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The effects of climate change and extreme wildfire events on runoff erosion over a mountain watershed
Gould G.K., Liu M., Barber M.E., Cherkauer K.A., Robichaud P.R., Adam J.C. 2016.
The effects of climate change and extreme wildfire events on runoff erosion over a mountain watershed.
Journal of Hydrology 536:71-91.
http://dx.doi.org/10.1016/j.jhydrol.2016.02.025
Keywords: Wildfire, Erosion, Climate change, WEPP model, Hydrology.
Links:
PDF [3.19 MB]
Abstract:
Increases in wildfire occurrence and severity under an altered climate can substantially impact terrestrial
ecosystems through enhancing runoff erosion. Improved prediction tools that provide high resolution
spatial information are necessary for location-specific soil conservation and watershed management.
However, quantifying the magnitude of soil erosion and its interactions with climate, hydrological processes,
and fire occurrences across a large region (>10,000 km2) is challenging because of the large computational
requirements needed to capture the fine-scale complexities of the land surface that govern
erosion. We apply the physically-based coupled Variable Capacity Infiltration–Water Erosion
Prediction Project (VIC–WEPP) model to study how wildfire occurrences can enhance soil erosion in a
future climate over a representative watershed in the northern Rocky Mountains – the Salmon River
Basin (SRB) in central Idaho. While the VIC model simulates hydrologic processes at larger scales, the
WEPP model simulates erosion at the hillslope scale by sampling representative hillslopes.
VIC–WEPP model results indicate that SRB streamflow will have an earlier shift in peak flow by one to
two months under future climate scenarios in response to a declining snowpack under warming temperatures.
The magnitude of peak flow increases with each higher severity fire scenario; and under the highest
fire severity, the peak flow is shifted even earlier, exacerbating the effects of climate change. Similarly,
sediment yield also increases with higher fire severities for both historical and future climates. Sediment
yield is more sensitive to fire occurrence than to climate change by one to two orders of magnitude,
which is not unexpected given that our fire scenarios were applied basin wide as worst case scenarios.
In reality, fires only occur over portions of the basin in any given year and subsequent years’ vegetation
regrowth reduces erosion. However, the effects of climate change on sediment yield result in greater spatial
heterogeneities, primarily because of the spatial differences in precipitation projections, while fire
conditions were uniformly applied. The combined effects of climate change and a possible continuation
of increasing fire frequency and severity will compound excess sediment issues that already exist in this
region of the intermountain West.
Moscow FSL publication no. 2016b
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