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Water stress is intensifying in many parts of the world due to more severe and less predictable drought events. Improving our understanding of these events requires a holistic view that follows drought signals from their origin, often in high-elevation headwaters to downstream regions where impacts may be even greater. While drought science has historically focused on processes driven by rainfall deficits, there is growing consensus that changes in the world's montane "water towers" can trigger and amplify drought stress across entire basins.  This session seeks to bridge the gap between headwater drought science and the study of droughts in non-headwater systems, addressing the pressing challenges in understanding these key regional differences. 
An increasingly important driver in headwater systems is "snow drought," where declining snowpacks and a shift from snow to rain, lead to reduced summer water availability. This process creates local water stress but also makes water availability less predictable for downstream regions. These snow signals propagate through river networks and groundwater systems, often compounding the effects of local precipitation deficits in lowland agricultural and in urban areas. Key questions include: How do headwater anomalies translate to downstream risks? Where are the global hotspots for this interconnected drought stress? What are examples of more-vs-less resilient water systems?
This session invites contributions that explore different components of the lifecycle of drought. We are inspired by collaborative efforts like the IAHS "Droughts in Mountain Regions" working group, and aim to cultivate a similar dialogue that spans the full headwater-to-lowland continuum. We welcome submissions on changing snow dynamics, groundwater interactions, the modeling of drought propagation, the compound effects of climate anomalies on water stress, as well as assessments of risk and resilience for communities across entire basins.