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    Öğe
    An evaluation of spatiotemporal changes of meteorological drought in the Mediterranean sub-basins in Türkiye using discrepancy precipitation and standardized precipitation index
    (Springer, 2024) Degerli Simsek, Serin; Turhan, Evren
    Detecting dry and wet periods is crucial for regions susceptible to drought impacts. The present study analyzed the dry and wet periods using precipitation data obtained from 8 gauging stations along the Central Mediterranean coast of T & uuml;rkiye. A span of 52 years, from 1970 to 2021, was examined utilizing three distinct methods: the Standardized Precipitation Index (SPI-Gamma, SPI-Lognormal), Discrepancy Precipitation Index (DPI), and Reconnaissance Drought Index (RDI). Initially, the study discussed the changes in dry and wet periods observed at the respective stations. Subsequently, it determined the transition probabilities associated with classifications of drought. The results showed that SPI-G values exhibit greater precision in detecting wet periods, while the SPI-L method yields more specific outcomes in identifying dry periods. Notably, the DPI method demonstrates a higher frequency of dry periods than the SPI method. Additionally, findings from the SPI method suggest that reductions in drought indices correspond to an increased occurrence of drought. The DPI method's outputs indicate fewer occurrences of wet periods across all stations in contrast to the results obtained through the SPI method. The study stands out by addressing the assessment of drought development in the Mediterranean coastal regions of T & uuml;rkiye using the DPI method, which has recently garnered attention in the literature, presenting a novel contribution within the scope of this research.
  • [ X ]
    Öğe
    Investigating drought trends with new and traditional drought indices using innovative trend analysis (ITA): A case of Seyhan, Ceyhan, and Asi River Basins, Türkiye
    (Springer, 2026) Degerli Simsek, Serin; Turhan, Evren
    Accurate monitoring of drought conditions requires the use of quantitative indices that capture the variability of precipitation and other climatic parameters. The development and comparison of such indices provide valuable insights for both scientific understanding and practical applications in drought management. This study investigated historical drought trends in T & uuml;rkiye's Seyhan, Ceyhan, and Asi River basins by employing indices such as Standardized Precipitation Index (SPI), Reconnaissance Drought Index (RDI), Discrepancy Precipitation Index (DPI), and New Drought Index (NDI). Given the growing importance of understanding drought dynamics, these indices were selected to ensure a comprehensive evaluation by incorporating distinct climatic parameters such as precipitation, evapotranspiration, and temperature. 13 meteorological stations were examined to ensure data reliability and accuracy for the years 1970 to 2021. The drought indices were calculated, and their temporal trends were analyzed using the Innovative Trend Analysis (ITA) method. The 52-year dataset was divided into three distinct periods for detailed trend evaluation. Partitioning the 52-year record for ITA revealed widespread negative NDI trends in the third period (nearly all stations) with a persistent wetting signal at Karata & scedil;, while RDI declines were pronounced at Karaisal & imath; and Kahramanmara & scedil;. Correlation analyses revealed that SPI and RDI showed strong alignment due to their common reliance on precipitation data. In contrast, NDI, which includes temperature as a parameter, exhibited broader sensitivity, indicating its ability to detect extreme wet and drought periods more effectively. Findings highlighted significant spatial and temporal variability in drought conditions. Across 13 stations (1970-2021), all four indices converged on the same extreme years, six wet (1976, 1981, 1987, 1988, 1997, 2009) and six dry (1989, 1990, 1993, 2013, 2017, 2020), demonstrating cross-index consistency in event detection. Overall, the study underscores the critical need for employing multiple drought indices to capture complex climatic dynamics accurately. It also emphasizes the utility of integrating newly developed indices like DPI and NDI into drought monitoring frameworks. The findings suggest that future drought management strategies should consider index-specific sensitivities and regional climatic characteristics for precise drought assessments.