Quantifying Aspect-Dependent Snowpack Response to High-Elevation
Wildfire in the Southern Rocky Mountains
Abstract
Increasing wildfire frequency and severity in high-elevation seasonal
snow zones presents a considerable water resource management challenge
across the western U.S. Wildfires can affect snowpack accumulation and
melt patterns, altering the quantity and timing of runoff. While prior
research has shown that wildfire generally increases snow melt rates and
advances snow disappearance dates, uncertainties remain regarding
variations across complex terrain and the energy balance between burned
and unburned areas. Utilizing multiple paired in-situ data sources
within the 2020 Cameron Peak burn area during the 2021–2022 winter, we
found no significant difference in peak snow water equivalent (SWE)
magnitude between burned and unburned areas. However, the burned south
aspect reached peak SWE 22 days earlier than burned north. During the
ablation period, burned south melt rates were 71% greater than unburned
south melt rates, whereas burned north melt rates were 94% greater than
unburned north aspects. Snow disappeared 7 to 11 days earlier in burned
areas than unburned areas. Net energy differences at the burned and
unburned AWS sites were seasonally variable, with the burned area losing
more energy during the winter but gaining significantly more energy
during the spring. Net shortwave radiation was 56% greater at the
burned area during the winter and 137% greater during the spring
driving a ~60% greater cumulative net energy at the
burned site during May. These findings emphasize the need for
post-wildfire water resource planning that accounts for aspect-dependent
differences in energy and mass balance to accurately predict snowpack
storage and runoff timing.