Whiplash and Shifts in Hydrological Regimes: Unfolding Challenges in Water Management Facing Different Futures

Intensifying hydrological extremes and their compound interactions, particularly drought-to-flood transitions, present significant challenges for water resource management. Despite their critical importance, the mechanisms underlying these complex interactions remain poorly understood, needing comprehensive analytical frameworks for effective water resource governance. Here, we investigate flow regime shifts in a tropical basin by integrating hydrological alteration indices and hydroclimate volatility. Changes in observed and projected flow regimes were quantified in terms of their range of variability in key indicators of alteration (flow magnitude, timing, and frequency). Additionally, a hydroclimate whiplash index was implemented to identify rapid wet-to-dry and dry-to-wet transitions. Our analysis reveals substantial alterations in flow magnitude and variability, with the most pronounced changes occurring toward the end of the century. All scenarios demonstrate increased volatility characterized by more frequent and abrupt transitions between hydrological extremes—more frequent wetter dry seasons and drier wet seasons. These more frequent rapid and abrupt regime shifts impose additional pressure on water resources, threatening sustainable planning and management. These findings highlight the inadequacy of traditional stationarity-based infrastructure under projected climate conditions. Our results emphasize the urgent need for adaptive water management strategies that acknowledge climate uncertainty and incorporate flexible responses to hydrological volatility. The integrated application of hydrologic alteration metrics and hydroclimate whiplash indices provides a novel analytical framework for assessing future water-related risks and informing resilient planning strategies in tropical basins facing compound climate stressors.