Hydrodynamic characteristics of rill flow on steep slopes

Wen-ying, Peng; Zhang, Zhuodong; Zhang, Keli

doi:10.1002/hyp.10461

Cited by 66 publications

(70 citation statements)

References 28 publications

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“…Under the condition of rainfall intensities kept the same, the Froude numbers increased with higher slope gradients, and this relationship became more obvious on steeper slopes. Our results are different with other findings (Guo et al, 2013;Peng et al, 2015;Zhang et al, 2002) which both Re and Fr are greater than our values. The cause of those differences may be explained by the effective input water rate (greater rainfall intensities and slope gradients) and soil type.…”

Section: Results and Discussion Flow Hydraulic Characteristicscontrasting

confidence: 99%

“…The Darcy-Weisbach friction coefficients did not show a definitive relationship with Reynolds numbers. Our results agree with other findings (Nearing et al, 1997;Peng et al, 2015;Zhang et al, 2014) which indicated that the Reynolds number was not a good predictor of hydraulic roughness on hillslope. Furthermore, the date from our experiments indicated that the Darcy-Weisbach friction coefficients are primarily influenced by slope gradient.…”

Section: Results and Discussion Flow Hydraulic Characteristicssupporting

confidence: 91%

“…Moreover, most of the previous studies are concerned with hydraulic properties of shallow flow (Zhang et al, 2002) and hydrodynamic characteristics of rill flow on steep slopes (Peng et al, 2015;Wang et al, 2015) and runoff hydraulic characteristics in rill erosion (Li et al, 2008;Rafael and Gerard, 2008). But the hydrological processes and the associated erosional responses are known to be related to soil properties (Kinnell and Cummings, 1993).…”

Section: Introductionmentioning

confidence: 99%

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Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

Feng

Cheng

Ding

et al. 2016

Journal of Hydrology and Hydromechanics

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Hydrological processes play important roles in soil erosion processes of the hillslopes. This study was conducted to investigate the hydrological processes and the associated erosional responses on the purple soil slope. Based on a comprehensive survey of the Wangjiaqiao watershed in the Three Gorges Reservoir, four typical slope gradients (5°, 10°, 15°and 20°) were applied to five rainfall intensities (0.6, 1.1, 1.61, 2.12 and 2.54 mm·min -1 ). The results showed that both surface and subsurface runoff varied greatly depending on the rainfall intensity and slope gradient. Surface runoff volume was 48.1 to 280.1 times of that for subsurface runoff. The critical slope gradient was about 10°. The sediment yield rate increased with increases in both rainfall intensity and slope gradient, while the effect of rainfall intensity on the sediment yield rate was greater than slope gradient. There was a good linear relationship between sediment yield rate and Reynolds numbers, flow velocity and stream power, while Froude numbers, Darcy-Weisbach and Manning friction coefficients were not good hydraulic indicators of the sediment yield rate of purple soil erosion. Among the three good indicators (Re, v and w), stream power was the best predictor of sediment yield rate (R 2 = 0.884). Finally, based on the power regression relationship between sediment yield rate, runoff rate, slope gradient and rainfall intensity, an erosion model was proposed to predict the purple soil erosion (R 2 = 0.897). The results can help us to understand the relationship between flow hydraulics and sediment generation of slope erosion and offer useful data for the building of erosion model in purple soil.

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Section: Results and Discussion Flow Hydraulic Characteristicscontrasting

confidence: 99%

Section: Results and Discussion Flow Hydraulic Characteristicssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

Feng

Cheng

Ding

et al. 2016

Journal of Hydrology and Hydromechanics

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“…13). However, in the following stage, there was no obvious variation trend that could be determined as the flow discharge increased, while flow vellocity usually increased with increasing flow discharge in slope erosion (Jiang et al, 2018;Peng, Zhang, & Zhang, 2015). However, in the following stage, there was no obvious variation trend that could be determined as the flow discharge increased, while flow vellocity usually increased with increasing flow discharge in slope erosion (Jiang et al, 2018;Peng, Zhang, & Zhang, 2015).…”

Section: Sediment Dischargementioning

confidence: 94%

The impact of flow discharge on the hydraulic characteristics of headcut erosion processes in the gully region of the Loess Plateau

Shi

Wang

Chen

et al. 2019

Hydrological Processes

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Headcut erosion is associated with major hydraulic changes induced by the gully head of concentrated flow. However, the variation in the hydraulic characteristics of the headcut erosion process is still not clear in the gully region of the Loess Plateau.A series of rainfall combined scouring experiments (flow discharges ranging from 3.6 to 7.2 m 3 hr −1 , with 0.8 mm min −1 rainfall intensity) were conducted on experimental plots to clarify the variation in the hydraulic parameters induced by gully head and erosion processes under different flow discharges. The results showed that concentrated flows in the catchment area and gully bed were turbulent (Reynolds number ranging from 1,876 to 6,693) and transformed between supercritical and subcritical (Froude number ranging from 0.96 to 3.73). The hydraulic parameters, such as the flow velocity, Reynolds number, shear stress, stream power, Darcy-Weisbach friction factor, and unit stream power in the catchment area were 0.45-0.59 m s −1 , 2086-6693, 1.96-5.33 Pa, 0.89-2.86 W m −2 , 0.08-0.16, and 0.023-0.031 m s −1 ,respectively. When the concentrated flows dropped from the gully head, the hydraulic parameters in the gully bed decreased by 3., respectively, which contributed to the flow energy consumption at the gully head. As flow discharge increased, Reynolds number, shear stress, and stream power increased, while flow velocity, Froude number, unit stream power, and Darcy-Weisbach friction factor did not. The flow energy consumption at the gully head was 9. 66-10.13, 13.25-13.74, 15.68-16.41, and 19.28-20.25 J s −1 , respectively, under different flow discharges and accounted for 60.58-68.50% of the flow energy consumption of the experimental plots. Generally, the sediment discharges increased rapidly at the initial stage, then increased slowly, and finally reached a steady state condition, which showed a significant declining logarithmic trend with experimental duration (P<.01) and increased with increasing flow discharge. Accordingly, the flow energy consumption was significantly correlated with the sediment yield. These findings could improve our understanding of the hydraulic properties and flow energy characteristics of headcut erosion.

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“…Peng et al, 2015;Di Stefano et al, 2018). The first step to a better description of hydraulics in rills is to carry out a comprehensive characterization of rill bed geometry under various conditions and to identify the (role of the) controlling factors.…”

Section: Introductionmentioning

confidence: 99%

In‐situassessment of the spatial arrangement of step–pool units on eroded rills

Giménez

Zubieta

Govers

et al. 2019

Earth Surf Processes Landf

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Rills are generated on homogeneous hillslopes by the action of different discharges and evolve morphologically over short timescales due to a strong interaction between the flow and bed morphology. Such an interaction generates a reconfiguration of the bed geometry. Previous works suggest that bed geometry is often characterized by alternation between pools and flat reaches (steps). Each step–pool unit may contribute to hydraulic resistance and affects flow behaviour. The objectives of this work are (i) to assess different (innovative) techniques for the in‐situ assessment of rill bed geometry, (ii) to use these techniques to assess the geometry of eroded rills in situ in order to determine the spatial arrangement in the bed macro‐scale roughness and (iii) finally to analyse the role of slope and discharge as driving factors associated with the development of these macroforms. Roughly rectilinear, long rills were formed in the field as a result of combining different slope and discharges. Photogrammetry provided detailed digital elevation models (DEMs) before and after the experiments. The rills were morphologically characterized from the DEMs. In each rill, the presence of step–pools was identified from long profiles according mainly to morphological criteria published elsewhere, but with ad hoc critical threshold values more appropriate for small eroded channels. The minimum slope required for the development of step–pool units seems to be somewhere between 5 and 15%. Discharge seems to affect pool size or roughness amplitude. There does not seem to be a clear step–pool periodicity. However, external factors could have affected the normal growth and alternation of these structures. Identification of steps and pools from longitudinal elevation profiles can be objectively accomplished using a series of geometric rules originally proposed for rivers and large channels, and adapted to rills. © 2019 John Wiley & Sons, Ltd.

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Hydrodynamic characteristics of rill flow on steep slopes

Cited by 66 publications

References 28 publications

Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

The impact of flow discharge on the hydraulic characteristics of headcut erosion processes in the gully region of the Loess Plateau

In‐situassessment of the spatial arrangement of step–pool units on eroded rills

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