Experimental study on the correction factor of surface overland flow velocity

Li, Pu; Zhang, Kuandi; Xu, Qiangqiang; Lv, Xiangru; Ling, Peng; Cen, Youdong; Shang, Haixin

doi:10.1016/j.catena.2022.106576

Cited by 8 publications

(5 citation statements)

References 28 publications

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“…For laminar flow, as expected, the mean α value of SD (0.31) and ST (0.37) is significantly less than Horton's theoretical value of 0.67 (Horton et al, 1934) (Table 4). The α value of SD (0.31) is similar to the observed α value (0.32) of Pan et al (2015) and Li et al (2022), but lower than the α value (0.53) of Emmett (1970). Moreover, the α value of ST (0.37) is similar to the observed α value (0.35) given by Polyakov et al (2021) on rough natural plots with rocks, but lower than the α value (tile: 0.56, litter: 0.54) reported by Dunkerley (2001).…”

Section: Discussionsupporting

confidence: 83%

Section: Predictive Equations Of Correction Factor αsupporting

confidence: 70%

“…Mean velocity of overland flow is one of the most important hydraulic variables, and it is used to determine the erosivity and transport capacity of overland flow in physically based soil erosion models (Abrahams et al, 1986; Li et al, 2022; Polyakov et al, 2021; Takken & Govers, 2000). Furthermore, it is also crucial for the estimation of hydraulic characteristics, such as friction coefficient, stream power and unit stream power (Zhang et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…In other words, the presence of roughness elements results in more complicated velocity fields that vary spatially and temporally under different inundation conditions, thereby modifying the form of the vertical velocity profile as well as the α value. In the past, the majority of previous investigations have focused on determining the α value for various rough surfaces (Li & Abrahams, 1997; Li et al, 2022; Nicosia et al, 2021; Phelps, 1975). However, little is known about how α varies with progressive inundation conditions, including both non‐submerged and submerged flow, especially for rough surfaces with protruding roughness elements (e.g., stones).…”

Section: Introductionmentioning

confidence: 99%

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Correction factor for determining mean velocity of shallow flow on rough surfaces under varying inundation conditions using dye tracer method

Fan

Jia

et al. 2023

Earth Surf Processes Landf

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Accurate estimation of mean flow velocity is crucial for hydraulics and soil erosion studies. A correction factor (α) is required to convert flow surface velocity to mean velocity when using the dye tracer method. However, the determination of an appropriate α value is challenging and little information is available about how α varies with progressive inundation conditions, especially for rough surfaces with protruding roughness elements (e.g., stones). Therefore, laboratory experiments were conducted in a flume with sandpaper (SD) and stones (ST) surfaces to investigate the impact of roughness elements on the correction factor with varying inundation conditions. The results showed that using a single α value is inappropriate for rough surfaces. The correction factor was positively correlated with the Reynolds number and is controlled by flow regimes as well. Moreover, the impacts of inundation conditions as well as protruding roughness elements should be taken into account for determining α. Correction factor varied non‐monotonically with inundation ratio, depending on the progressive inundation status of protruding roughness elements. The developed equations introducing the inundation ratio performed well in predicting α, with R2 = 0.86 and NSE = 0.91. The results contribute to our understanding of measuring mean flow velocity using the dye tracer method.

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Section: Discussionsupporting

confidence: 83%

Section: Predictive Equations Of Correction Factor αsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Correction factor for determining mean velocity of shallow flow on rough surfaces under varying inundation conditions using dye tracer method

Fan

Jia

et al. 2023

Earth Surf Processes Landf

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“…Li et al (2022) performed overland flow experiments testing the effects of six surface roughness values, five rainfall intensities, 10 grass cover densities and three grass‐shrub communities on the correction factor. For smooth surfaces, they found a negative correlation between α v and the slope gradient (ranging from 8.7% to 42.26%) and no significant influence of Re on α v .…”

Section: Introductionmentioning

confidence: 99%

On the variation of the correction factor of surface velocity with the measurement vertical for shallow flows over rough beds

Carollo

Nicosia

Palmeri

et al. 2023

Hydrological Processes

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Considering that water flow energy affects the detachment of soil particles, the transport and deposit of the detached particles, the flow velocity is a key variable governing the soil erosion processes at the hillslope scale. The simple dye-tracer technique for measuring mean flow velocity can be applied in non-controlled field applications for which some measurement difficulties (e.g. due to sediment transport, and shallow flows) can occur. The correction factor is usually obtained as the ratio between the mean velocity, deriving from measurements of flow discharge and water depth, and surface velocity. Alternatively, the possibility of using the velocity profile in a given vertical to determine a suitable correction factor has not yet been explored. In this article, the flow velocity measurements were carried out in five verticals having a different distance from the wall of a flume whose bed was covered by hemispheres with different concentrations (9%-64%) and organized in two arrangements (square, staggered). Fifteen runs, characterized by different Reynolds and Froude numbers, were performed and the correction factor α vv was calculated for each vertical. For the axial vertical α vv was independent of the arrangement, decreased with the hemisphere concentration, and increased with both the Froude and Reynolds numbers. Furthermore, α vv decreased from the bank to the flume axis as a result of the varying shape of the velocity profile. The analysis showed that the frequency distributions of the ratio between α vv and its mean value α m were overlaid and α m was used to represent the correction factor, accordingly. A relation of α m with the distance from the flume wall was detected. For the measured velocity profiles having a power shape, the analysis also demonstrated that the α vv values, obtained by fitting the power law to the measurements, were close to both those calculated as the ratio between the mean velocity along the vertical and the surface velocity and their averaged values across the hydraulic section. These three methods give comparable average values of the correction factor, in the range of

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An Experimental Study on the Effects of Sediment Particle Characteristics on the Flow Velocity Correction Factor for Runoff in Steep Nonerodible Rills

Zhang,

Tao,

et al. 2024

Hydrological Processes

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Flow velocity is a key hydraulic variable in the exploration of rill erosion and is usually estimated by multiplying the surface flow velocity of runoff (measured with the dye tracer method) by the flow correction factor (a). However, there are differences among different experimental conditions, and the selection of the right value of a has become critical for accurately estimating the mean flow velocity. There has been little research on velocity correction factors for hyperconcentrated flows on steep slopes. In this study, gravel‐laden sediment (mass fraction of gravel in the sample ranging from 0% to 70%, corresponding to a median diameter of 0.08–2.95 mm) was used as the test material, and different slopes (18%–84%) and unit flow discharges (1.11–4.44 × 10−3 m2 s−1) were considered to investigate the effects of gravel‐laden sediment particle characteristics on runoff a and to elucidate the mechanism of the effects of different hydrodynamic parameters on runoff a. Under the experimental conditions, the value of a ranged from 0.285 to 0.690. a increases with increasing flow discharge and slope, with flow discharge having a greater effect than slope. With increasing gravel content and median diameter (d50), a decreased initially but then stabilised. Additionally, a decreased with increasing sediment content but increased with increasing Reynolds number (Re). Based on the results of this experiment, 0.37, 0.49 and 0.60 are recommended as the correction factors of surface flow velocity for laminar flow (Re ≤ 500), transitional flow (500 < Re ≤ 2000) and turbulent flow (Re > 2000), respectively. Equation (16), which is based on the hydraulic parameters and sediment particle characteristics, has the best accuracy (Nash–Sutcliffe efficiency coefficient [NSE] > 0.9). The research results quantified the impact of sediment particle characteristics on a, contributing to the advancement of hydrodynamic studies on rill flow.

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Experimental study on the correction factor of surface overland flow velocity

Cited by 8 publications

References 28 publications

Correction factor for determining mean velocity of shallow flow on rough surfaces under varying inundation conditions using dye tracer method

Correction factor for determining mean velocity of shallow flow on rough surfaces under varying inundation conditions using dye tracer method

On the variation of the correction factor of surface velocity with the measurement vertical for shallow flows over rough beds

An Experimental Study on the Effects of Sediment Particle Characteristics on the Flow Velocity Correction Factor for Runoff in Steep Nonerodible Rills

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