Slope–velocity equilibrium and evolution of surface roughness on a stony hillslope
AuthorNearing, Mark A.
Polyakov, Viktor O.
Nichols, Mary H.
AffiliationUniv Arizona, Sch Nat Resources & Environm
MetadataShow full item record
PublisherCOPERNICUS GESELLSCHAFT MBH
CitationSlope–velocity equilibrium and evolution of surface roughness on a stony hillslope 2017, 21 (6):3221 Hydrology and Earth System Sciences
Rights© Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License.
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AbstractSlope–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.
NoteOpen Access Journal
VersionFinal published version