Location: Northwest Watershed Research CenterTitle: Recovery of small-scale infiltration and erosion after wildfires
|LARSON-NASH, SIERRA - Us Forest Service (FS)|
|ROBICHAUD, PETER - Us Forest Service (FS)|
|Williams, Christopher - Jason|
|SPAETH, KENNETH - Natural Resources Conservation Service (NRCS, USDA)|
|BROWN, ROBERT - Us Forest Service (FS)|
|LEWIS, SARAH - Us Forest Service (FS)|
Submitted to: Journal of Hydrology and Hydromechanics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2017
Publication Date: 8/14/2018
Citation: Larson-Nash, S.S., Robichaud, P.R., Pierson, F.B., Moffet, C.A., Williams, C.J., Spaeth, K.E., Brown, R.E., Lewis, S.A. 2018. Recovery of small-scale infiltration and erosion after wildfires. Journal of Hydrology and Hydromechanics. 66(3):261-270. https://doi.org/10.1515/johh-2017-0056.
Interpretive Summary: Mitigation of elevated runoff and erosion from burned areas remains a primary concern in reducing risks to natural resources, property, infrastructure, and human life. This study conducted rainfall simulation and mini-disk infiltrometer experiments to investigate impacts of high severity wildfire on infiltration, runoff generation, and soil erosion immediately after and 1, 2, and 5 yr following a wildfire across rangeland and dry forest vegetation. Vegetation recovery was slow across the high severity burn area over the 5 yr study. The prolonged vegetation recovery facilitated high levels of runoff and sediment in each study year and infiltration remained lower and erosion remained higher in the burned area than in unburned areas after 5 yr. Mini-disk infiltrometer measurements accurately depicted fire effects on infiltration and runoff as measured with the more rigorous rainfall simulation experiments. Collectively, the results contribute to improved scientific understanding of post-fire hydrologic and erosion responses and demonstrate the mini-disk infiltrometer utility for rapid assessment of fire impacts on infiltration and runoff generation.
Technical Abstract: Rainfall simulation plots were established after the 2003 Hot Creek Fire in Idaho, USA to evaluate the impacts of high severity wildfire on infiltration and interrill erosion responses. Measurements were initiated after the wildfire and repeated in 2004, 2005, and 2008 on burned and unburned plots. Relative infiltration from mini-disk tension infiltrometer (MDI) measurements was estimated at the soil surface, 1- and 3-cm soil depths. Vegetation recovery was slow with median cover of 6–8% on burned sites after 5 years. Consequently, sediment yields were still significantly higher on the burned sites (329–1200 g m-2) compared to the unburned sites (3–35 g m-2) in year 5. Total infiltration on the burned plots increased during the study period, yet remained lower than on the unburned control plots. Relative infiltration measurements were significantly correlated to non-steady state total infiltration values taken at the 3-, 5-, and 10-min marks within the hour-long rainfall simulations. Correlations were strongest at the 1-cm depth, '=0.4–0.6 and at the 3-cm depth, '=0.3–0.5. These results suggest that sub-surface relative infiltration measurements may be useful to estimate potential infiltration during a short-duration high-intensity storm and could be used as an input for post-fire erosion models.