Hydroclimatic drought trends and change point detection in the Yeşilirmak basin: a comprehensive evaluation using SPI, SPEI, DMI indices and ITA, SQMK, IPTA approaches

Drought was defined as water scarcity resulting from below-normal precipitation in a specific region over an extended period. Analysis of droughts was of vital importance in terms of water resources planning and management, hydropower generation, irrigation planning, agricultural productivity, and reservoir planning. In this study, drought status was evaluated according to the Standard Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), and De Martonne Index (DMI) values calculated between 1979 and 2022 for seasonal and annual periods for Amasya, Çorum, Samsun, and Tokat meteorological stations located in the Yeşilırmak Basin, and station-based drought percentages were expressed. In addition, trend and change point analyses were conducted for each drought index according to Şen’s Innovative Trend Analysis (ITA), Sequential Mann-Kendall (SQMK), and Innovative Polygon Trend Analysis (IPTA) methods. The analysis identified the trends and onset years of droughts in the region, revealing that severe droughts were dominant at a 15% level. ITA results indicated a significant decreasing trend of 5–10% in spring, summer, autumn, and annual periods, alongside an increasing drought trend. SQMK analyses confirmed a general decreasing trend at the stations, while IPTA highlighted the dominance of increasing drought intensities in SPI, SPEI, and DMI trends. These findings underscored the need for policymakers to take proactive measures to mitigate drought risks in the Yeşilırmak Basin. © The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature 2025.