Hydrophobicity Inducement on Laboratory Soil Specimens to Study Wildfire Impacts on Infiltration, Revegetation, and Erosion

Due to longer warm seasons and drought, more fuel is available resulting in wildfires becoming increasingly prevalent in today’s world. Thus, the need for environmental restoration and remediation efforts post-fire has grown, respectively. A fire event can cause hydrophobicity within the top few inches of the soil’s surface, and the presence of this hydrophobic layer when combined with the removal of exterior stabilizers, such as root systems, has the potential to increase runoff by more than ten times the average rate. To rapidly repair these burned environments and preserve any surrounding systems, restoration may be needed. Remedial studies of hydrophobic soils occur in the field or the laboratory on soil samples taken from the field after real fire events. This can make the research site-specific (i.e., unique for a combination of soil and fire characteristics) until the overall quantities of research and analyzed data to reach a broad enough range to develop empirical correlations. This research outlines the development of a standardized procedure for inducing hydrophobic properties onto soils. By standardizing the process to produce hydrophobic specimens, the collection of nonuniform samples from the field can be avoided for fundamental research—before applied field research is pursued—and the degree of soil hydrophobicity can be adjusted to evaluate a range of potential field conditions. The procedure is critical for the development of a range of consistent degrees of hydrophobicity in soil that makes laboratory testing possible. Once the procedure for the inducement of hydrophobicity is standardized and its repeatability is established, further research can be conducted in a more controlled, repeatable, and methodical manner. To standardize and develop hydrophobic properties that most closely resemble field conditions, after generating and analyzing properties of wood-smoke condensates, specimens of Ottawa sand with varying hydrophobic strengths are prepared by applying the condensates. Then, infiltration tests can be performed on these specimens to correlate the impact of hydrophobicity on infiltration through various altered Ottawa sand specimens.