A laboratory approach to understand post-wildfire hydrophobicity

Wildfires induced thermal, hydrological, mechanical and chemical changes may lead to the formation of the hydrophobic layer which significantly contributes to slope failure but remains poorly understood. This study aims to develop a standardized laboratory test procedure to repeatedly create hydrophobic layer and measure its persistence and intensity, using furnace to evaluate the effects of heating durations, temperature, and moisture content. Findings suggest that prolonged and more intense wildfire events cause deeper displacement of the hydrophobic layer which may increase the susceptibility of upper soil to mass movement and enhancing slope instability.