Conceptual blind spots in dry-season water management research under climate amplification in regulated tropical basins

ABSTRACT Three-stage graphical abstract. Conventional volumetric indicators can mask short critical dry-season windows. The climate-timing lens asks when water is usable, for how long, and with what confidence using timing, persistence and thresholds. Forecasting threshold crossings then supports adaptive operational actions and protects usable water windows. Dry-season water stress in regulated tropical basins is often assessed as a volumetric deficit, although operational failures may occur when seasonal supply appears adequate. This review identifies four structural blind spots: temporal aggregation bias, continuity assumptions under non-stationarity, quantity-quality decoupling, and science-decision mismatch. A critical synthesis of hydrology, water-quality, modelling, forecasting and governance literature supports a climate-timing paradigm that defines availability through usable-water windows. The framework evaluates onset, duration, persistence, recovery and probability of threshold exceedance at decision-relevant spatial and temporal scales. It complements process-based, distributed, machine-learning and ensemble models by translating their outputs into forecast probabilities and action triggers. A six-step operational workflow specifies monitoring inputs, uncertainty sources, forecast horizons, decision rules and adaptive actions. Examples from the Mekong, South Asian and southern African systems illustrate scale-dependent quantity-quality and sectoral trade-offs. The synthesis further shows that thresholds vary with climate scenario, location, purpose and social vulnerability. Focusing on when water is usable, for how long and with what confidence provides a practical bridge between hydrological analysis and equitable dry-season adaptation.