Location: Agroecosystems Management ResearchTitle: Soil water flow due to surface topography in research drainage plots
|CAMBARDELLA, CINDY - Retired ARS Employee|
Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2020
Publication Date: 2/5/2021
Publication URL: https://handle.nal.usda.gov/10113/7709419
Citation: Logsdon, S.D., Cambardella, C. 2021. Soil water flow due to surface topography in research drainage plots. Agrosystems, Geosciences & Environment. 3(1). Article e20128. https://doi.org/10.1002/agg2.20128.
Interpretive Summary: Upslope and downslope positions on the landscape affect how the water moves below the soil surface. The study showed that soil water flowed slowly below the surface. The subsurface redistribution of water kept the water table depth more shallow at the downslope positions on the landscape and deeper for the upper positions on the landscape. The shallow water table depth allowed prolonged tile outflow at the lower positions as water moved from upslope to downslope. Barriers (6' deep) between tiles (4' deep) did not completely prevent the subsurface lateral water flow, but the barriers certainly slowed the lateral water flow. Upslope positions often had water table depths below the barriers even when the water table at some downslope positions was still more shallow than the tile. This information is important for scientists who study tile outflow in field plots.
Technical Abstract: Soils vary spatially even over short distances. The purpose of this study is to determine if surface topography influenced water table depths and water flow patterns in experimental plots. Tiles (1.22 m deep) were installed at the center of each plot, and plastic barriers (1.83 m deep) were installed between plots. Monitoring wells were installed and were read monthly during the growing season. During dry periods the well-drained block had the deepest water table depths (maximum of 4.75 m), and the wettest block had the shallowest water table depths (maximum of 2.15 m). During wet periods, water table depths were similar for all blocks; however, water table gradients were larger during wet periods (for example 3 m) than during dry periods (for example 0.5 m). Mean water table depths for the well-drained block were below the plastic barrier 47% of the time, and below the tile depth 72% of the time. Conversely mean water table depths for the wettest block were deeper than the plastic barrier only 18% of the time, and below the tile 54% of the time. There was slow lateral flow below the barriers from the upslope block to downslope plots; some downslope plots still had tile flow when there was lateral flow from upslope.