Deger (2026) Exploring Monthly, Seasonal and Annual Spatio-Temporal Variability of Temperature and Precipitation Series by Classical and Innovative Techniques

Identification

• Journal: Water Resources Management
• Year: 2026
• Date: 2026-03-01
• Authors: Ibrahim Halil Deger
• DOI: 10.1007/s11269-026-04498-2

Research Groups

• Civil Engineering Department, Hasan Kalyoncu University, Gaziantep, Turkey

Short Summary

This study comprehensively analyzed the spatio-temporal variability and trends of temperature and precipitation across 12 stations in Southeastern Anatolia, Türkiye, revealing a dominant significant increasing trend in temperature and a prevalence of non-significant decreasing trends in precipitation.

Objective

• To comprehensively analyze the spatio-temporal variability and trends of monthly, seasonal, and annual temperature and precipitation series across 12 stations in Southeastern Anatolia, Türkiye, using both classical (Mann-Kendall, Spearman's Rho, Wilcoxon, Sen's Slope) and innovative (Innovative Trend Analysis Significance Test, Graphical Innovative Trend Analysis) statistical techniques.

Study Configuration

• Spatial Scale: Southeastern Anatolia Region, Türkiye, covering 12 meteorological stations across provinces including Siirt, Gaziantep, Kilis, Adıyaman, Şanlıurfa, Mardin, Diyarbakır, Batman, and Şırnak. The region is located between 38° 6′ 22′′ North and 41° 19′ 43′′ East.
• Temporal Scale: Data records generally span from 1950 to 2022 (with specific station data intervals varying, e.g., 1950-2022 for Siirt, 1959-2022 for Kilis). Analysis was conducted for monthly, seasonal (DJF, MAM, JJA, SON), and annual periods.

Methodology and Data

• Models used:
  • Spatial Interpolation: Inverse Distance Weighting (IDW)
  • Homogeneity Test: Pettitt’s Test (PT)
  • Trend Tests: Mann-Kendall Test (MKT), Spearman’s Rho test (SRT), Wilcoxon test (WT), Sen’s Slope test (SST), Innovative Trend Analysis Significance Test (ITA-ST), Graphical Innovative Trend Analysis (G-ITA).
  • Missing Data Infilling: Arithmetic mean interpolation technique.
• Data sources: Mean monthly temperature (°C) and monthly total precipitation (mm) data obtained from the General Directorate of Meteorology (MGM) of Türkiye.

Main Results

• Spatial Distribution (IDW):
  • Temperature: DJF (winter) was the coldest season (3.26–7.8 °C), while JJA (summer) was the warmest (26.78–32.72 °C). Annual mean temperature ranged from 15.34–19.82 °C. The warmest areas were Cizre, Kilis, Şanlıurfa, Birecik, and Akçakale, with Diyarbakır, Batman, Mardin, Siirt, and Gaziantep being colder.
  • Precipitation: DJF recorded the highest precipitation rates (135.37–375.37 mm), and JJA had the lowest (2.34–11.93 mm). Annual mean total precipitation varied from 285.74–711.47 mm. Highest precipitation was observed in Cizre, Mardin, Adıyaman, and Siirt, while Akçakale, Birecik, and Şanlıurfa had lower values.
• Homogeneity (Pettitt’s Test at α = 0.01): 113 out of 204 temperature series were non-homogeneous (critical years 1978–2008), while only 4 out of 204 precipitation series were non-homogeneous (critical years 1981–1995).
• Trend Analysis (MKT, SRT, WT, SST, ITA-ST, G-ITA at α = 0.01 / 99% confidence):
  • Temperature: A dominance of significant increasing trends was detected across most stations and all monthly, seasonal, and annual scales by MKT, SRT, WT, and ITA-ST. SST indicated almost all positive trend slopes. G-ITA also showed a prevalence of increasing trends. Only Diyarbakır and Akçakale stations showed minor variabilities (few decreasing or no trend cases, mostly non-significant).
  • Precipitation: A prevalence of non-significant decreasing trends was observed across most stations and temporal scales by MKT, SRT, WT. SST frequently noted negative trend slopes. ITA-ST showed a dominance of significantly decreasing trends (95 out of 204 cases). G-ITA also indicated a prevalence of decreasing trends. Precipitation series exhibited more variable behavior compared to temperature.
  • Regional Differences in Precipitation: Eastern stations (Siirt, Mardin, Diyarbakır, Batman, Cizre) generally showed non-significant decreasing trends in January, February, MAM, and annual precipitation, but non-significant increasing trends in most of JJA. Western stations (Gaziantep, Kilis, Adıyaman, Şanlıurfa, Siverek, Birecik, Akçakale) commonly showed non-significant decreasing trends only in March and non-significant increasing trends in August.

Contributions

• This study provides a comprehensive spatio-temporal variability analysis of temperature and precipitation in Southeastern Anatolia, Türkiye, a climatically sensitive transition zone.
• It integrates a wide array of classical non-parametric tests (MKT, SRT, WT, SST) with innovative trend approaches (ITA-ST and graphical ITA), offering a more robust and detailed understanding of regional climate behavior compared to previous studies that often focused on single temporal scales or limited trend detection tests.
• The multi-temporal assessment (monthly, seasonal, annual) allows for evaluation of both short and long-term climate variabilities.
• The findings offer valuable guidance for local authorities in developing effective water resources management plans and climate action plans for risk management and sustainability.

Funding

• Scientific and Technological Research Council of Türkiye (TÜBİTAK)

Citation

@article{Deger2026Exploring,
  author = {Deger, Ibrahim Halil},
  title = {Exploring Monthly, Seasonal and Annual Spatio-Temporal Variability of Temperature and Precipitation Series by Classical and Innovative Techniques},
  journal = {Water Resources Management},
  year = {2026},
  doi = {10.1007/s11269-026-04498-2},
  url = {https://doi.org/10.1007/s11269-026-04498-2}
}