Spatio-Temporal Drought Assessment by Using the Innovative Probability of Drought Severity (PDS) Method

Abstract This study examines drought variability across Türkiye from 1960 to 2020, utilizing data from 224 precipitation stations and the Standardized Precipitation Index (SPI) at three temporal scales, SPI-3, SPI-6, and SPI-12, to assess meteorological, agricultural, and hydrological droughts. Temporal analysis reveals two distinct periods, 1960–1990 and 1990–2020, both characterized by increasing drought frequency, particularly in the severe and extreme categories. While drought indices such as SPI, provides time series results, the technical limitations of simultaneously illustrating these time series on a map required the development of an innovative method. To address this challenge, the Probability of Drought Severity (PDS) method was introduced, enabling the spatial representation of derived outputs from the obtained time series. Spatial analysis highlights considerable variability in drought distribution, with shifting drought-prone areas complicating the definition of consistent regional boundaries. The results show higher drought probabilities in Southeastern Anatolia and the Mediterranean regions. Additionally, the study observes increased spatial heterogeneity under normal conditions over the last decade, with greater diversity in map values. Temporal evaluation of the data reveals that the probability of extreme droughts has risen significantly in 2010–2020 phase, reaching unprecedented levels (3,91%, 4,11%, and 4,43%) for SPI-3, SPI-6, and SPI-12, respectively.