Spatiotemporal analysis and mechanisms of drought flood abrupt alternation events in India

India The increasing occurrence of abrupt hydroclimatic shifts, particularly Drought-Flood Abrupt Alternation (DFAA) events, poses significant challenges for water resource management, agriculture, and disaster mitigation. DFAA is classified into drought-to-flood (DTF) and flood-to-drought (FTD) based on the sequences of extremes. Using Standardised Weighted Average Precipitation (SWAP) and daily precipitation data, the study identifies each event and measures its duration, frequency, and intensity. To understand the timing, drivers, and repeating patterns behind these shifts, the analysis uses Continuous Wavelet Transform (CWT), Cross Wavelet Transform (XWT), and Improved Partial Wavelet Coherence (IPWC). The analysis identifies clear hotspots in Gujarat and the northeastern states, where more than one abrupt shift occurs each year. Monthly patterns show that DTF transitions peak at the start of the monsoon in May and June, while FTD transitions are most common during the monsoon retreat in October and November. ENSO shows a strong 3–5-year anti-phase link with event occurrence across most climate zones. NAO and IOD exert growing decadal influence in selected regions. The findings indicate an increasing trend in rapid DTF transition events across all climatic zones, highlighting the need for enhanced forecasting and climate-resilient water management strategies. The study also explains the underlying physical mechanism of DFAA formation and identifies key climatic drivers responsible for its increasing occurrence across India’s climatic zones. • DFAA events are increasing in frequency, duration, and intensity, except in Dry, Arid Desert hot (BWh) climatic zones. • DTF peaks in May–June, FTD in October–November, except in the Upper Himalayas, where DTF occurs in December–January. • ENSO (3–5 years) is the key driver, with NAO and IOD influencing specific regions.