Spatial distribution of sheet flow velocity along slope under simulated rainfall conditions

Zhuang, Xiaohui; Wang, Wei; Ying, Ma; Huang, Xingfa; Lei, Tingwu

doi:10.1016/j.geoderma.2018.01.036

Cited by 31 publications

(9 citation statements)

References 33 publications

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“…Simultaneously, the resistance on the slope is higher, resulting in a uniform or decelerated flow along the slope. In such scenarios, the impact of the slope on the runoff velocity is minimal [28,30,31]. The runoff velocity is directly proportional to the product of the power function of slope and the power function of rainfall intensity, consistent with earlier research findings [32].…”

Section: Shear Stress Stream Power Unit Stream Power and Unit Energysupporting

confidence: 89%

Responses of Soil and Ammonia Nitrogen Loss Rates to Hydraulic Parameters under Different Slope Gradients and Rainfall Intensities

Yang,

Wei,

Sun

et al. 2024

Water

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Soil erosion and the consequent loss of nutrients have consistently been significant factors contributing to land degradation and nonpoint source pollution. While runoff serves as the primary carrier for nutrient loss, the hydraulic processes governing the mechanisms of nutrient loss remain not entirely clear. This paper aims to investigate the impacts of rainfall intensity and the slope gradient on hydraulic parameters, soil loss rates, and ammonia nitrogen loss rates, with the objective of determining the optimal hydraulic parameters for more accurate predictions of soil erosion and nutrient loss rates. A series of simulated rainfall experiments with three rainfall intensities (25, 50, and 75 mm min−1) and four slope gradients (8.7%, 17.6%, 26.8%, and 36.4%) were conducted on a 5 m × 10 m slope. The results indicated that the flow velocity, shear stress, stream power, unit stream power, and unit energy all increased with the increase in slope gradient or rainfall intensity. The water depth decreased with an increase in the slope gradient but increased with an increase in the rainfall intensity. Laminar flow occurred in all experiments (Reynolds number < 500). Only the overland flow under a 25 mm h−1 rainfall intensity and 8.7% slope gradient was subcritical flow (Froude number < 1). Hydraulic parameters, the soil loss rate, and ammonia nitrogen loss rate could be all expressed as the product of rainfall intensity and slope power function, with R2 ranging from 0.949 to 0.997. The average soil loss rate and process soil erosion rate could both be fitted using the power function of hydraulic parameters, with the optimal fitting parameter being stream power (R2 = 0.980 and 0.909). The average ammonia nitrogen loss rate exhibited a linear relationship with the hydraulic parameters, and the optimal fitting parameter was also stream power (R2 = 0.933). However, there were relatively low correlations between hydrodynamic parameters and the ammonia nitrogen loss rate (R2 = 0.450–0587). Our results contribute to a deeper understanding of the hydraulic processes involved in nutrient loss.

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Section: Shear Stress Stream Power Unit Stream Power and Unit Energysupporting

confidence: 89%

Responses of Soil and Ammonia Nitrogen Loss Rates to Hydraulic Parameters under Different Slope Gradients and Rainfall Intensities

Yang,

Wei,

Sun

et al. 2024

Water

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“…Sediment load increased rapidly within the initial rill section on saturated soil slopes, particularly under the two steeper slopes (Figure 3). In our experiment, concentrated flow was introduced from a peristaltic pump at the upper end of the rill, and flow velocity increased with rill length until it became steady upon its maximum level (Dong, Zhuang, Lei, et al, 2014; Zhuang, Wang, Ma, et al, 2018). Under higher flow velocity, namely greater kinetic energy, more sediments can be eroded under the same flow rate and slope gradient (Huang et al, 2018).…”

Section: Discussionmentioning

confidence: 97%

Rill erosion processes on a constantly saturated slope

Huang

Wang

2020

Hydrological Processes

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Rill erosion processes on saturated soil slopes are important for understanding erosion hydrodynamics and determining the parameters of rill erosion models. Saturated soil slopes were innovatively created to investigate the rill erosion processes. Rill erosion processes on saturated soil slopes were modelled by using the sediment concentrations determined by sediment transport capacities (STCs) measurement and the sediment concentrations at different rill lengths. Laboratory experiments were performed under varying slope gradients (5°, 10°, 15°, and 20°) and unit‐width flow rates (0.33, 0.67, and 1.33 × 10−3 m3 s−1 m−1) to measure sediment concentrations at different rill lengths (1, 2, 4, and 8 m) on saturated soil slopes. The measured sediment concentrations along saturated rills ranged from 134.54 to 1,064.47 kg/m3, and also increased exponentially with rill length similar to non‐saturated rills. The model of the rill erosion process in non‐saturated soil rills was applicable to that in saturated soil rills. However, the sediment concentration of the rill flow increased much faster, with the increase in rill length, to considerably higher levels at STCs. The saturated soil rills produced 120–560% more sediments than the non‐saturated ones. Moreover, the former eroded remarkably faster in the beginning section of the rills, as compared with that on the non‐saturated soil slopes. This dataset serves as the basis for determining the erosion parameters in the process‐based erosion models on saturated soil slopes.

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“…This study revealed distinct differences in flow characteristics between homogeneous and heterogeneous slopes. On homogeneous slopes, the average velocity sequence was downsection > midsection > upsection (Figure 9), indicating that gravitational forces dominated over resistance to water flow along the slope (Zhuang et al, 2018). Moreover, greater runoff observed in the down sections, which resulted from inflow infiltration and sediment convergence, reduced the hindrances posed by the underlying surface.…”

Section: Discussionmentioning

confidence: 99%

Erosion processes and sediment source tracing on heterogeneous slopes in the red soil region of southern China

Wu,

Lei,

Luo

et al. 2024

Earth Surf Processes Landf

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Understanding erosion, sediment sources and the spatial distribution along heterogeneous slopes is essential for soil and water conservation. In this study, soils derived from nodular limestone, mud‐like limestone and limestone breccia (abbreviated as SMTL, SMDL and SLBC, respectively) were utilized to establish artificial homogeneous and heterogeneous slopes. The homogeneous slopes MTL, MDL and LBC represent SMTL‐, SMDL‐ and SLBC‐filled‐ slopes, respectively. The heterogeneous slopes were abbreviated as MTL/MDL, MDL/LBC and LBC/MTL. Rare earth elements (REEs; lanthanide, cerium and ytterbium) were used to tag soils on the upper and lower slope sections to track sediment transport and deposition. The results showed that for homogeneous slopes, the LBC slope was the most severely eroded, followed by the MDL and MTL slopes. For heterogeneous slopes, the order of erosion was LBC/MTL > MTL/MDL > MDL/LBC. Upslope sections contributed a sizable portion of the total sediment yield, ranging from 51% to 79%. Over time, the difference in the sediment contribution between the upslope and downslope regions decreased and reached equilibrium. Runoff rates on heterogeneous slopes demonstrated an inverse function (R2 > 0.75) in contrast to a logarithmic distribution (R2 > 0.87) on homogeneous slopes. Heterogeneous slopes displayed minimal intersegment variation and the absence of a consistent ordering of the magnitude of hydraulic parameters. Conversely, the hydraulic parameters of homogeneous slopes were consistently ordered across the slope sections. For sediment transport, all slopes exhibited suspension‐dominated flow with percentages greater than 89%. However, the particle size distribution of the sediment of heterogeneous slopes exhibited greater diversity and complexity because of the coexistence of distinct soils. These findings underscore the importance of customized strategies for soil and water conservation in environments characterized by diverse soil parent materials.

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Spatial distribution of sheet flow velocity along slope under simulated rainfall conditions

Cited by 31 publications

References 33 publications

Responses of Soil and Ammonia Nitrogen Loss Rates to Hydraulic Parameters under Different Slope Gradients and Rainfall Intensities

Responses of Soil and Ammonia Nitrogen Loss Rates to Hydraulic Parameters under Different Slope Gradients and Rainfall Intensities

Rill erosion processes on a constantly saturated slope

Erosion processes and sediment source tracing on heterogeneous slopes in the red soil region of southern China

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