[A-HW37] Global Drought Stress from Headwaters to Lowlands

Wed. May 27, 2026 10:45 AM - 12:15 PM 101 (International Conference Hall, Makuhari Messe)

Chairperson:Livneh Ben(University of Colorado Boulder), Schilling S. Oliver(Hydrogeology, Department of Environmental Sciences, University of Basel, Switzerland), Mankin S Justin(Dartmouth College), Yulizar Yulizar(National Taiwan University), Cook Benjamin(NASA Goddard Institute for Space Studies)

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.

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10:45 AM - 11:00 AM

[AHW37-01] How long do trees take to respond to drought? Insights from semiarid regions

*Sabir oussaoui^1,2,3, Abdessamad Hadri¹, Abdelghani Boudhar^1,4, Ismaguil Hanadé Houmma^1,2,3, Jamal-eddine Ouzemou⁵, El Mahdi El Khalki¹, Ismail Karaoui⁶, Kaoutar Ebbakhali⁴, Mostafa Bousbaa⁵, Christophe Kinnard^2,3 (1. International Water Research Institute (IWRI), Mohammed VI Polytechnic University, Benguerir 43150, Morocco , 2. Department of Environmental Sciences, University of Québec at Trois Rivières, Trois-Rivières, QC G8Z 4M3, Canada , 3. Research Centre for Watershed Aquatic Ecosystem Interactions (RIVE), University of Québec at Trois-Rivières, Trois Rivi-ères, QC G8Z 4M3, Canada, 4. L3G Laboratory, Faculty of Sciences and Techniques, Cadi Ayyad University, Marrakech 40000, Morocco , 5. Center for Remote Sensing Applications (CRSA), Mohammed VI Polytechnic University (UM6P), Benguerir 43150, Morocco, 6. Data4Earth Laboratory, Sultan Moulay Slimane University, Beni Mellal 23000, Morocco )

11:00 AM - 11:15 AM

[AHW37-02] Emerging flash drought dynamics and soil moisture controls in irrigated and non-irrigated landscapes of southern Uzbekistan

*Temur Khujanazarov¹, Valeriya Rakhmatova², Yoshiya Touge³, Bakhriddin Nishonov², Kenji Tanaka¹ (1. Disaster Prevention Research Institute, Kyoto University, 2. Hydrometeorological Research Institute, Uzbekistan, 3. Institute for Advanced Academic Research, Chiba University)

11:15 AM - 11:30 AM

[AHW37-03] Assessing Snow Drought Impacts on Water Supply Through Remote Sensing and Hydrologic Modeling

*Noah P Molotch¹, Emma Tyrrell¹, Leanne Lestak¹ (1. University of Colorado Boulder)

11:30 AM - 11:45 AM

[AHW37-04] Changes in seasonal snow and downstream drought predictability: an examination of projected western U.S. water resources

*Kaitlyn Mariye Bishay¹, Ben Livneh^1,2,3, Zhi Li^1,4 (1. Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado, 2. Cooperative Institute for Research In Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, 3. Western Water Assessment, University of Colorado Boulder, Boulder, Colorado, 4. Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, Colorado)

11:45 AM - 12:00 PM

[AHW37-05] From peaks to people: Bridging the gap between headwater snow droughts and downstream water security

*Ben Livneh^1,2,3, Benet Duncan^1,2,3 (1. University of Colorado Boulder, 2. Cooperative Institute for Research in Environmental Sciences, 3. Western Water Assessment)

12:00 PM - 12:15 PM

[AHW37-06] Improving AMSR2 snow depth retrieval through interpretable machine learning for enhanced snow drought assessment

*Kehan Yang^1,2, Sujay V. Kumar², Goutam Konapala³, Justin M. Pflug^4,2, Carrie M. Vuyovich², Ehsan Jalilvand^5,2, Yeosang Yoon^5,2, Wegiel W. Jerry^5,2 (1. Science Systems and Applications, Inc., Lanham, MD, USA., 2. Hydrological Sciences Lab, NASA Goddard Flight Center, Greenbelt, MD, USA, 3. Pacific Northwest National Laboratory, Ames, Iowa, USA., 4. Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA, 5. Science Applications International Corporation, McLean, VA, USA.)

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