Estimation of Soil Material Transportation by Wind Based on in Situ Wind Tunnel Experiments

Abstract 25% and 40% of territory of Hungary is moderate to highly vulnerable to deflation. However, precise estimates about the soil loss and related losses of organic matter and nutrients due to wind erosion are missing in most cases. In order to determine magnitudes of nutrient masses removed at wind velocities that frequently occur in SE Hungary, in-situ experiments using a portable wind tunnel have been conducted on small test plots with an erosional length of 5.6 m and a width of 0.65 m. The wind tunnel experiments have been carried through on a Chernozem which is typical for this region. In order to compare the effects of soil coverage on the masses of blown soil sediment and adsorbed nutrients, two soil surface types have been tested under similar soil moisture und atmospheric conditions: (1) bare soil (dead fallow) and (2) bare soil surface interrupted by a row of maize plants directed downwind along the center line of the test plots. The results of our experiments clearly show that a constant wind velocity of 15 m s-1 (at a height of 0.3 m) lasting over a short time period of 10 minutes can already cause noticeable changes in the composition and size of soil aggregates at the top of the soil surface. Due to the grain size selectivity of the erosive forces the relative share of soil aggregates comprising diameters > 1 mm increased by 5-10% compared with the unaffected soil. Moreover it has shown that short time wind erosion events as simulated in this study can result in erosion rates between 100 and 120 g m-2, where the erosion rates measured for bare soils are only slightly, but not significantly higher than those of the loosely vegetated ones. Soil samples taken from sediment traps mounted in different heights close to the outlet of the wind tunnel point to an enrichment of organic matter (OM) of about 0.6 to 1 % by mass referred to the control samples. From these findings has been calculated that the relocation of organic matter within short term wind erosion events can amount to 4.5 to 5.0 g OM m-2. With the help of portable field wind tunnel experiments we can conclude that our valuable, high quality chernozems are struck by wind erosion mainly in drought periods.

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Wind tunnel experiments on the effects of tillage ridge features on wind erosion horizontal fluxes

Annales Geophysicae ◽

10.5194/angeo-23-3195-2005 ◽

2005 ◽

Vol 23 (10) ◽

pp. 3195-3206 ◽

Cited By ~ 9

Author(s):

M. Kardous ◽

G. Bergametti ◽

B. Marticorena

Keyword(s):

Wind Tunnel ◽

Wind Erosion ◽

Friction Velocity ◽

Soil Surface ◽

Trapping Efficiency ◽

Wind Tunnel Experiments ◽

Soil Factors ◽

Roughness Effect ◽

Data Set ◽

Horizontal Flux

Abstract. In addition to the well-known soil factors which control wind erosion on flat, unridged surfaces, two specific processes affect the susceptibility of tillage ridged surfaces to wind erosion: ridge-induced roughness and ridge- trapping efficiency. In order to parameterize horizontal soil fluxes produced by wind over tillage ridges, eight-ridge configurations composed of sandy soil and exhibiting ridge heights to ridge spacing (RH/RS) ratios ranging from 0.18 to 0.38 were experimented in a wind tunnel. These experiments are used to develop a parameterization of the horizontal fluxes over tillage ridged surfaces based only on the geometric characteristics of the ridges. Indeed, the key parameters controlling the horizontal flux, namely the friction velocity, threshold friction velocity and the adjustment coefficient, are derived through specific expressions, from ridge heights (RH) and ridge spacing (RS). This parameterization was evaluated by comparing the results of the simulations to an additional experimental data set and to the data set obtained by Hagen and Armbrust (1992). In both cases, predicted and measured values are found to be in a satisfying agreement. This parameterization was used to evaluate the efficiency of ridges in reducing wind erosion. The results show that ridged surfaces, when compared to a loose, unridged soil surface, lead to an important reduction in the horizontal fluxes (exceeding 60%). Moreover, the effect of ridges in trapping particles contributes for more than 90% in the flux reduction while the ridge roughness effect is weak and decreases when the wind velocity increases.

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Estimation of nutrient movement caused by wind erosion on chernozem soils in wind tunnel experiments

Agrokémia és Talajtan ◽

10.1556/agrokem.60.2011.1.7 ◽

2011 ◽

Vol 60 (1) ◽

pp. 87-102 ◽

Cited By ~ 4

Author(s):

Andrea Farsang ◽

József Szatmári ◽

Gábor Négyesi ◽

Máté Bartus ◽

Károly Barta

Keyword(s):

Wind Tunnel ◽

Wind Erosion ◽

Wind Tunnel Experiments ◽

Chernozem Soils

Összefoglalva megállapítható, hogy nagyobb szélsebesség hatására több talajanyag erodálódott, és ezzel együtt megnőtt az áthalmozott tápanyag mennyisége is. Minden vizsgált szélsebesség esetében a szélerózió következtében 3–7%-kal megnőtt az 1 mm és annál nagyobb szemcsék, illetve aggregátumok aránya a kiindulási talajanyag felső 0–1 cm-es rétegében. A finomabb szemcse-, illetve aggregátum-átmérők esetén a fújatást követően csökkenést tapasztaltunk. A leginkább a 315 μm és az annál kisebb szemcsék aránya csökkent, átlagosan 1–2%-kal. A minták kémiai és fizikai elemzéseiből megállapítható, hogy a láda utáni humuszosabb, aggregátumosabb szerkezetű minták N-tartalma nagyobb, mint az alapmintáé. A fogók mintáiban nem tapasztaltunk feldúsulást egy vizsgált elem esetében sem, a fogókban összegyűlt talajanyag kálium- és foszfortartalma is kisebb volt, mint az alapmintáé. Ennek oka, hogy az itt csapdázódott üledékben kisebb a tápanyag-megkötődés helyéül szolgáló leiszapolható rész aránya, mint a kiindulási talajanyagban. A vizsgálatainkból látszik, hogy a szélerózió hatására a lebegtetve, illetve ugráltatva áthalmozott talajszemcsékkel és aggregátumokkal szállított humusz 500–3500 kg/ha nagyságrendben mozoghat a vizsgált csernozjom területen akár egyetlen szélesemény hatására is. A kálium-áthalmozódás mértéke elérheti a 100 kg/ha értéket, a foszforé a 70 kg/ha-t, a nitrogénveszteség mértéke pedig akár 200–300 kg/ha is lehet egy szélesemény alkalmával. E tápanyagmennyiség nagy része több száz méter, de akár kilométeres távolságokra is távozhat a területről. Az általunk végzett szélcsatornás vizsgálatok eredményei becslésnek tekinthetők, hiszen vizsgálatunk során növénymaradvány-mentes, szitált és légszáraz talajanyaggal dolgoztunk. A szitálás eredményeként csupán a 2 mm-es és annál kisebb aggregátumok maradtak meg, ami azonban az intenzív művelés alá vont, porosodott, leromlott szerkezetű talajfelszín körülményeit jól közelíti. Ugyanakkor a természetben zajló széleróziós eseményeknek a szélcsatorna-kísérlet csak leegyszerűsített modellváltozata, hiszen az általunk szimulált szélesemények 15 percig tartottak, s nem tudtunk széllökéseket előállítani, melyek a széleróziós események alakulásában nagy jelentőségűek. Ennek tudatában kell a kapott eredményeket értékelni, mégis érdemes velük foglalkozni. A terepi mérésekkel szemben a szélcsatornában végzett vizsgálatoknak éppen az a legfontosabb előnye, hogy ellenőrzött, kontrollált körülmények között végezzük a méréseket, így rengeteg olyan szempontot meg tudunk vizsgálni, amit terepi mérésekkel lehetetlen lenne. Ilyen szempontok a pontos szélsebesség és szélirány hatása, az erodált felület nagysága és tulajdonságai. Kutatásunk következő lépése a szélcsatornás kísérletekkel vizsgált mintaterületeken terepi, mobil szélcsatornás vizsgálatok végzése, valamint terepi üledékcsapdák elhelyezésével a valós szélesemények által elszállított talaj mennyiségének és minőségének meghatározása. Célunk mind pontosabb képet alkotni a hazai jó minőségű csernozjom talajok szélerózió okozta tápanyagveszteségének mértékéről. A mezőgazdasági művelés alatt álló csernozjom területek feltalajában a tápanyag és szerves anyag szélerózió útján történő mozgási törvényszerűségeinek feltárása több szempontból is hasznos: segítséget jelent a területi tervezésben, a defláció szempontjából optimális területhasználat és művelési módok meghatározásában. Képet kapunk arról, hogy a legnagyobb gazdasági potenciállal rendelkező termőtalajunk milyen veszélyeknek van kitéve, s hogy a nem megfelelő időben, nem megfelelő nedvességviszonyok mellett történő talajművelés következtében kialakuló szerkezetromlás (porosodás) miatti deflációs károk milyen tápanyagveszteséggel járhatnak együtt.

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Spatio-temporal effects of vegetated windbreaks on wind erosion and microclimate as basis for model development

10.5194/egusphere-egu21-9182 ◽

2021 ◽

Author(s):

Thomas Weninger ◽

Simon Scheper ◽

Nathan King ◽

Karl Gartner ◽

Barbara Kitzler ◽

...

Keyword(s):

Soil Water ◽

Wind Erosion ◽

Arable Land ◽

Model Development ◽

Weather Conditions ◽

Bare Soil ◽

Sediment Traps ◽

Spatial And Temporal Variability ◽

Regional Modelling ◽

Erosion Rates

Wind erosion of arable soil is considered a risk factor for Austrian fields, but direct measurements of soil loss are not available until now. Despite this uncertainty, vegetated windbreaks have been established to minimize adverse wind impacts on arable land. The study addresses these questions: i) How relevant is wind erosion as a factor of soil degradation? ii) How important is the protective effect of vegetated windbreaks? iii) Are systematic patterns of spatial and temporal variability of wind erosion rates detectable in response to weather conditions?&#160;Two experimental fields adjacent to windbreaks were equipped with sediment traps, soil moisture sensors, and meteorological measurement equipment for microclimatic patterns. Sediment traps were arranged in high spatial resolution from next to the windbreak to a distance of ten times the windbreak height. Beginning in January 2020, the amount of trapped sediment was analyzed every three weeks. The highest wind erosion rates on bare soil were observed in June and July. For unprotected fields with bare soil, upscaled annual erosion rates were as high as 0.8 tons per hectare, and sediment trapped increased in a linear fashion with distance from the windbreak. Soil water content near the surface (5 cm depth) was three percent higher at a distance of two times the height of the windbreak than at a distance of six times the height. For the same respective distances from the windbreak, we observed 29 days of soil water contents below the wilting point compared with 60 days.The preliminary outcomes confirmed the expected effects of windbreaks on soil erosion and microclimate in agricultural fields. Prospective results from multiple vegetation periods will be used in an upscaling approach to gain informations for the whole basin. That is meant to be done by a combination with a soil wind erosion model which was so far used for regional modelling of wind erosion susceptibility.

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Physical Crust Formation on Sandy Soils and Their Potential to Reduce Dust Emissions from Croplands

Land ◽

10.3390/land9120503 ◽

2020 ◽

Vol 9 (12) ◽

pp. 503

Author(s):

Heleen Vos ◽

Wolfgang Fister ◽

Frank Eckardt ◽

Anthony Palmer ◽

Nikolaus Kuhn

Keyword(s):

Wind Erosion ◽

Sandy Soils ◽

Soil Surface ◽

Free State ◽

Cone Penetrometer ◽

Crust Formation ◽

Dust Emissions ◽

Dust Flux ◽

Dust Sources

The sandy croplands in the Free State have been identified as one of the main dust sources in South Africa. The aim of this study was to investigate the occurrence and strength of physical soil crusts on cropland soils in the Free State, to identify the rainfall required to form a stable crust, and to test their impact on dust emissions. Crust strength was measured using a fall cone penetrometer and a torvane, while laboratory rainfall simulations were used to form experimental crusts. Dust emissions were measured with a Portable In-Situ Wind Erosion Laboratory (PI-SWERL). The laboratory rainfall simulations showed that stable crusts could be formed by 15 mm of rainfall. The PI-SWERL experiments illustrated that the PM10 emission flux of such crusts is between 0.14% and 0.26% of that of a non-crusted Luvisol and Arenosol, respectively. The presence of abraders on the crust can increase the emissions up to 4% and 8% of the non-crusted dust flux. Overall, our study shows that crusts in the field are potentially strong enough to protect the soil surfaces against wind erosion during a phase of the cropping cycle when the soil surface is not protected by plants.

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Wind erosion of microplastics from soils: linking soil surface properties with microplastic flux

10.5194/egusphere-egu2020-17818 ◽

2020 ◽

Author(s):

Annie Ockelford ◽

Joanna Bulalrd ◽

Cheryl McKenna-Neuman ◽

Patrick O'Brien

Keyword(s):

Surface Roughness ◽

Wind Tunnel ◽

Wind Erosion ◽

Soil Surface ◽

Surface Characteristics ◽

Test Material ◽

Mineral Particle ◽

Test Bed ◽

Transport Pathway ◽

Soil Surface Roughness

Recent studies of soils in the Alps and Middle East indicate airborne transport of microplastics following wind erosion may be significant.&#160; Where microplastics have been entrained by wind they show substantial enrichment ratios compared to mineral particle erosion.&#160; Further, microplastic shape affects enrichment ratios with those for fibres greater than for microbeads which may reflect the lower density and asymmetric shape of microplastics compared to soil particles. This suggests that terrestrial to atmospheric transfer of microplastics could be a significant environmental transport pathway. However, currently we have very little understanding of how the properties, in particular the surface characteristics, of the sediment which they are being eroded from affects their entrainment potential.This paper reports wind tunnel studies run to explore the impacts of soil surface characteristics on microplastic flux by wind erosion.&#160; Experiments were performed in a boundary layer simulation wind tunnel with an open-loop suction design.&#160; The tunnel has a working section of 12.5m x 0.7m x 0.76m and is housed in an environmental chamber which, for this study, was held constant at 20 oC and 20% RH. In experiments two types of low density microplastic (microbeads and fibres) were mixed into a poorly-sorted soil containing 13% organics.&#160; The polyethylene microbeads had a size range of 212-250 microns and density of 1.2 g cm3 and the polyester fibres were 5000 microns long and 500-1000 microns in width with a density of 1.38 g cm3.&#160; Microplastics were mixed into the sediment in concentrations ranging from 40-1040 mg kg-1. For each experiment, test surfaces were prepared by filling a 1.0m x 0.35m x &#160;0.025m metal tray with the given mixture of test material which was lowered into the wind tunnel such that it was flush with the tunnel floor and levelled. The wind tunnel was then switched on and run with increasing wind speeds using 0.25 m s-1 increments until continuous saltation occurred.&#160; Soil surface roughness was scanned prior to and after each experiment using a high resolution laser scanner (0.5mm resolution over the entire test section). &#160;Transported soil and microplastic particles were captured in bulk using a 2 cm wide by 40 cm tall Guelph-Trent wedge trap that was positioned 2 m downwind of the test bed.&#160;Discussion concentrates on linking the changes in soil surface topography to the magnitude of microplastic flux where data shows that there is a correlation between the development of the soil surfaces and overall microplastic flux.&#160; Specifically, soil surface roughness is seen as a significant control on microplastic flux where it has a greater overall effect on microplastic fibre flux as compared to the microplastic beads.&#160; The outcome of this research is pertinent to developing understanding surrounding the likely controls and hence propensity of microplastics to be entrained from soil by wind erosion. &#160;

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EFFECT OF NONERODIBLE AGGREGATES AND WHEAT STUBBLE ON INITIATION OF SOIL DRIFTING

Canadian Journal of Soil Science ◽

10.4141/cjss70-004 ◽

1970 ◽

Vol 50 (1) ◽

pp. 31-34 ◽

Cited By ~ 11

Author(s):

FREDERICK BISAL ◽

W. S. FERGUSON

Keyword(s):

Wind Tunnel ◽

Wind Velocity ◽

Soil Aggregates ◽

Soil Surface ◽

Wheat Stubble ◽

The Relationship

The wind velocity required to initiate movement of soil with varying amounts of standing wheat stubble and varying proportions of erodible and nonerodible soil aggregates was determined in a wind tunnel. The relationship between these variables was calculated as logeI = 6.0438 + 0.0001774 S + 0.02332 C where I is the initiating velocity in cm/sec as measured at a height of 30.5 cm above the soil surface, S is the amount of standing wheat stubble (approximately 15 cm tall) in kg/ha, and C is the percentage of soil aggregates greater than 1 mm in diameter in a soil sample.The wind velocity required to initiate erosion is proposed as an index of erodibility of farm fields.

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Windbreak and airflow performance of different synthetic shrub designs based on wind tunnel experiments

PLoS ONE ◽

10.1371/journal.pone.0244213 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0244213

Author(s):

Xia Pan ◽

Zhenyi Wang ◽

Yong Gao ◽

Zhengcai Zhang ◽

Zhongjv Meng ◽

...

Keyword(s):

Wind Speed ◽

Wind Tunnel ◽

Wind Erosion ◽

Protective Effects ◽

Wind Tunnel Experiments ◽

Speed Reduction ◽

Environmental Threats ◽

Wind Speeds ◽

Airflow Field ◽

Reduction Effect

Wind erosion has gained increasing attention as one of the most serious global ecological and environmental threats. Windbreaks are effective at decreasing wind erosion by reducing wind speed to protect crops, livestock, and farmsteads, while providing wildlife habitats. Synthetic shrubs can act as novel windbreaks; however, there is limited knowledge on how their design affects wind speed. This study determined the protective effects (airflow field and sheltering efficiency) based on the design of synthetic shrubs in a wind tunnel. Broom-shaped synthetic shrubs weakened the wind speeds mainly at the middle and upper parts of the shrubs (5–14 cm), while for hemisphere-shaped shrubs this effect was greatest near their bases (below 4 cm) and least in the middle and upper parts (7–14 cm). Spindle-shaped synthetic shrubs provided the best reduction effect in wind range and strength. Moreover, the wind speed reduction ratio decreased with improved wind speeds and ranged from 26.25 cm (between the second and third rows) to 52.5 cm (after the third row). These results provide strong evidence that synthetic shrubs should be considered to decrease wind speed and prevent wind erosion.

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Computational Fluid Dynamics Simulation of Airflow through Standing Vegetation

Transactions of the ASABE ◽

10.13031/trans.13449 ◽

2019 ◽

Vol 62 (6) ◽

pp. 1713-1722

Author(s):

Howell B. Gonzales ◽

John Tatarko ◽

Mark E. Casada ◽

Ronaldo G. Maghirang ◽

Lawrence J. Hagen ◽

...

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Wind Tunnel ◽

Wind Erosion ◽

Canopy Structure ◽

Soil Surface ◽

Dynamics Simulation ◽

Vegetative Cover ◽

Drag Coefficients ◽

Standing Vegetation

Abstract. Maintaining vegetative cover on the soil surface is the most widely used method for control of soil loss by wind erosion. We numerically modeled airflow through artificial standing vegetation (i.e., simulated wheat plants) using computational fluid dynamics (CFD). A solver (simpleFoam within the OpenFOAM software architecture) was used to simulate airflow through various three-dimensional (3D) canopy structures in a wind tunnel, which were created using another open-source CAD geometry software (Salomé ver. 7.2). This study focused on two specific objectives: (1) model airflow through standing vegetation using CFD, and (2) compare the results of a previous wind tunnel study with various artificial vegetation configurations to the results of the CFD model. Wind speeds measured in the wind tunnel experiment differed slightly from the numerical simulation using CFD, especially near positions where simulated vegetation was present. Effective drag coefficients computed using wind profiles did not differ significantly (p <0.05) between the experimental and simulated results. Results of this study will provide information for research into other types of simulated stubble or sparse vegetation during wind erosion events.HighlightsMeasured airflow through a simulated canopy was successfully modeled using CFD software.Effective drag coefficients did not differ between the experimental and simulated results.Results of this study provide 3-D simulation data of wind flow through a plant canopy. Keywords: 3-D canopy structure, OpenFOAM, Wind erosion, Wind tunnel studies.

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Wind erosion controls on microplastics from soils: linking soil surface properties with microplastic flux

10.5194/egusphere-egu21-697 ◽

2021 ◽

Author(s):

Annie Ockelford ◽

Joanna Bullard ◽

Cheryl McKenna Neuman ◽

Patrick O'Brien

Keyword(s):

Surface Roughness ◽

Wind Tunnel ◽

Wind Erosion ◽

Soil Surface ◽

Surface Characteristics ◽

Test Material ◽

Mineral Particle ◽

Test Bed ◽

Transport Pathway ◽

Soil Surface Roughness

Recent studies of soils in the Alps and Middle East indicate airborne transport of microplastics following wind erosion may be significant.&#160; Where microplastics have been entrained by wind they show substantial enrichment ratios compared to mineral particle erosion.&#160; Further, microplastic shape affects enrichment ratios with those for fibres greater than for microbeads which may reflect the lower density and asymmetric shape of microplastics compared to soil particles. This suggests that terrestrial to atmospheric transfer of microplastics could be a significant environmental transport pathway. However, currently we have very little understanding of how the properties, in particular the surface characteristics, of the sediment which they are being eroded from affects their entrainment potential.This paper reports wind tunnel studies run to explore the impacts of soil surface characteristics on microplastic flux by wind erosion.&#160; Experiments were performed in a boundary layer simulation wind tunnel with an open-loop suction design.&#160; The tunnel has a working section of 12.5m x 0.7m x 0.76m and is housed in an environmental chamber which, for this study, was held constant at 20 oC and 20% RH. In experiments two types of low density microplastic (microbeads and fibres) were mixed into a poorly-sorted soil containing 13% organics.&#160; The polyethylene microbeads had a size range of 212-250 microns and density of 1.2 g cm3 and the polyester fibres were 5000 microns long and 500-1000 microns in width with a density of 1.38 g cm3.&#160; Microplastics were mixed into the sediment in concentrations ranging from 40-1040 mg kg-1. For each experiment, test surfaces were prepared by filling a 1.0m x 0.35m x&#160; 0.025m metal tray with the given mixture of test material which was lowered into the wind tunnel such that it was flush with the tunnel floor and levelled. The wind tunnel was then switched on and run with increasing wind speeds using 0.25 m s-1 increments until continuous saltation occurred.&#160; Soil surface roughness was scanned prior to and after each experiment using a high resolution laser scanner (0.5mm resolution over the entire test section).&#160; Transported soil and microplastic particles were captured in bulk using a 2 cm wide by 40 cm tall Guelph-Trent wedge trap that was positioned 2 m downwind of the test bed.&#160;Discussion concentrates on linking the changes in soil surface topography to the magnitude of microplastic flux where data shows that there is a correlation between the development of the soil surfaces and overall microplastic flux.&#160; Specifically, soil surface roughness is seen as a significant control on microplastic flux where it has a greater overall effect on microplastic fibre flux as compared to the microplastic beads.&#160; The outcome of this research is pertinent to developing understanding surrounding the likely controls and hence propensity of microplastics to be entrained from soil by wind erosion.&#160;

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