Hydroclimatological Controls on Wind Erosion of Soil Following Wildfire

In this study we examine the effects of soil and atmospheric moisture on the wind erodibility of soil following a wildfire at the U.S. Department of Energy, Idaho National Laboratory in southeastern Idaho. We measured threshold wind velocities (as a measure of erodibility), soil volumetric water content, as well as air temperature, relative humidity, and vapor density at burned and unburned sites. This data was measured simultaneously at 5-minute intervals between August 23rd – December 10th, 2008. Passive sediment collectors were also used to determine sediment horizontal mass transport at burned and unburned sites. Results indicate that erodibility decreased with time following the burn. A corresponding decrease in sediment transport at the burned sites was measured over the same time period. Comparatively little sediment transport was detected at the unburned site and erodibility could not be determined due to the lack of erosion. Soil and atmospheric moisture were significantly correlated with erodibility at the burned sites. Multiple regression models with soil water content, air relative humidity, air vapor density and time as predictors explained substantial variability in erodibility (adjusted r2 = 0.83 and 0.64 at heavy and light burn intensity sites, respectively). These results indicate that near surface atmospheric moisture and soil water are important factors controlling the wind erodibility of recently burned surfaces in this environment.