Rill flow velocity affected by the subsurface water flow depth of purple soil in Southwest China

Subsurface water flow above the weakly permeable soil layer commonly occurs on purple soil slopes. However, it remains difficult to quantify the effect of subsurface water flow on the surface flow velocity. Laboratory experiments were performed to measure the rill flow velocity on purple soil slopes...

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Bibliographic Details
Published in:Journal of mountain science 2022-03, Vol.19 (3), p.704-714
Main Authors: Tao, Ting-ting, Chen, Shi-qi, Chen, Xiao-yan
Format: Article
Language:English
Subjects:
Earth and Environmental Science
Earth Sciences
Ecology
Electrolytes
Environment
Flow rates
Flow velocity
Geography
Hydrology
Original Article
Saturated soils
Slope gradients
Soil
Soil layers
Soil permeability
Subsurface water
Surface flow
Tracers
Transport processes
Velocity
Water depth
Water flow
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Summary:Subsurface water flow above the weakly permeable soil layer commonly occurs on purple soil slopes. However, it remains difficult to quantify the effect of subsurface water flow on the surface flow velocity. Laboratory experiments were performed to measure the rill flow velocity on purple soil slopes containing a subsurface water flow layer with the electrolyte tracer method considering 3 subsurface water flow depths (SWFDs: 5, 10, and 15 cm), 3 flow rates (FRs: 2, 4, and 8 L min −1 ), and 4 slope gradients (SGs: 5°, 10°, 15°, and 20°). As a result, the pulse boundary model fit the electrolyte transport processes very well under the different SWFDs. The measured rill flow velocities were 0.202 to 0.610 m s −1 under the various SWFDs. Stepwise regression results indicated a positive dependence of the flow velocity on the FR and SG but a negative dependence on the SWFD. The SWFD had notable effects on the rill flow velocity. Decreasing the SWFD from 15 to 5 cm increased the flow velocity. Moreover, the flow velocities under the 10- and 15-cm SWFDs were 89% and 86%, respectively, of that under the 5-cm SWFD. The flow velocity under the 5-, 10- and 15-cm SWFDs was decreased to 89%, 80%, and 77%, respectively, of that on saturated soil slopes. The results will enhance the understanding of rill flow hydrological processes under SWFD impact.
ISSN:1672-6316
1993-0321
1008-2786
DOI:10.1007/s11629-021-7252-y