Modeling soil erodibility and critical shear stress parameters for soil loss estimation

Recent researches were investigated the high concentrations of Lead in Baghdad soils due to the emissions from Leaded fuel of cars, generators, and the industrials. These high concentrations in addition to their impact on human health may impact on the landscape and streambanks and may cause significant issues on soil erodibility. The erosion rate of cohesive soil was usually estimated using two alternative models, excess shear stress model which is depended on two major soil parameters: the critical shear stress, τc, and the erodibility coefficient, kd, and Wilson model which is depended on two mechanistic soil parameters: b0 and b1. A new miniature version of Jet Erosion Test (“mini” JET) was performed to derive both model parameters. The objective of this study was to investigate the influence of Lead pollution on cohesive soil erodibility using “mini” JET under controlled laboratory setups to predict soil erodibility. In order to observe the Lead contamination on soil erodibility, soil samples were mixed with different quantities of Lead concertation and the samples were packed at ASTM standard mold on two different bulk densities. Results show that the Lead pollution increased soil erodibility when the concentration of Lead increased. An inverse relationship between excess shear stress parameters kd and τc was observed as well as between Wilson model parameters b0 and b1. The Wilson model parameters were closely resembled the empirical excess shear stress parameters with benefit that Wilson model parameters are mechanistic parameters.

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Variations in Soil Erosion Resistance of Gully Head Along a 25-Year Revegetation Age on the Loess Plateau

Water ◽

10.3390/w12123301 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3301

Author(s):

Zhuoxin Chen ◽

Mingming Guo ◽

Wenlong Wang

Keyword(s):

Shear Stress ◽

Soil Erosion ◽

Erosion Resistance ◽

Stable State ◽

Critical Shear Stress ◽

Soil Erodibility ◽

Undisturbed Soil ◽

Concentrated Flow ◽

Detachment Rate ◽

Gully Head

The effects of vegetation restoration on soil erosion resistance of gully head, along a revegetation age gradient, remain poorly understood. Hence, we collected undisturbed soil samples from a slope farmland and four grasslands with different revegetation ages (3, 10, 18, 25 years) along gully heads. Then, these samples were used to obtain soil detachment rate of gully heads by the hydraulic flume experiment under five unit width flow discharges (2–6 m3 h). The results revealed that soil properties were significantly ameliorated and root density obviously increased in response to restoration age. Compared with farmland, soil detachment rate of revegetated gully heads decreased 35.5% to 66.5%, and the sensitivity of soil erosion of the gully heads to concentrated flow decreased with revegetation age. The soil detachment rate of gully heads was significantly related to the soil bulk density, soil disintegration rate, capillary porosity, saturated soil hydraulic conductivity, organic matter content and water stable aggregate. The roots of 0–0.5 and 0.5–1.0 mm had the highest benefit in reducing soil loss of gully head. After revegetation, soil erodibility of gully heads decreased 31.0% to 78.6%, and critical shear stress was improved by 1.2 to 4.0 times. The soil erodibility and critical shear stress would reach a stable state after an 18-years revegetation age. These results allow us to better evaluate soil vulnerability of gully heads to concentrated flow erosion and the efficiency of revegetation.

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Methods for Analyzing Submerged Jet Erosion Test Data to Model Scour of Cohesive Soils

Transactions of the ASABE ◽

10.13031/trans.14212 ◽

2021 ◽

Vol 64 (3) ◽

pp. 785-799

Author(s):

Tony L. Wahl

Keyword(s):

Shear Stress ◽

Erosion Rate ◽

Rate Coefficient ◽

Critical Shear Stress ◽

Cohesive Soils ◽

Simple Linear Regression ◽

Submerged Jet ◽

Rate Versus ◽

Erosion Test ◽

Stress Parameters

HighlightsFifty-two jet erosion tests performed on four cohesive soils were analyzed by nine different methods.Nonlinear methods performed well on some individual tests but fit inconsistently overall.Several alternate linear solution methods outperformed the widely used Blaisdell method.Simple linear regression of erosion rate versus applied shear stress provided the most consistent relationship between erosion rate and critical shear stress parameters.Abstract. The submerged jet erosion test (JET) is widely used in lab and field settings to quantify erodibility of cohesive soils and determine erosion rate coefficients and critical shear stress values. Test devices with different scales and configurations have been developed in recent years, along with several alternative methods for processing the collected data to determine parameters of linear and nonlinear soil erosion equations. To facilitate standardization, 52 JET experiments were conducted on four different cohesive soils compacted at optimum water content and 2% dry and wet of optimum. Each test was analyzed using nine different methods, four based on the linear excess stress equation (including the commonly used Blaisdell method) and five based on nonlinear erosion equations, including two using the recently popular Wilson model. Results were analyzed to determine the erosion equations and parameter-fitting methods that most effectively represent the observed erosion rates and are of greatest utility for soil erosion modeling and the ranking and classification of soils according to erodibility. Methods based on nonlinear erosion equations fit some data sets well, but they exhibited poor correlation between the erosion rate coefficient and the threshold shear stress parameter for initiating erosion, which is problematic for soil erodibility classification work. Linear methods that simultaneously optimized erosion equation parameters to best fit the total depth of scour or the elapsed time needed to reach specific depths of scour performed better than the Blaisdell method, which has been the informally accepted standard of practice since the late 1990s. However, they also exhibited weak correlation of the erosion rate and critical shear stress parameters. Simple linear regression of average scour rate versus average applied stress provided an effective method for representing the erosion rate versus applied stress curve and exhibited the strongest correlation of the erosion rate coefficient and critical shear stress parameters. Keywords: Cohesive soil, Critical shear stress, Erodibility, Erosion, Erosion laws, Erosion models, Jet erosion test, Shear strss, Soil moisture.

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Axial annular flow of a Giesekus fluid with wall slip above the critical shear stress

Journal of Non-Newtonian Fluid Mechanics ◽

10.1016/j.jnnfm.2015.05.004 ◽

2015 ◽

Vol 223 ◽

pp. 20-27 ◽

Cited By ~ 3

Author(s):

Mehdi Moayed Mohseni ◽

Fariborz Rashidi

Keyword(s):

Shear Stress ◽

Annular Flow ◽

Critical Shear Stress ◽

Wall Slip ◽

Giesekus Fluid

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Use of satellite and modeled soil moisture data for predicting event soil loss at plot scale

Hydrology and Earth System Sciences ◽

10.5194/hess-19-3845-2015 ◽

2015 ◽

Vol 19 (9) ◽

pp. 3845-3856 ◽

Cited By ~ 9

Author(s):

F. Todisco ◽

L. Brocca ◽

L. F. Termite ◽

W. Wagner

Keyword(s):

Soil Moisture ◽

Soil Loss ◽

Large Scale ◽

Central Italy ◽

Remote Sensing Data ◽

Loss Estimation ◽

Balance Model ◽

Estimation Accuracy ◽

Soil Losses

Abstract. The potential of coupling soil moisture and a Universal Soil Loss Equation-based (USLE-based) model for event soil loss estimation at plot scale is carefully investigated at the Masse area, in central Italy. The derived model, named Soil Moisture for Erosion (SM4E), is applied by considering the unavailability of in situ soil moisture measurements, by using the data predicted by a soil water balance model (SWBM) and derived from satellite sensors, i.e., the Advanced SCATterometer (ASCAT). The soil loss estimation accuracy is validated using in situ measurements in which event observations at plot scale are available for the period 2008–2013. The results showed that including soil moisture observations in the event rainfall–runoff erosivity factor of the USLE enhances the capability of the model to account for variations in event soil losses, the soil moisture being an effective alternative to the estimated runoff, in the prediction of the event soil loss at Masse. The agreement between observed and estimated soil losses (through SM4E) is fairly satisfactory with a determination coefficient (log-scale) equal to ~ 0.35 and a root mean square error (RMSE) of ~ 2.8 Mg ha−1. These results are particularly significant for the operational estimation of soil losses. Indeed, currently, soil moisture is a relatively simple measurement at the field scale and remote sensing data are also widely available on a global scale. Through satellite data, there is the potential of applying the SM4E model for large-scale monitoring and quantification of the soil erosion process.

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Field evidence of resuspension in a mine tailings pond

Canadian Geotechnical Journal ◽

10.1139/t01-005 ◽

2001 ◽

Vol 38 (4) ◽

pp. 796-808 ◽

Cited By ~ 17

Author(s):

Celestina Adu-Wusu ◽

Ernest K Yanful ◽

Mohammed H Mian

Keyword(s):

Shear Stress ◽

Mine Tailings ◽

Critical Shear Stress ◽

Field Measurements ◽

Shear Stresses ◽

Wind Speeds ◽

Tailings Pond ◽

Field Evidence ◽

Water Cover ◽

Solubility Of Oxygen

Flooding of tailings under shallow water covers is an effective method of decommissioning potentially acid generating mine tailings. The low diffusivity and solubility of oxygen in water are attractive features of this technology. However, wind-induced waves can resuspend flooded tailings and expose them to greater contact with dissolved oxygen, thereby increasing the potential for oxidation and acid generation. Field measurements of wind activity and waves under different water cover depths and associated resuspension for a mine tailings pond in Ontario are presented and discussed. The results show that wind speeds greater than 8 m/s above water covers that are shallower than 1 m create waves of height greater than 10 cm and bottom shear stresses greater than 0.2 Pa. Under these conditions the critical shear stress of the mine tailings was exceeded, resulting in erosion and subsequent resuspension.Key words: mine tailings, water cover, wind-induced waves, resuspension, wind speed, shear stress.

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