Apportioning contributions of individual rill erosion processes and their interactions on loessial hillslopes

Qin, Chao; Wilson, George Grafton; Zhang, X. C.; Xu, Ximeng

doi:10.1016/j.catena.2019.104099

Cited by 28 publications

(10 citation statements)

References 48 publications

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“…Based on the erosive rainfall characteristics of the study area (Zhou and Wang, 1987), two representative rainfall intensities of 50 and 100 mm h –1 were applied to a soil pan (i.e. 10.0 m × 3.0 m × 0.5 m, length × width × height), which was set at a typical slope of 20° (Qin et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

Rill network development on loessial hillslopes in China

Shen

Zheng

Zhang

2020

Earth Surf Processes Landf

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Rill network development not only potentially affects hillslope and drainage network evolution, but also causes severe soil degradation. However, the studies on rill network development remain inconclusive. This study aimed to investigate the temporal and spatial development of hillslope rill networks and their characteristics based on rainfall simulations and field observations. A soil pan (10.0m long × 3.0m wide × 0.5m deep) on a 20°slope was applied three successive simulated rains at two intensities of 50 and 100mmh-1. The field observations were performed on two bare hillslope runoff plots (10.0m long × 3.0m wide) at 20°. Three typical erosive natural rainfall events were observed in the field, and rills were measured in detail, similar to the laboratory rainfall simulation. The results indicated that with increases in rainfall events, the rill network morphology varied from incipient formation to the maximum drainage network density. Four rill network development indicators (rill distribution density, distance between rills, rill bifurcation number, and confluence point number) exhibited different changes over time and space. Among the four indicators, the rill bifurcation number was the best indicator for describing rill network development. Rill flow energy increased and decreased cyclically on a slope ranging between~3 and 4m. Moreover, rill networks on loessial hillslopes generally evolved into dendritic rather than parallel forms. The development characteristics of the rill network were relatively similar between the laboratory simulation and natural field conditions. Over time, rill erosion control measures become increasingly difficult to implement as the rill network develops. The morphology of eroding rills evolved over time and space, which led to corresponding rill network development. Further study should quantify the impacts of rill network development on soil degradation and land development.

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Section: Methodsmentioning

confidence: 99%

Rill network development on loessial hillslopes in China

Shen

Zheng

Zhang

2020

Earth Surf Processes Landf

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“…They observed for all runoff events that the SSC was highest at the initial surge of flash floods and decreased monotonically with timewith SSC values that were orders of magnitude higherafter fires. It has been observed in channel flows, both in controlled laboratory studies (Qin et al, 2019) and field conditions (Midgley et al, 2013), that mass failures of channel banks provide sediment in the flow channel that is easily dispersed and suspended for transport in subsequent flow events. Several studies (Rinaldi and Casagli, 1999;Fox et al, 2007;Wilson et al, 2007) have noted that bank failures tend to occur during the recession limb of the hydrograph, thus there can be an abundance of sediment available at the start of a flow event.…”

Section: Suspended Sediment Responsesmentioning

confidence: 99%

Internal erosion of soil pipes: Sediment rating curves for soil pipes

Wilson

Ursic

Fox

et al. 2020

Earth Surf Processes Landf

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The collapse of soil pipes due to internal erosion can result in fully mature gullies. Few studies have measured the rates of sediment detachment and transport through soil pipes in situ. The objectives of this work were to determine suspended sediment concentration (SSC) in soil pipes as a function of pipeflow rate to develop sediment rating curves (SRC) and measure the bedload transport as a function of cumulative flow per storm event. H‐flumes were installed in seven discontinuous gullies formed by pipe collapse and instrumented for pipe discharge measurements and suspended sediment sampling. The typical response to pipeflow was an initial flush of high concentration of suspended sediment followed by a decrease as pipeflow increased (rising limb of hydrograph). Pipeflows were often so dynamic that it was difficult to consistently capture the initial flush of sediment, resulting in weak to non‐existent SRCs. The falling limb of the hydrograph tended to have a relatively low SSC. Thus, soil pipe SRCs tended to be better represented by hysteretic SRCs, although relationships between SSC and flow rate were poorly represented by SRCs. A power law equation given by SSC = aQb was adopted to represent the SRC relationships. Fitting this equation to data showed a correlation between the offset, a, and the slope, b, with the slope decreasing as the offset increases. Both SRC parameters (a and b) were correlated to the contributing area of the individual pipe. Bedload appeared to be an important contributor to sediment transport, with bedload – expressed as an average event sediment concentration (mg l−1) – decreasing as the volume of the event discharge (m3) increased. A significant portion (11–31%) of the bedload material was gravel and aggregates (>2 mm diameter material). While this work was the first to determine SRCs for soil pipes, refined sampling and measurement techniques are needed. © 2020 John Wiley & Sons, Ltd.

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“…Based on the time for rill occurrence, rill erosion processes is grouped into ve stages: knick points, headcut extension, intermittent rill, continuous rill, and rill networks under a multi-rainfall condition (Huo et al 2011). Rill erosion also is a complex physical process that includes headcut advance, bed incision (downward scouring) and sidewall expansion (widening) (Qin et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Development of rill erosion on bare sloping farmland under natural rainfall conditions

2022

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Rill erosion is an important type of soil erosion and provide a basis for preventing and controlling soil loss on sloping farmland. This study was conducted in a standard runoff plot of bare soil (20 m length, 5 m width with a slope of 10 degrees) to monitored runoff and sediment processes during two continuous and two intermittent natural rainfall events, and observed the rill morphological characteristics after multiple rainfall conditions. We observed the runoff and sediment processes presented a pattern of multi-peaks for continuous rainfall events, and a pattern of single or two peaks during two intermittent rainfall events. The sediment yield rate with instantaneous rainfall intensity and runoff rate exhibited a peak lag phenomenon with 1-6 min. After multiple rainfall events, rill were identi ed as strip-shaped, Vshaped, and tree-branched distribution, and rills were mainly distributed in 5-20 cm width and 0-10 cm depth, and the mean rill length, width and depth increased 2.27, 0.30 and 0.16 times compared to the initial slope (R 0 ). The side-wall collapse erosion was mostly greater than downcutting erosion in the slope section I, II and III. In conclusion, this study help to understanding the slope runoff and erosion mechanisms, and provide a scienti c basis for soil erosion model on sloping farmland.

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Apportioning contributions of individual rill erosion processes and their interactions on loessial hillslopes

Cited by 28 publications

References 48 publications

Rill network development on loessial hillslopes in China

Rill network development on loessial hillslopes in China

Internal erosion of soil pipes: Sediment rating curves for soil pipes

Development of rill erosion on bare sloping farmland under natural rainfall conditions

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