research Council of Türkiye (TÜBİTAK).

Citation

@article{Şimşek2026Investigating,
  author = {Şimşek, Serin Değerli and Turhan, Evren},
  title = {Investigating drought trends with new and traditional drought indices using innovative trend analysis (ITA): A case of Seyhan, Ceyhan, and Asi River Basins, Türkiye},
  journal = {Environmental Earth Sciences},
  year = {2026},
  doi = {10.1007/s12665-025-12802-3},
  url = {https://doi.org/10.1007/s12665-025-12802-3}
}