Assessment of Physical Properties of Water-Repellent Soils

This note reports the physical and mechanical properties of two postwildfire sands collected in Southern California chemically induced hydrophobic sand. Hydrophobicity decreases attraction between water molecules solid surfaces manifests a modification hydraulic soil that lead to rain erosion mudflows. Wildfires induce different hydrophobicity levels shallow layers based on fire severity, vegetation, chemistry. assesses applicability laboratory-made soils for studying mudflows by comparing them natural from burned sites will help understand predict mudflow mechanisms. Results show retention curve (SWRC) can be unreliable assessing slopes impacted because suction develops with significant time delay or is absent. Flash floods inclined occur rapidly during rainfall, overflow does not pond slopes. The entry value linearly related drop contact angle characterizes immediate response, which relevant onset.