Çakur et al. (2026) Söylemez Barajı Havzasında Meteorolojik ve Hidrolojik Kuraklığın Çok Ölçekli SPI ve SSFI Analizleri ve İndisler Arasındaki İlişki

Identification

• Journal: Osmaniye Korkut Ata Üniversitesi Fen Bilimleri Enstitüsü Dergisi
• Year: 2026
• Date: 2026-01-13
• Authors: Bünyamin Çakur, İlteriş Taşkolu, Reşat ACAR, Burak Çırağ
• DOI: 10.47495/okufbed.1776078

Research Groups

• Atatürk University, Faculty of Engineering, Department of Civil Engineering, Erzurum, Turkey
• Istanbul Esenyurt University, Vocational School, Construction Technology Program, Istanbul, Turkey

Short Summary

This study analyzed meteorological and hydrological drought characteristics in the Söylemez Dam Basin (Aras Basin, Turkey) from 1992-2023 using multi-scale Standardized Precipitation Index (SPI) and Standardized Streamflow Index (SSFI). It found statistically significant decreasing trends in both precipitation and runoff, with strong correlations between long-term meteorological and hydrological droughts, highlighting a critical need for water management strategies.

Objective

• To determine the meteorological and hydrological drought characteristics of the Söylemez Dam Basin using SPI and SSFI across multiple time scales (1, 3, 6, 9, 12, and 24 months).
• To investigate statistically significant trends and their direction in precipitation and runoff data using the Mann-Kendall test.
• To evaluate the relationship and interaction between meteorological and hydrological droughts within the basin.

Study Configuration

• Spatial Scale: Söylemez Dam Basin, a sub-basin of the Aras Basin, located within Erzurum Province, Turkey. The dam's rainfall area is 2,700 square kilometers.
• Temporal Scale: 1992-2023 (32 years) for both precipitation and runoff data.

Methodology and Data

• Models used:
  • Standardized Precipitation Index (SPI)
  • Standardized Streamflow Index (SSFI)
  • Mann-Kendall trend test
  • Sen's slope estimator
  • Thiessen Polygon method (for spatial distribution of rainfall)
  • Gamma distribution (for SPI and SSFI calculations)
• Data sources:
  • Precipitation data: Monthly total average precipitation from Erzurum, Horasan, Hınıs, and Bingöl meteorology observation stations, provided by the State Meteorology 12th Regional Directorate.
  • Runoff data: Monthly total inflow data for Söylemez Dam (D24A096 stream gauge station), provided by the State Hydraulic Works 8th Regional Directorate.

Main Results

• Mann-Kendall trend analysis revealed statistically significant decreasing trends in both precipitation and runoff data for the 1992-2023 period.
• Meteorological Drought (SPI): The most severe and longest meteorological drought period was observed from late 2012 to early 2016 across all SPI time scales. Other notable drought periods included 1998-1999 and 2007-2008, with a new significant drought trend starting in 2020-2022.
• Hydrological Drought (SSFI): The most intense and prolonged hydrological drought period was identified from 2013 to 2015 across all SSFI time scales. Other periods of hydrological drought were 2000-2002 and 2020-2022.
• Relationship between SPI and SSFI:
  • Correlation (r²) between SPI and SSFI generally increased with longer time scales.
  • Short-term SPI and SSFI showed low correlation, indicating that immediate precipitation deficits do not instantly translate to streamflow deficits.
  • Strong positive correlations were observed for longer time scales (e.g., r² values up to 0.85973 between SPI-24 and SSFI-24), demonstrating that long-term precipitation deficits have direct and significant effects on runoff.
  • A lag effect of approximately 3 to 6 months was identified, where meteorological drought impacts on hydrological systems manifest with a delay due to basin storage capacity.

Contributions

This study provides an original multi-scale analysis of the interaction between meteorological (SPI) and hydrological (SSFI) droughts in the Söylemez Dam Basin using recent data (1992-2023). It quantifies the decreasing trends in precipitation and runoff and highlights the significant lag effect between meteorological and hydrological drought occurrences, offering crucial insights for future water management and drought resilience planning in the region.

Funding

This article was prepared as part of Bünyamin ÇAKUR's Master's thesis. The authors acknowledge Atatürk University Institute of Science.

Citation

@article{Çakur2026Söylemez,
  author = {Çakur, Bünyamin and Taşkolu, İlteriş and ACAR, Reşat and Çırağ, Burak},
  title = {Söylemez Barajı Havzasında Meteorolojik ve Hidrolojik Kuraklığın Çok Ölçekli SPI ve SSFI Analizleri ve İndisler Arasındaki İlişki},
  journal = {Osmaniye Korkut Ata Üniversitesi Fen Bilimleri Enstitüsü Dergisi},
  year = {2026},
  doi = {10.47495/okufbed.1776078},
  url = {https://doi.org/10.47495/okufbed.1776078}
}