Patterns of water movement on a logged Gray Luvisolic hillslope during the snowmelt period

Hillslope flow processes during the snowmelt period were studied at a logged site in the Boreal Plain Ecozone of western Canada. Fine-textured subsoils of Gray Luvisolic soils and soil frost were hypothesized to reduce infiltration capacity and promote interflow. Liquid soil water content, saturated flow through upper horizons, and soil temperature were monitored by Time Domain Reflectometry probes, zero-tension flow collectors, and thermocouples, respectively, on a 0.5-ha site with a 13% slope. Soil water content increased abruptly during snowmelt while soil temperature in the upper 65 cm was near 0°C, indicating that infiltration capacity was high despite frost. Mineral soil thawed 2 wk after snowmelt. Less than 0.1 mm of the 87 mm snow water equivalent became interflow. Size and timing of interflow events were variable and related to increased soil water content. The largest event occurred during soil thaw, and contributed 84% of total interflow. The lower Ae horizon was the preferred route for this flow, suggesting that the flowpath was not influenced by frost. Low pre-melt soil moisture probably reduced interflow volume. Interflow in Gray Luvisols is likely an infrequent happening due to high profile moisture storage capacity and rare development of the necessary saturated conditions.