Many forested watersheds with a substantial fraction of precipitationdelivered as snow have the potential for landscape disturbance by wildfire.Little is known about the immediate effects of wildfire on snowmelt andnear-surface hydrologic responses, including soil-water storage. Montanesystems at the rain-snow transition have soil-water dynamics that arefurther complicated during the snowmelt period by strong aspect controls onsnowmelt and soil thawing. Here we present data from field measurements ofsnow hydrology and subsurface hydrologic and temperature responses duringthe first winter and spring after the September 2010 Fourmile Canyon Fire inColorado, USA. Our observations of soil-water content and soil temperatureshow sharp contrasts in hydrologic and thermal conditions between north- andsouth-facing slopes. South-facing burned soils were ∼1–2 °C warmeron average than north-facing burned soils and ∼1.5 °C warmer thansouth-facing unburned soils, which affected soil thawing during the snowmeltperiod. Soil-water dynamics also differed by aspect: in response to soilthawing, soil-water content increased approximately one month earlier onsouth-facing burned slopes than on north-facing burned slopes. While aspectand wildfire affect soil-water dynamics during snowmelt, soil-water storageat the end of the snowmelt period reached the value at field capacity foreach plot, suggesting that post-snowmelt unsaturated storage was notsubstantially influenced by aspect in wildfire-affected areas. Our data andanalysis indicate that the amount of snowmelt-driven groundwater rechargemay be larger in wildfire-impacted areas, especially on south-facing slopes,because of earlier soil thaw and longer durations of soil-water contentsabove field capacity in those areas.
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