A model of the sand transport rate that accounts for temporal evolution of the bed

Wang, Xuesong; Zou, Xueyong

doi:10.1016/j.geomorph.2021.107616

Cited by 4 publications

(3 citation statements)

References 34 publications

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“…A gobi surface is a representative example because the lack of erodible sediment makes it extremely difficult to entrain enough particles to achieve saturation. Although the sand particles on the surface are all erodible at a certain wind velocity, it becomes difficult for the sand flow to become saturated because of the development of surface microtopography in the form of ripples (Wang & Zhang, 2021;Wang et al, 2020). These bedforms, in turn, extract some of the wind's momentum (Lancaster et al, 2010;MacKinnon et al, 2004).…”

Section: Index For the Saturation Level Of The Sand Flowmentioning

confidence: 99%

“…Considering the significance of sand transport in aeolian geomorphology and wind erosion, numerous studies have attempted to develop sand transport models for flat sand beds (Bagnold, 1941; Kawamura, 1951; Kok & Renno, 2009; Lettau & Lettau, 1978; Owen, 1964; Zingg, 1953). Researchers have compared their model predictions (Iversen & Rasmussen, 1999; Kok & Renno, 2009) and conducted field measurements (Wang et al, 2021) of the mass flux during sand transport to verify the model results. Sherman and Li (2012) found that the rates of sand transport predicted by various models poorly matched both the field observations and the predictions of other models.…”

Section: Introductionmentioning

confidence: 99%

“…As an extreme example, sand flow over a gobi surface rarely reaches the saturation state because there are generally insufficient erodible surface particles. However, most studies (e.g., Strypsteen et al, 2021;Tan et al, 2016;Wang & Zhang, 2021) did not explain whether the measured sand flow reached saturation or not, and instead simply assumed that the sand flow was saturated. In some cases, researchers treated the sand flow as saturated because it had reached equilibrium.…”

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confidence: 99%

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Field investigation of the fetch effect and essential conditions for saturated sand flow

Zhang

Wang

Zou

et al. 2022

Earth Surf Processes Landf

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Several models of classical aeolian sand transport mechanism have been developed to predict the rate of sand transport. However, the values predicted through modeling almost always display large and significant differences from the measured values. The reason for such discrepancies is not fully understood. By studying the effects of wind velocities and fetch lengths on the C values in the model proposed by Lettau and Lettau in 1978, we found that the saturation level of the measured sand flow can significantly affect the accuracy of the predicted value. To solve this problem, we introduced an index (δ) to represent the saturation level. The closer the δ value is to 1, the greater the chance that the sand flow is saturated. This new approach only requires measurement of the saturated sand flow data to verify the robustness of the aeolian sand transport model, a step that has been neglected by previous researchers. Our results suggest that the value of C = 6.7 proposed in the Lettau and Lettau model is sound and reliable if the sand flow is saturated. We proposed the conditions required for the sand flow to reach saturation and generated an equation to predict the sand transport saturation length (Lsat). Accordingly, we estimated Lsat to be approximately 92 m when u* = 0.47 m s−1 for the studied sand surface, which is also the minimum wind shear velocity at which the sand flow can potentially reach saturation.

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Section: Index For the Saturation Level Of The Sand Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Field investigation of the fetch effect and essential conditions for saturated sand flow

Zhang

Wang

Zou

et al. 2022

Earth Surf Processes Landf

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Separating emitted dust from the total suspension in airflow based on the characteristics of PM10 vertical concentration profiles on a Gobi surface in northwestern China

et al. 2022

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During aeolian processes, the two most critical factors related to dust emissions are soil particle and aggregate saltation, which greatly affect the vertical profiles of near-surface dust concentrations. In this study, we measured PM10 concentrations at four different heights (0.10, 0.50, 1.00 and 2.00 m) with and without continuous and simultaneous aeolian saltation processes on a Gobi surface in northwestern China from 31 March to 10 April, 2017. We found that the vertical concentration profiles of suspended PM10 matched the log-law model well when there was no aeolian saltation. For the erosion process with saltation, we divided the vertical concentration profiles of PM10 into the saltation-affected layer and the airflow-transport layer according to two different dust sources (i.e., locally emitted PM10 and upwind transported PM10). The transition height between the saltation-affected layer and the airflow-transport layer was not fixed and varied with saltation intensity. From this new perspective, we calculated the airflow-transport layer and the dust emission rate at different times during a wind erosion event occurred on 5 April 2017. We found that dust emissions during wind erosion are primarily controlled by saltation intensity, contributing little to PM10 concentrations above the ground surface compared to PM10 concentrations transported from upwind directions. As erosion progresses, the surface supply of erodible grains is the most crucial factor for saltation intensity. When there was a sufficient amount of erodible grains, there was a significant correlation among the friction velocity, saltation intensity and dust emission rate. However, when supply is limited by factors such as surface renewal or an increase in soil moisture, the friction velocity will not necessarily correlate with the other two factors. Therefore, for the Gobi surface, compared to limiting dust emissions from upwind directions, restricting the transport of suspended dust in its path is by far a more efficient and realistic option for small areas that are often exposed to dust storms. This study provides some theoretical basis for correctly estimating PM10 concentrations in the Gobi areas.

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Soil wind erosion rate on rough surfaces: A dynamical model derived from an invariant pattern of the shear-stress probability density function of the soil surface

Zou¹,

Li²,

Kang³

et al. 2022

CATENA

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A model of the sand transport rate that accounts for temporal evolution of the bed

Cited by 4 publications

References 34 publications

Field investigation of the fetch effect and essential conditions for saturated sand flow

Field investigation of the fetch effect and essential conditions for saturated sand flow

Separating emitted dust from the total suspension in airflow based on the characteristics of PM10 vertical concentration profiles on a Gobi surface in northwestern China

Soil wind erosion rate on rough surfaces: A dynamical model derived from an invariant pattern of the shear-stress probability density function of the soil surface

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