Sponsor
Portland State University. Department of Environmental Science and Management
First Advisor
Kelly Gleason
Term of Graduation
Fall 2024
Date of Publication
1-22-2025
Document Type
Thesis
Degree Name
Master of Science (M.S.) in Environmental Science and Management
Department
Environmental Science and Management
Language
English
Subjects
Forest Fires, Mid-Winter Snowmelt, Rain on Snow, Snow Hydrology
Physical Description
1 online resource (vi, 82 pages)
Abstract
As the spatiotemporal overlap between burned forests, seasonal snow, extreme precipitation, and mid-winter warming continues to increase with climate change, it is critical we quantify the impacts of forest fires and rain-on-snow (ROS) on mid-winter snowmelt and snow-water resources. In the Pacific Northwest, the release of large volumes of meltwater to downstream receiving water from already vulnerable snowpacks can have catastrophic consequences. I show that forest fires doubled mid-winter snowmelt proportions as compared to unburned reference sites, using a novel network of snow monitoring and micrometeorological stations installed across an elevational and forest type gradient in a burned watershed in the western Oregon Cascades. I also observed an increase in snowpack vulnerability during ROS events in the burned forests, particularly at mid elevations, where ROS induced snowmelt accounted for 22.5% more of annual snowmelt. As a result, total springtime snowpack storage was reduced by half compared to the unburned sites, due to more snowpack loss during midwinter rain-on-snow events than at the unburned sites. Higher net snowpack energy, driven primarily by longwave radiation at the lower and middle elevations, indicates minimal buffering capacity of these warm snowpacks in high density burned forest to increasingly common ROS events. Balancing preparations for mid-winter flooding due to increased ROS vulnerability and refining the timing of water storage to offset accelerated snow disappearance represents a pressing challenge for water managers in a changing climate.
Rights
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Persistent Identifier
https://archives.pdx.edu/ds/psu/42994
Recommended Citation
Ebel, Sage, "Forest Fires Increase Mid-Winter Snowmelt in the Western Oregon Cascades" (2025). Dissertations and Theses. Paper 6751.
Comments
Funding support from the United States Army Corps of Engineers, Research and Development Center, contract #W912HZ2220004.