Slope–velocity equilibrium and evolution of surface roughness on a stony hillslope
Author
Nearing, Mark A.Polyakov, Viktor O.
Nichols, Mary H.
Hernandez, Mariano
Li, Li
Zhao, Ying
Armendariz, Gerardo
Affiliation
Univ Arizona, Sch Nat Resources & EnvironmIssue Date
2017-06-30
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COPERNICUS GESELLSCHAFT MBHCitation
Slope–velocity equilibrium and evolution of surface roughness on a stony hillslope 2017, 21 (6):3221 Hydrology and Earth System SciencesRights
© Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Slope–velocity equilibrium is hypothesized as a state that evolves naturally over time due to the interaction between overland flow and surface morphology, wherein steeper areas develop a relative increase in physical and hydraulic roughness such that flow velocity is a unique function of overland flow rate independent of slope gradient. This study tests this hypothesis under controlled conditions. Artificial rainfall was applied to 2 m by 6 m plots at 5, 12, and 20 % slope gradients. A series of simulations were made with two replications for each treatment with measurements of runoff rate, velocity, rock cover, and surface roughness. Velocities measured at the end of each experiment were a unique function of discharge rates, independent of slope gradient or rainfall intensity. Physical surface roughness was greater at steeper slopes. The data clearly showed that there was no unique hydraulic coefficient for a given slope, surface condition, or rainfall rate, with hydraulic roughness greater at steeper slopes and lower intensities. This study supports the hypothesis of slope–velocity equilibrium, implying that use of hydraulic equations, such as Chezy and Manning, in hillslope-scale runoff models is problematic because the coefficients vary with both slope and rainfall intensity.Note
Open Access JournalISSN
1607-7938Version
Final published versionAdditional Links
https://www.hydrol-earth-syst-sci.net/21/3221/2017/ae974a485f413a2113503eed53cd6c53
10.5194/hess-21-3221-2017
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Except where otherwise noted, this item's license is described as © Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License.