Title: Interflow of water and tracer chemical on sloping field plots with exposed seepage faces
Abstract: Four experimental field plots, each 1.8 m wide and 8.0 m long on 6–8% slope, were isolated from each other and the surrounding area by sheet metal plates extending from 0.15 m above to 0.9 m below the surface of a Typic Paleudults soil. An open soil face ∼ 0.7 m deep, divided into three natural horizons, formed the lower end of each plot in a runoff monitoring pit. The plots were used to measure water and tracer chemical flows when simulated rainfall was applied at rates of 1.5–2.5 cm hr.−1 to soil that was initially either nearly saturated, or initially near the wilting point for the grass cover. Potassium bromide solution was used to trace the fate of a surface-applied mobile chemical. Rainfall partitioning among flows did not vary appreciably among three of the four plots, but one plot had a matrix of relatively abundant soil macropores that enhanced interflow. Excluding that plot, average partitioning of the rainfall among plots for three separate experiments was: 66% to runoff, 11.2% to interflow, and 22.8% to seepage below the 0.7-m depth of interflow measurement. Saturated initial soil-moisture conditions enhanced the interflow of bromide tracer in water early in the experiments; but the initially dry soil-moisture conditions caused major early tracer loss to deep percolation. In one experiment, temperature of the water applied was ∼11.0°C cooler than for the other experiments. This resulted in relatively less infiltration and increased runoff of both water and bromide. Estimates of the plot surface area contributing to interflow indicated that the water and tracer came primarily from an average distance of only 1.3 m upslope from the outlet faces. These values were in close agreement with theoretical values for steady flow conditions. These results indicated a prospect for controlling the transport of chemicals in interflow, and runoff by appropriate management methods near the outlet.
Publication Year: 1985
Publication Date: 1985-02-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 26
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