Multi-Index evaluation of meteorological drought across Türkiye: a temporal and seasonal perspective

Abstract Türkiye, situated in the Mediterranean Basin, is highly susceptible to drought due to its predominantly semi-arid climate. This study aims to evaluate the temporal and seasonal dynamics of drought across Türkiye by employing three distinct drought indices: the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), and the Percent of Normal Index (PNI). Long-term spanning the period 1972–2023, monthly areal average precipitation data derived through Kriging interpolation and monthly average temperature data from 255 meteorological stations were used. Drought assessments were conducted on both monthly and seasonal scales, with SPI and SPEI calculated at 3-, 6-, 9-, 12-, and 24-month timescales to capture meteorological, agricultural, and hydrological drought characteristics. The results revealed that the most severe drought occurred during 2007–2009 with nationwide SPI values dropping below − 2.0. Severe droughts (SPI < − 1.5) were observed in approximately 18% of the study period, with summer droughts being 30–35% more frequent than winter droughts. During 2020–2023, more than 70% of stations simultaneously experienced drought conditions, highlighting the increasing influence of temperature-driven evapotranspiration. Notably, SPEI values were consistently lower than SPI during summer and autumn, reflecting the intensifying role of rising temperatures and Potential Evapotranspiration (PET), while PNI corroborated these findings and emphasized Türkiye’s heightened drought sensitivity during the summer season. This study demonstrates the added value of temperature-based indices in drought monitoring and provides essential insights for, drought early warning systems, and water resource management in drought-prone regions. The Mann–Kendall analysis indicates an overall increase in drought severity after 2000, marked by temperature-driven summer drying and a slight winter wetting tendency.