Determination of Hydraulic Properties in Water Repellent Soils.

Water repellency is a widespread phenomenon in soils and examining the effect of soil water repellency (SWR) on soil water flow is crucially important.  Water flow in soils is controlled by many different factors such as soil texture and the soil hydraulic properties.   Measurements of hydraulic properties in water repellent soils are usually inaccurate because different water contents are present at equal capillary pressures in water repellent soils compared with completely wettable soils.  The objective of this study was to determine the hydraulic properties in water repellent soils from North Eastern Alberta.  Water retention curves and saturated hydraulic conductivities were determined using water and equivalent pressures with 95% ethanol on soils with various degrees of repellency.  Ethanol is often used in comparison with water to measure infiltration rates and sorptivities for determination of hydraulic properties as its flow is independent of surface properties.  As such, determination of intrinsic hydraulic properties can be determined.   In soils observed in the field SWR is dynamic in nature, which is reversible in the presence of water.  Therefore it is necessary to test the change in hydraulic properties due to SWR in soils with reversible wettability. Improved determination of hydraulic properties in water repellent soils will improve management and modeling application.