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

Water ◽  
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.

Comparative study of soil erodibility and critical shear stress between loess and purple soils

2018 ◽  
Vol 558 ◽  
pp. 625-631 ◽  
Author(s):  
Hang Xing ◽  
Yu-han Huang ◽  
Xiao-yan Chen ◽  
Bang-lin Luo ◽  
Hong-xing Mi
Keyword(s):  
Shear Stress ◽  
Comparative Study ◽  
Critical Shear Stress ◽  
Soil Erodibility

Measuring soil erosion resistance on coastal dikes linking hyperspectral UAV-data, plant traits and soil information

2021 ◽  
Author(s):  
Jan-Michael Schönebeck ◽  
Maike Paul ◽  
Oliver Lojek ◽  
Boris Schröder ◽  
Jan Visscher ◽  
...  
Keyword(s):  
Shear Stress ◽  
Nutrient Availability ◽  
Root Architecture ◽  
Erosion Resistance ◽  
Critical Shear Stress ◽  
Economic Losses ◽  
Coastal Protection ◽  
Soil Parameters ◽  
Grazing Livestock ◽  
Sea Dike

<p>The integrity of a sea dike, especially its surface soil and biological revetment, is indispensable for coastal protection, as a dike breach would result in damages and economic losses. Estimates of the condition of a sea dike are typically established by on-site inspections and expert judgement at regular intervals. These status assessments of the protection level of the sea dike evaluate grass coverage and animal burrows, since structural inconsistencies deter the overall safety levels on coastal protection. In laboratory settings, erosion resistance of a sea dike is often determined by means of assessing critical shear stress induced by wave-run up and overtopping. Whereby the grain size distribution and soil aggregate formation on the one hand and the root penetration of the sample on the other are significant factors influencing critical shear stress and therefore erosion resistance. <br>Drone-/UAV-based remote sensing can be used to easily determine the degree of coverage of the dike revetment via green value detection. Thermal spectroscopy is also already used in agriculture to detect the state of health of plants at an early stage, for example due to a shortage of water. In addition, plants can be classified using hyperspectral imaging data. <br>We aim to derive transfer functions correlating ground truthing data, drawn from coastal real world- and a full scale laboratory dike, with plant species, its characteristic taxonomic traits and assessed top soil parameters. This approach bears the advantage of yielding an erosion-resistance estimate of the dike cover based on the plant classification using UAV-derived hyperspectral information. Furthermore, taxonomic species are sought to be paired with their respective, site specific, root architecture. Soil parameters such as nutrient availability and humidity will be observed and integrated into the approach, as they bear an impact on subterranean vegetation growth in that plants with lower nutrient availability develop a higher root network (high root length density [cm/cm³]). Finally, grazing livestock on the dike impacts the root system and soil structure as well and both aspects will be investigated comparing mowed against grazed areas as preliminary results show a dike cover void of grazing livestock exhibits a higher root shoot ratio than one with grazing. We hypothesize that classifying plants based on optical, hyperspectral UAV-derived data and the knowledge about the composition of the subsoil, the correlation of plant-specific root architecture and root growth with nutrient availability and agricultural maintenance could provide valuable information about erosion resistance of the dike cover to support dike inspection on an objective basis.</p>

scholarly journals Site-Specific Erodibility in Claypan Soils: Dependence on Subsoil Characteristics

2017 ◽  
Vol 33 (5) ◽  
pp. 705-718 ◽  
Author(s):  
Stacey E. Tucker-Kulesza ◽  
Gretchen F. Sassenrath ◽  
Tri Tran ◽  
Weston Koehn ◽  
Lauren Erickson
Keyword(s):  
Electrical Conductivity ◽  
Shear Stress ◽  
Soil Erosion ◽  
Soil Profile ◽  
Crop Production ◽  
Electrical Resistivity Tomography ◽  
Critical Shear Stress ◽  
Productive Capacity ◽  
Clay Layer ◽  
Resistivity Tomography

Abstract. Soil erosion is a primary factor limiting the productive capacity of many crop production fields and contributing to sediment and nutrient impairments of water bodies. Loss of topsoil is especially critical for areas of limited topsoil depth, such as the claypan area of the central United States. More than a century of conventional agricultural practices have eroded the topsoil and, in places, exposed the unproductive clay layer. This clay layer is impervious, limiting water infiltration and root penetration, and severely restricting agricultural productivity. Previous studies have documented changes in topsoil thickness using apparent electrical conductivity (ECa). However, that methodology is limited by its shallow depth of measurement within the soil profile, and as such cannot adequately explore factors within the soil profile that potentially contribute to topsoil erosion. In this study, we identified areas of limited topsoil depth using crop yields and ECa. Two areas within the production field varying in crop production and ECa were selected for detailed measurements using Electrical Resistivity Tomography. This methodology allowed delineation of soil stratigraphy to a depth of 5.3 m. The erodibility of undisturbed soil samples from the two areas were measured in an Erosion Function Apparatus to obtain the critical shear stress, or the applied stress at which soil begins to erode. Based on resistivity measurement, the highly productive region of the field had a thick (1.0-2.0 m) soil layer of saturated clayey sand soil over a uniform sandy material, with minimal clay layer. This soil had a critical shear stress of 12 Pa. The extent of historical erosion was evident in the poorly-producing area, as only a thin band of topsoil material remained over a thicker clay layer. The unproductive area with exposed clay layer had a critical shear stress of 128 Pa, indicating it was more resistant to erosion than the highly productive region. The clay layer was found to extend to 1.3-1.5 m in depth in the soil profile in the poorly producing area. Below this layer was a layer with similar resistivity to the high-producing region. The data reveal the extent of historical erosion within the crop production field and highlight significant variability in measured soil properties within a field of identical production practices. While spatial variations in topsoil have long been considered in developing management practices to improve soil health and productive capacity, our results indicate the importance of identifying variability of subsoil characteristics to address long-term impacts on soil erosion and productivity. Keywords: Soil erosion, Soil electrical conductivity, Claypan soil, Productive capacity, Electrical resistivity tomography.

scholarly journals Spatial Variability Modeling of Soil Erodibility Index in Relation to Some Soil Properties at Field Scale

2016 ◽  
Vol 6 (2) ◽  
pp. 16 ◽  
Author(s):  
C. Gyamfi ◽  
J. M. Ndambuki ◽  
R.W. Salim
Keyword(s):  
Organic Matter ◽  
Soil Erosion ◽  
Soil Properties ◽  
Bulk Density ◽  
Particle Density ◽  
Significant Variable ◽  
Soil Erodibility ◽  
Field Scale ◽  
Undisturbed Soil ◽  
Variability Modeling

<p class="1Body">Soil erosion is a major land degradation issue affecting various facets of human lives. To curtail soil erosion occurrence requires understanding of soil properties and how they influence soil erosion. To this end, the soil erodibility index which gives an indication of the susceptibility of soils to erosion was examined. In particular, we aimed to determine soil erodibility index at field scale and establish relationships that exist between selected soil properties and soil erodibility index. It was hypothesized that for soil erodibility index to vary spatially, then the existing soil properties should have varying spatial structure. Hundred disturbed and 100 undisturbed soil samples were collected from a 7.3 ha gridded area. The samples were analyzed for particle size distribution, bulk density, particle density, organic matter content and porosity. All soil analyses were conducted following standard procedures. Data were analyzed statistically and geostatistically on the basis of semivariograms. Sandy clay loam was the dominant soil texture in the studied field. Results indicate significant negative relationship between<strong> </strong>sand content, bulk density, particle density and organic matter with soil erodibility index. Silt correlated significantly with a positive relation with soil erodibility. Estimated erodibility for the sampled field ranged from 0.019 t.ha.hr/ha.MJ.mmto 0.055 t.ha.hr/ha.MJ.mm. The order of dominance of erodibility ranges were 0.038-0.042 t.ha.hr/ha.MJ.mm&gt; 0. 036-0.08 t.ha.hr/ha.MJ.mm&gt; 0.032-0.036 t.ha.hr/ha.MJ.mm&gt; 0.019-0.032 t.ha.hr/ha.MJ.mm&gt; 0.042-0.055 t.ha.hr/ha.MJ.mm. Regression analysis revealed silt to be the most significant variable that influences soil erodibility. The best regression of soil properties on soil erodibility index gave an R<sup>2 </sup>of 0.90. A comparison of the regression equation with other studies indicated good performance of the equation developed.</p>

Pressure conditions in the hole erosion test

2015 ◽  
Vol 52 (1) ◽  
pp. 114-119 ◽  
Author(s):  
Jaromír Říha ◽  
Jan Jandora
Keyword(s):  
Shear Stress ◽  
Soil Erosion ◽  
Numerical Study ◽  
Critical Shear Stress ◽  
Technical Note ◽  
Hydraulic Gradient ◽  
Hydraulic Gradients ◽  
Erosion Test ◽  
The Difference

The hole erosion test (HET) is used in the study of soil erosion in the case of what is known as “piping” when concentrated leaks occur. The HET enables the determination of soil erosion characteristics such as the critical shear stress along the pre-formed hole (pipe) and the coefficient of soil erosion. Normally, in the HET, the hydraulic gradient is determined from the difference between the piezometric heads measured at the inflow and outflow chambers (upstream and downstream of the soil specimen). Hydraulic analysis shows that such measurements ignore losses at the entrance and exit of the hole, causing the overestimation of the hydraulic gradient along the length of the hole, and thus the calculated shear stress. In this technical note, the results of preliminary analysis using the Bernoulli principle and of numerical study of the pressure conditions in the HET apparatus are shown. The turbulent flow in the HET apparatus was calculated using ANSYS commercial CFD (computational fluid dynamics) software. The analysis was performed for various hole entrance shapes. The conclusion of this note details the differences between traditionally determined hydraulic gradients and those numerically derived along the length of a hole.

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

2016 ◽  
Vol 20 (7) ◽  
pp. 3005-3012 ◽  
Author(s):  
Aliakbar Nazari Samani ◽  
Qiuwen Chen ◽  
Shahram Khalighi ◽  
Robert James Wasson ◽  
Mohammad Reza Rahdari
Keyword(s):  
Land Use ◽  
Shear Stress ◽  
Soil Erosion ◽  
Critical Shear Stress ◽  
Gully Erosion ◽  
Threshold Condition ◽  
Stream Power ◽  
Threshold Phenomenon ◽  
Erosion Models ◽  
Dry Farming

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 (τcr). The threshold unit stream power value (ωu) 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 τcr 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 τcr. In addition, based on the findings of this research, the use of threshold values of τcr  =  35 dyne cm−2 and ωu  =  0.4 cm s−1 in physically based soil erosion models is susceptible to high uncertainty when assessing gully erosion.

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

2022 ◽  
Vol 218 ◽  
pp. 105292
Author(s):  
Sanghyun Lee ◽  
Maria L. Chu ◽  
Jorge A. Guzman ◽  
Dennis C. Flanagan
Keyword(s):  
Shear Stress ◽  
Soil Loss ◽  
Critical Shear Stress ◽  
Loss Estimation ◽  
Soil Erodibility ◽  
Stress Parameters
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