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Watershed memory amplified the Oroville rain-on-snow flood of February 2017

Mountain snowpacks are transitioning to experience less snowfall and more rainfall as the climate warms, creating more persistent low- to no-snow conditions. This precipitation shift also invites more high-impact rain-on-snow (ROS) events, which have historically yielded many of the largest and most...

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Autores principales: Haleakala, Kayden, Brandt, W Tyler, Hatchett, Benjamin J, Li, Dongyue, Lettenmaier, Dennis P, Gebremichael, Mekonnen
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9832955/
https://www.ncbi.nlm.nih.gov/pubmed/36712942
http://dx.doi.org/10.1093/pnasnexus/pgac295
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author Haleakala, Kayden
Brandt, W Tyler
Hatchett, Benjamin J
Li, Dongyue
Lettenmaier, Dennis P
Gebremichael, Mekonnen
author_facet Haleakala, Kayden
Brandt, W Tyler
Hatchett, Benjamin J
Li, Dongyue
Lettenmaier, Dennis P
Gebremichael, Mekonnen
author_sort Haleakala, Kayden
collection PubMed
description Mountain snowpacks are transitioning to experience less snowfall and more rainfall as the climate warms, creating more persistent low- to no-snow conditions. This precipitation shift also invites more high-impact rain-on-snow (ROS) events, which have historically yielded many of the largest and most damaging floods in the western United States. One such sequence of events preceded the evacuation of 188,000 residents below the already-damaged Oroville Dam spillway in February 2017 in California’s Sierra Nevada. Prior studies have suggested that snowmelt during ROS dramatically amplified reservoir inflows. However, we present evidence that snowmelt may have played a smaller role than previously documented (augmenting terrestrial water inputs by 21%). A series of hydrologic model experiments and subdaily snow, soil, streamflow, and hydrometeorological measurements demonstrate that direct, “passive” routing of rainfall through snow, and increasingly efficient runoff driven by gradually wetter soils can alternatively explain the extreme runoff totals. Our analysis reveals a crucial link between frequent winter storms and a basin’s hydrologic response—emphasizing the role of soil moisture “memory” of within-season storms in priming impactful flood responses. Given the breadth in plausible ROS flood mechanisms, this case study underscores a need for more detailed measurements of soil moisture along with in-storm changes to snowpack structure, extent, energy balance, and precipitation phase to address ROS knowledge gaps associated with current observational limits. Sharpening our conceptual understanding of basin-scale ROS better equips water managers moving forward to appropriately classify threat levels, which are projected to increase throughout the mid-21st century.
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spelling pubmed-98329552023-01-26 Watershed memory amplified the Oroville rain-on-snow flood of February 2017 Haleakala, Kayden Brandt, W Tyler Hatchett, Benjamin J Li, Dongyue Lettenmaier, Dennis P Gebremichael, Mekonnen PNAS Nexus Research Report Mountain snowpacks are transitioning to experience less snowfall and more rainfall as the climate warms, creating more persistent low- to no-snow conditions. This precipitation shift also invites more high-impact rain-on-snow (ROS) events, which have historically yielded many of the largest and most damaging floods in the western United States. One such sequence of events preceded the evacuation of 188,000 residents below the already-damaged Oroville Dam spillway in February 2017 in California’s Sierra Nevada. Prior studies have suggested that snowmelt during ROS dramatically amplified reservoir inflows. However, we present evidence that snowmelt may have played a smaller role than previously documented (augmenting terrestrial water inputs by 21%). A series of hydrologic model experiments and subdaily snow, soil, streamflow, and hydrometeorological measurements demonstrate that direct, “passive” routing of rainfall through snow, and increasingly efficient runoff driven by gradually wetter soils can alternatively explain the extreme runoff totals. Our analysis reveals a crucial link between frequent winter storms and a basin’s hydrologic response—emphasizing the role of soil moisture “memory” of within-season storms in priming impactful flood responses. Given the breadth in plausible ROS flood mechanisms, this case study underscores a need for more detailed measurements of soil moisture along with in-storm changes to snowpack structure, extent, energy balance, and precipitation phase to address ROS knowledge gaps associated with current observational limits. Sharpening our conceptual understanding of basin-scale ROS better equips water managers moving forward to appropriately classify threat levels, which are projected to increase throughout the mid-21st century. Oxford University Press 2022-12-16 /pmc/articles/PMC9832955/ /pubmed/36712942 http://dx.doi.org/10.1093/pnasnexus/pgac295 Text en © The Author(s) 2022. Published by Oxford University Press on behalf of the National Academy of Sciences. https://creativecommons.org/licenses/by/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Report
Haleakala, Kayden
Brandt, W Tyler
Hatchett, Benjamin J
Li, Dongyue
Lettenmaier, Dennis P
Gebremichael, Mekonnen
Watershed memory amplified the Oroville rain-on-snow flood of February 2017
title Watershed memory amplified the Oroville rain-on-snow flood of February 2017
title_full Watershed memory amplified the Oroville rain-on-snow flood of February 2017
title_fullStr Watershed memory amplified the Oroville rain-on-snow flood of February 2017
title_full_unstemmed Watershed memory amplified the Oroville rain-on-snow flood of February 2017
title_short Watershed memory amplified the Oroville rain-on-snow flood of February 2017
title_sort watershed memory amplified the oroville rain-on-snow flood of february 2017
topic Research Report
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9832955/
https://www.ncbi.nlm.nih.gov/pubmed/36712942
http://dx.doi.org/10.1093/pnasnexus/pgac295
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