A Dual-Method Evaluation of Long-Term Precipitation Changes in Türkiye’s Eastern Black Sea Basin
Abstract
In this study, the long-term and seasonal precipitation dynamics of the Eastern Black Sea Basin were investigated using monthly total precipitation data from six meteorological stations for the period 1994–2024. Two contemporary trend analysis techniques—the Multi-Risk Level Identification (MRLI) method and the Trend Polygon Star Concept Method (TPSCM)—were applied to provide a comprehensive evaluation of precipitation behavior. The MRLI approach identified increasing, decreasing, or stable trends across a range of risk percentiles by determining critical precipitation thresholds from best-fitting theoretical distributions validated through the Kolmogorov–Smirnov (K-S) test. The results revealed substantial spatial variability: while Giresun exhibited consistently increasing trends at all risk levels, Artvin and Trabzon showed mixed behavior with both upward and downward tendencies depending on the percentile. In addition, a basin-wide evaluation indicated that approximately 65% of the overall trends were increasing, whereas 35% displayed decreasing tendencies, highlighting a general intensification of precipitation conditions in the region. The remaining stations showed diverse responses across low-, medium-, and high-risk classes. The TPSCM method offered further insights into intra-annual variability by categorizing month-to-month precipitation transitions into four directional regions representing shifts between early and late sub-periods. The spatial distribution of these regions varied considerably among provinces, indicating notable temporal changes in seasonal rainfall structures. Overall, the combined application of MRLI and TPSCM enabled a detailed assessment of both long-term and seasonal precipitation characteristics, providing a robust basis for advanced hydrological planning and climate adaptation strategies in the Eastern Black Sea Basin.
Keywords
MRLI, TPSCM, Eastern black sea basin, Trend analysis, Precipitation
Supporting Institution
This research received no external funding.
Ethical Statement
This study does not involve human or animal participants. All procedures followed scientific and ethical principles, and all referenced studies are appropriately cited.
Thanks
The author do not wish to acknowledge any individual or institution.
References
- Acar, E., Kankal, M., Akçay, F., & Şan, M. (2022). Innovative polygon trend analyses with star graph for rainfall and temperature data in agricultural regions of Turkey. Environmental Earth Sciences, 81, Article 530. https://doi.org/10.1007/s12665-022-10646-9
- Achite, M., Ceribasi, G., Ceyhunlu, A. I., Wałęga, A., & Caloiero, T. (2021). The innovative polygon trend analysis (IPTA) as a simple qualitative method to detect changes in environment—example detecting trends of the total monthly precipitation in semiarid area. Sustainability, 13(22), Article 12674. https://doi.org/10.3390/su132212674
- Ahmed, N., Wang, G., Booij, M. J., Ceribasi, G., Bhat, M. S., Ceyhunlu, A. I., & Ahmed, A. (2022). Changes in monthly streamflow in the Hindukush–Karakoram–Himalaya Region of Pakistan using innovative polygon trend analysis. Stochastic Environmental Research and Risk Assessment, 36(3), 811-830. https://doi.org/10.1007/s00477-021-02067-0
- Akçay, F., Kankal, M., & Şan, M. (2022). Innovative approaches to the trend assessment of streamflows in the Eastern Black Sea basin, Turkey. Hydrological Sciences Journal, 67(2), 222-247. https://doi.org/10.1080/02626667.2021.1998509
- Ceribasi, G. (2019). Analyzing rainfall datas’ of eastern black sea basin by using sen method and trend methods. Journal of the Institute of Science and Technology, 9(1), 254-264. https://doi.org/10.21597/jist.439569
- Ceribasi, G., Ceyhunlu, A. I., & Ahmed, N. (2021a). Analysis of temperature data by using innovative polygon trend analysis and trend polygon star concept methods: a case study for Susurluk Basin, Turkey. Acta Geophysica, 69(5), 1949-1961. https://doi.org/10.1007/s11600-021-00632-3
- Ceribasi, G., Ceyhunlu, A. I., & Ahmed, N. (2021b). Innovative trend pivot analysis method (ITPAM): a case study for precipitation data of Susurluk Basin in Turkey. Acta Geophysica, 69(4), 1465-1480. https://doi.org/10.1007/s11600-021-00605-6
- Ceribasi, G., Ceyhunlu, A. I., & Celebi, A. (2026). The role of climate change on hydroelectric energy from renewable energy sources: A case study of Sakarya Basin, Türkiye. Ain Shams Engineering Journal, 17(1), Article 103823. https://doi.org/10.1016/j.asej.2025.103823
- Ceyhunlu, A. I., & Cuma, M. (2025). Assessing the impact of climate change on meteorological parameters in the Sakarya River Basin using advanced trend analysis methods. Physics and Chemistry of the Earth, Parts A/B/C, 140, Arrticle 104061. https://doi.org/10.1016/j.pce.2025.104061
- Güçlü, Y. S. (2018). Multiple Şen-innovative trend analyses and partial Mann-Kendall test. Journal of Hydrology, 566, 685-704. https://doi.org/10.1016/j.jhydrol.2018.09.034