Pre-Season Wet Soil Produces Fire-Prone Conditions – GWC Mag

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Source: Geophysical Research Letters

Identifying precursors to wildfire incidents is essential for forecasting and alleviating the consequences of wildfires. According to a new study by Alizadeh et al. [2024], this can be accomplished based on data from the Soil Moisture Active Passive (SMAP) satellite.

The authors analyzed the temporal dynamics of SMAP soil moisture and vegetation water content preceding and following 5,691 large fires (i.e., burned areas > 1,000 acres each), and compared it with the mean and no-fire conditions. In the western United States regions (including the Northwest, West, Southwest, and Northern Rockies and Plains), soil was found to be wetter than normal approximately five months prior to fire ignition, promoting vegetation growth and buildup of fire fuel. This wet spell was followed by a rapid dehydration of soil and vegetation in the months leading up to the fire, creating favorable ignition conditions.

The antecedent wet conditions regulate wildfire activity by increasing the fuel availability, which is important in fuel-limited systems such as those typically found in the western U.S.; a similar pattern was not found in the eastern U.S. where there is sufficient biomass for fuel, but fire is limited by flammability. This study underscores the importance of considering soil moisture dynamics as a key factor in evaluating wildfire risk.

Citation: Alizadeh, M. R., Adamowski, J., & Entekhabi, D. (2024). Land and atmosphere precursors to fuel loading, wildfire ignition and post-fire recovery. Geophysical Research Letters, 51, e2023GL105324. https://doi.org/10.1029/2023GL105324

— Guiling Wang, Editor, Geophysical Research Letters

Text © 2024. The authors. CC BY-NC-ND 3.0
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