EFFECTS OF A SUBSURFACE INTERCEPTION DRAINAGE SYSTEM ON SOIL-MOISTURE REGIME IN A SALINE-SEEP AREA

The temporal and spatial relations of soil water with interception drainage of a side-hill saline seep area, cropped partly to alfalfa, in southern Alberta was characterized from 1986 to 1988. The three interceptor drains were at a depth of 1.55, 1.67, and 1.78 m, respectively, approximately midway down the drainfield. Their effect on phreatic level and soil-water content was more pronounced upslope than downslope from the drainlines. Soil-water content in the 0 - 1.50 m depth decreased over time with increase in depth to watertable. Spatially, the soil water indicated a critical depth of capillary rise of water from the watertable of between 1.60 and 2.00 m, with the latter depth substantiated by simulation analysis. These improvements in soil-water regime and phreatic level will aid in assessing the adequacy of interception drainage for salinity control and crop production.