Bing Cheng Si, Henry Chau and Amanda Hunter.
Department of Soil Science, University of Saskatchewan

Soil water repellency (SWR) has an adverse effect on environmental quality due to reduced infiltration, increased overland flow, increased preferential flow, decreased water storage and increased soil erosion. The presence of SWR is reported in all types of soils at variable degrees as such its role in soil hydrology is extremely important. Water repellency in soils is controlled by the critical soil water content (water content at which soils changes from a repellent to a wettable state). The purpose of this study is to determine the water repellency and the critical soil water contents in natural and reclaimed landscapes. Soil water repellency was measured using tension infiltrometers at field conditions. Soil samples were also collected from natural and reclaimed sites located in the Athabasca Oil Sands region, as well as two soils from Saskatchewan for texturally contrast comparison. The collected soil samples were sieved through 2 mm and initial soil water content was determined.  Additional water was added to obtain a series of uniform water contents (OD, AD, 2.5%, 5%, 7.5%, 8.5%, 10%, 12.5%, 15% and 17.5%).  Using the modified sessile drop method, contact angles were measured on the surface of the soil.  Soil water contents were determined immediately after measurements by drying at 105°C for 24 hours. Almost all field soils exibiht certain degree of water repellency and critical water content (θCR) between the soils ranged from 0 % - >17 %.  A number of these soils had high critical water content (θCR >12%), suggesting a significant concern of SWR in these soils. Due to the presence of SWR in all types of soil, the critical soil water content must be taken into consideration when understanding the hydrology of a water repellent soil.