3. Site Description
• Location: Cook Agronomy Farm (CAF) is
approximately 8 km NE of Pullman, WA
• Extent: Tile-drained part of the CAF is
approximately 12 hectares (ha)
• Samples were collected at 12 piezometers and
11 lysimeters throughout the site.
• Discharge samples were collected at a tile
drain on site.
6. Study Goals
• Evaluate how groundwater composition
evolves as the water year progresses and soil
saturation levels fluctuate,
• Determine the contributions of seasonal
precipitation and snow-melt, shallow soil
water, and deep soil water to tile drainage
• Understand vertical mixing processes of
shallow groundwater over the course of a
water year.
7. Hypotheses
• At the beginning of the water year the deep
and shallow groundwater system should be
isolated from one another
• This isolation is due to the loss of
interconnection of flow paths while wetting
up of the soil profile is taking place.
8. Hypotheses
• The values of δ18O in the shallow groundwater
early in the season should be reflective of
“new water” from depleted events early in the
winter season.
• The values for δ18O in the deeper system are
more reflective an averaging effect of winter
precipitation and snow, as it is being
recharged by these waters once the soil
profile is wetted up.
17. Findings
• Primary source of water at tile drain discharge
appears to be from the deep water system.
• Water hydrogeochemistry values converge in
the deep, shallow and TD-12 outlet as the
high-flow season progresses.
• Tile drain δ18O, EC, and Temperature all
appear to react rapidly to large melt-water
and precipitation events. Macro-pore flow?
19. Special Thanks
Thanks to the field crew that
Helped make this happen including
Christopher Kelley, Erin Brooks,
Todd Anderson, William Payne,
Ryan Boylan, and Rebecca Martin