Quantifying detachment rate of eroding rill or ephemeral gully for WEPP with flume experiments

Zhang, Qingwen; Dong, Yuequn; Li, Fang; Zhang, Aiping; Lei, Tingwu

doi:10.1016/j.jhydrol.2014.09.040

Cited by 36 publications

(17 citation statements)

References 33 publications

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“…Many other studies (in situ and in vitro) have also shown that stream power is better than other parameters. Although the hydraulic and erodibility values in this study were within the range of the reported values by the previous studies (Nearing et al, 1999;Knapen et al, 2007;Zhang et al, 2014), the erodibility and threshold values of unit stream power had not been confirmed by the WEPP, EUROSEM, and EGEM models (Zhang et al, , 2014Tekwa et al, 2015). Together with previous findings (Zhang et al, , 2014, it is claimed that more efforts should be made to further investigate the mechanisms of soil erosion and improve erosion models.…”

Section: Discussioncontrasting

confidence: 75%

“…However they suggested that more field-based experiments are necessary to effectively analyse effects of land use changes on the threshold situation of head cut initiation. In addition, most physically based erosion models such as WEPP, CREAMS, and PRORILL are based on the simplified transport capacity equation (Yalin, 1977) and soil detachment rate as well as shear stress (Zhang et al, 2014). These models predict the soil erosion through the rill and inter-rill concept while neglecting gully erosion distribution along a catchment.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of land use impact on hydraulic threshold conditions for gully head cut initiation

Samani

Chen

Khalighi

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. A gully as an accelerated erosion process is responsible for land degradation under various environmental conditions and has been known as a threshold phenomenon. Although the effects of gullying processes have been well documented, few soil erosion models have taken into account the threshold condition necessary for gully development. This research was devoted to determining the effects of land use change on hydraulic threshold condition and stream power of water flow through an in situ experimental flume (15 m × 0.4 m). Results indicated that head cut initiation and detachment rates showed a better correlation to stream power indices than shear stress (τ cr ). The threshold unit stream power value (ω u ) for head cut initiation in rangeland, abandoned land, and dry farming land was 0.0276, 0.0149, and 4.5 × 10 −5 m s −1 , respectively. Moreover, the micro-relief condition of soil surface and surface vegetation affected the flow regime of discharge and velocity. It is seen that the composite hydraulic criteria of Froude number (Fr) and discharge (Q) can clearly discriminate the land uses' threshold. In fact, the remarkable decrease of τ cr in dry farming was related to the effect of tillage practice on soil susceptibility and aggregate strength. The findings indicated that using the unit steam power index instead of critical shear stress could increase the models' precision for prediction of head cut development. Compared to the Ephemeral Gully Erosion Model (EGEM) equation for critical shear stress, it is important to point out that for modelling of gully erosion, using single soil attributes can lead to an inaccurate estimation for τ cr . In addition, based on the findings of this research, the use of threshold values of τ cr = 35 dyne cm −2 and ω u = 0.4 cm s −1 in physically based soil erosion models is susceptible to high uncertainty when assessing gully erosion.

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Section: Discussioncontrasting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Assessment of land use impact on hydraulic threshold conditions for gully head cut initiation

Samani

Chen

Khalighi

et al. 2016

Hydrol. Earth Syst. Sci.

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“…ALT is suggested to be at least four times higher than the MEL value (Van De Wiel et al , ). We found that a higher MEL value was needed to simulate a more rapid change with high sediment yield, which is more representative of ephemeral channels and short‐temporal scale (Vanwalleghem et al , ; Hancock et al , ; Zhang et al , ).…”

Section: Discussionsupporting

confidence: 88%

Using a landform evolution model to study ephemeral gullying in agricultural fields: the effects of rainfall patterns on ephemeral gully dynamics

Hoober

Svoray

Cohen

2017

Earth Surf Processes Landf

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Water driven soil erosion is a major cause of land degradation worldwide. Ephemeral gullies (EGs) are considered key contributors to agricultural catchment soil loss. Despite their importance, the parameters and drivers controlling EG dynamics have not been adequately quantified. Here we investigate the effects of rainfall characteristics on EGs, using the physically based landform evolution model (LEM) CAESAR‐Lisflood. An initial goal of this study was to test the feasibility of using a LEM to estimate EG dynamics based on an easily obtainable and moderate spatial resolution (2 × 2 m) Digital Elevation Model (DEM). EG evolution was simulated for two rainfall seasons in a 0.37 km2 agricultural plot situated in a semiarid catchment in central Israel. The 2014 rainfall season was used to calibrate the model and the 2015 season was used for validation. The model overall well predicted the EG network structure and average depth but tended to underestimate the EG length. The effects of rainfall characteristics on EG dynamics were investigated by comparing simulations employing seven rainfall scenarios. Four of these scenarios differ in their overall rainfall volume relative to observed precipitation (+20%, +10%, −10%, −20%). The remaining three scenarios vary in the temporal distribution of rainfall during each storm, allowing us to isolate the effect of rainfall intensity on EG evolution. The results show that: (1) EG dynamics strongly correlated with changes in rainfall volume; (2) small‐scale morphological behavior varies between rainfall scenarios, resulting in different meandering and connectivity variability; (3) EG evolution is divided into two main stages, an initial rapid development occurring after the first two weeks of the rainy season, followed by a stable development period; (4) a 12 mm h−1 intensity threshold was observed to initiate and, later, modify EGs; and (5) inner storm rainfall variability can have a considerable effect on EG evolution. Copyright © 2016 John Wiley & Sons, Ltd.

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“…Shear stress mainly reflects the effect of concentrated flow on the eroded slope surface as rills begin to form, and the effect of sidewall slumping and head‐cutting are not explicitly modelled (Mahmoodabadi, Ghadiri, Yu, & Rose, ). Flow energy, which expressed the energy of runoff water expenditure on the soil surface per unit bed area (stream power) or per unit mass of water (unit stream power), were able to reflect the effects of these subprocess by altering the distribution of the energy for detachment and transport of soil materials (Foster, Meyer, & Onstad, ; Zhang et al, ). However, the energy term of unit energy of water‐carrying section performs worse than the hydraulic term of shear stress in representing the soil detachment rate.…”

Section: Discussionmentioning

confidence: 99%

“…The direct and indirect effects of soil erosion slow down the socioeconomic and environmental development in this region (Liu, Liu, et al, ). Loessial soil is one of the most erodible soil types, and the high silt content makes it susceptible to detachment and transport by concentrated flow (Zhang, Dong, Li, Zhang, & Lei, ). A rill is a small, intermittent watercourse with steep sides and usually only several centimetres deep (Soil Science Society of America, ).…”

Section: Introductionmentioning

confidence: 99%

Response of soil detachment rate to the hydraulic parameters of concentrated flow on steep loessial slopes on the Loess Plateau of China

Xiao

Liu

et al. 2017

Hydrological Processes

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Using hydraulic parameters is essential for describing soil detachment and developing physically based erosion prediction models. Many hydraulic parameters have been used, but the one that performs the best for describing soil detachment on steep slopes when the lateral expansion (widening) of rills is not limited has not been identified. An indoor concentrated flow scouring experiment was performed on steep loessial slopes to investigate soil detachment rates for different flow rates and slope gradients. The experiments were conducted on a slope‐adjustable plot (5 m length, 1 m width, 0.5 m depth). Sixteen combinations of 4 flow rates (10, 15, 20, and 25 L/min) and 4 slope gradients (17.6%, 26.8%, 36.4%, and 46.6%) were investigated. The individual and combined effects of slope gradient and flow hydraulic parameters on soil detachment rate were analysed. The results indicated that soil detachment rate increased with flow rate and slope gradient. Soil detachment rate varied linearly and exponentially with flow rate and slope gradient, respectively. Multivariate, nonlinear regression analysis indicated that flow depth exerted the greatest influence on the soil detachment rate, followed by unit discharge per unit width, slope gradient, and flow rate in this study. Shear stress and stream power could efficiently describe the soil detachment rate using a power equation. However, the unit stream power and unit energy of the water‐carrying section changed linearly with soil detachment rate. Stream power was an optimal hydraulic parameter for describing soil detachment. These findings improve our understanding of concentrated flow erosion on steep loessial slopes.

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Quantifying detachment rate of eroding rill or ephemeral gully for WEPP with flume experiments

Cited by 36 publications

References 33 publications

Assessment of land use impact on hydraulic threshold conditions for gully head cut initiation

Assessment of land use impact on hydraulic threshold conditions for gully head cut initiation

Using a landform evolution model to study ephemeral gullying in agricultural fields: the effects of rainfall patterns on ephemeral gully dynamics

Response of soil detachment rate to the hydraulic parameters of concentrated flow on steep loessial slopes on the Loess Plateau of China

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