Drought regime shifts and changing drought characteristics in Jharkhand, India: A SPEI based analysis from 1951 to 2025

Drought is a recurring hydro-climatic hazard that heavily alters agricultural productivity and depletes water resources. This research investigates the spatiotemporal characteristics of drought in Jharkhand, India, using the Standardized Precipitation Evapotranspiration Index (SPEI) derived from long-term climatic records (1951–2025) acquired from the India Meteorological Department. This research evaluated key drought characteristics: frequency, duration, magnitude, intensity, return period and trend. Trend-Free Pre-Whitening was applied prior to Mann–Kendall and Sen’s slope analyses to ensure robust trend detection, and the Pettitt test was used to identify significant change points in regional drought dynamics. The results identified a significant hydro-climatic transition during 2008–2010, followed by intensified and more persistent drought conditions across Jharkhand. Post-change-point analysis revealed a positive upward trend in drought intensity, ranging from 121.4% to 275.9% in the northeastern part of the region, and an increase in average drought duration ranging from 91.2% to 237.5% in the eastern pockets with droughts of around 4.5 months in the northeast. The changes in drought magnitude were spatially variable, ranging from −72.2% to +150.6% with the greatest positive changes in the northeastern region. The drought frequency increased significantly in the central districts and the drought return period fluctuates overall by around −80.46% to 17% in the Jharkhand state, that is more frequent drought recurrence. Overall, the trend results showed an increasing drought trends especially apparent in the northeastern and northwestern portions, and decreasing drought tendencies in parts of the central region. The Sen’s slope analysis also revealed spatial differences in drought evolution with slopes from around −0.0134 to +0.058. Homogeneity tests (Student’s t-test, Wilcoxon rank-sum test, and F-test) revealed significant changes in mean and distribution at several stations after the identified change point, while variance remained statistically homogeneous across all stations. These findings provide valuable insights for drought monitoring.