MOVEMENT OF SOIL PARTICLES IN SALTATION

1962 ◽  
Vol 42 (1) ◽  
pp. 81-86 ◽  
Author(s):  
F. Bisal ◽  
K. F. Nielsen
Keyword(s):  
Wind Velocity ◽  
Constant Velocity ◽  
Soil Surface ◽  
Angle Of Incidence ◽  
Constant Ratio ◽  
Soil Particles ◽  
Impulsive Forces ◽  
Straight Lines

A study was made of the manner in which the movement of particles involved in saltation was initiated. The paths of flight of these particles while air borne were also studied.Evidence is presented to show initiation of movement can be caused by impulsive forces generated by differences in wind velocity, and by the distribution of particles, at the soil surface. Photographs of particles in saltation show that the paths of descent are nearly straight lines with an angle of incidence of about 6 ± 4 degrees. The data suggest that constant velocity in both the forward and downward directions is attained very quickly and that these velocities remain in essentially a constant ratio for most of the downward path.

scholarly journals An environmentally friendly soil improvement technology for sand and dust storms control

2019 ◽  
Vol 6 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Sareh Rajabi Agereh ◽  
Farshad Kiani ◽  
Kazem Khavazi ◽  
Hassan Rouhipour ◽  
Farhad Khormali
Keyword(s):  
Wind Velocity ◽  
Soil Loss ◽  
High Efficiency ◽  
Soil Stabilization ◽  
Soil Surface ◽  
Soil Samples ◽  
Dust Storms ◽  
Control Group ◽  
Soil Particles ◽  
And Control

Background: Dust storms occur when unchecked, strong, or turbulent winds combine with exposed loose and dried soil surfaces. Sand and dust storms have a significant impact on society, economy, and environment at local, regional, and global levels. The environmental and health hazards of such storms cannot be permanently reduced, however, by taking appropriate measures, its impact can be reduced. The present study aimed to investigate the effects of microbial precipitation of calcium carbonate (CaCO3) as a biocompatible agent on soil stabilization and control of dust storms using ureaseproducing bacteria (UPB) as a biological improvement technique, which were isolated, identified, sprayed on the soil surface. Methods: For this purpose, the erosion of bio-cemented soil samples was investigated experimentally in a wind tunnel under the condition of wind velocity of 0 to 98 km.h-1 in two soil types with sandy and silty texture in a completely randomized design with three replicates. Results: The investigation of the threshold wind velocity of soil particles showed that soil particles began to move at velocity of 8 and 10 km.h-1 in silty and sandy soils, respectively, but in all biological samples (MICP), particles did not move until the wind speed reached 97 km.h-1. It was also revealed that the weight loss of all MICP-treated samples at different wind velocities was significantly reduced compared to the control group. Differences in the amount of soil loss among bio-cemented samples and control treatments were even superior at higher velocities, so that at velocities more than 57 km.h-1, soil losses increased significantly in the control group, while in soils treated with bacteria, soil loss was very low (about 2.5 kg.m-2.h-1). Comparison of the bacteria used in this study also showed that Bacillus infantis and Paenibacillus sp3 had high efficiency in controlling dust storms. Conclusion: The formation of abrasion-resistant surface layers on soil samples treated by biocementation showed that cementation by biological methods could be an effective way to stabilize surface particles and control sand and dust storms.

scholarly journals Potential threat of southern Moravia soils by wind erosion

2004 ◽  
Vol 52 (2) ◽  
pp. 33-42 ◽  
Author(s):  
Jana Dufková
Keyword(s):  
Wind Velocity ◽  
Wind Erosion ◽  
Linear Trend ◽  
Soil Surface ◽  
Potential Threat ◽  
Soil Humidity ◽  
Average Wind ◽  
Humidity Index ◽  
Southern Moravia ◽  
Average Wind Velocity

Wind erosion is caused by meteorological factors such as wind, precipitation and evaporation that influence the soil humidity. Erosive-climatological factor expresses wind and humidity conditions of particular landscape. This is an index of the influence of average soil surface humidity and average wind velocity on average soil erodibility by wind. On the basis of average wind velocity and Konček’s humidity index, the values of the erosive-climatological factor for three chosen areas of Czech republic (Telč-Kostelní Myslová, Znojmo-Kuchařovice and Brno-Tuřany), where the pro-cesses of wind erosion could exist, were evaluated. Thus, the change of the factor’s value during the period of 1961 – 2000 was studied. The linear trend for the region of Brno and Znojmo (dry areas) shows increasing threat of soils by wind erosion, the contrary situation is at the humid area (Telč). The results prove the influence of soil humidity on the erosive-climatological factor and hereby the influence on wind erosion spreadout.

scholarly journals Experimental Setup for Splash Erosion Monitoring—Study of Silty Loam Splash Characteristics

2019 ◽  
Vol 12 (1) ◽  
pp. 157 ◽  
Author(s):  
David Zumr ◽  
Danilo Vítor Mützenberg ◽  
Martin Neumann ◽  
Jakub Jeřábek ◽  
Tomáš Laburda ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Soil Surface ◽  
Outer Diameter ◽  
Rainfall Simulator ◽  
Soil Particles ◽  
Splash Erosion ◽  
Laboratory Setup ◽  
Before And After ◽  
Silty Loam ◽  
Raindrop Splash

An experimental laboratory setup was developed and evaluated in order to investigate detachment of soil particles by raindrop splash impact. The soil under investigation was a silty loam Cambisol, which is typical for agricultural fields in Central Europe. The setup consisted of a rainfall simulator and soil samples packed into splash cups (a plastic cylinder with a surface area of 78.5 cm2) positioned in the center of sediment collectors with an outer diameter of 45 cm. A laboratory rainfall simulator was used to simulate rainfall with a prescribed intensity and kinetic energy. Photographs of the soil’s surface before and after the experiments were taken to create digital models of relief and to calculate changes in surface roughness and the rate of soil compaction. The corresponding amount of splashed soil ranged between 10 and 1500 g m−2 h−1. We observed a linear relationship between the rainfall kinetic energy and the amount of the detached soil particles. The threshold kinetic energy necessary to initiate the detachment process was 354 J m−2 h−1. No significant relationship between rainfall kinetic energy and splashed sediment particle-size distribution was observed. The splash erosion process exhibited high variability within each repetition, suggesting a sensitivity of the process to the actual soil surface microtopography.

A Thin Aerofoil of Small Camber in a Non-Uniform Flow

1967 ◽  
Vol 71 (675) ◽  
pp. 214-216
Author(s):  
L. N. Nigam
Keyword(s):  
Pressure Distribution ◽  
Stream Function ◽  
Constant Velocity ◽  
Direct Problem ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Angle Of Incidence ◽  
Pitching Moment ◽  
Image Position ◽  
General Profile

The direct problem of aerodynamics (profile of the aerofoil is given—calculate the aerodynamic characteristics) has been studied for thin aerofoils with small camber. Given the undisturbed stream functionV, ω, α being the constant velocity, vorticity and angle of incidence respectively, the pressure distribution, lift coefficient and pitching moment have been calculated for a general profile.

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

1970 ◽  
Vol 50 (1) ◽  
pp. 31-34 ◽  
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.

scholarly journals Determination of the installation parameters for additional attachments on the plowing unit for soil tillage

2021 ◽  
Author(s):  
V. Chebotarev ◽  
◽  
I. Kruk ◽  
F. Nazarov ◽  
Y. Chigariev ◽  
...  
Keyword(s):  
Power Consumption ◽  
Experimental Studies ◽  
Soil Surface ◽  
Soil Tillage ◽  
Kinematic Parameters ◽  
Technological Parameters ◽  
Soil Particles ◽  
Soil Movement ◽  
Working Surface

Summary. This article is dedicated to the subject of designing additional tools for use with reversible ploughs that cuts and loosens topsoil. The aim is to reduce power consumption spent for soil tillage by using reversible ploughs with roller cultivators. Methods. Theoretical and experimental studies of the topsoil movement on the plough’s wing, the mouldboard and beyond. Results. Analysis of the movement of soil particles falling from the top edge of the plough’s moulboard has allowed to obtain analytical dependence for determining the size range of soil particles based on the geometry of the working surface of the plough’s body (distance from the soil surface to the top edge of the mouldboard, the angles of the edge of the mouldboard) and the kinematic parameters of the soil (speed of the plough and roller cultivator, soil particles speed on the edge of mouldboard, soil particles descent time). A research, on the movement of the soil particles, on the mouldboard surface of the plough's body is presented. The section through the mouldboard perpendicular to the wing of the plough is described by the equation of the "inverted" cycloid and based on it the dependences have been obtained to determine the kinematic parameters of the movement of the soil particles on the surface of the plough’s body, depending on the mouldboard type and properties of the soil. Results obtained in this article allow to design the roller cultivators for reversible ploughs with determined parameters of installation, in which the power consumption costs of the plowing process will be minimal. Conclusions. Obtained analytical dependences, that determine kinematic and technological parameters of the soil movement on the working surface of the plow, the section through the orthogonal wing that has the form of an "inverted"cycloid, the variable design and technological parameters of the plough and the conditions of its operation, allowing to justify the installation parameters of the roller cultivator relative to the plough, taking into account the proposed correction ratio, which depends on the mechanical properties of the soil and its structure.

scholarly journals Assessment of the Detached Soil Particles and Water Discharge from a Bare Soil Surface under the Simulated Rainfall Conditions

2014 ◽  
Vol 7 (11) ◽  
pp. 2217-2224 ◽  
Author(s):  
Syed Muzzamil Hussain Shah ◽  
Khamaruzaman Wan Yusof ◽  
Zahiraniza Mustaffa ◽  
Ahmad Mustafa Hashim
Keyword(s):  
Water Discharge ◽  
Soil Surface ◽  
Bare Soil ◽  
Simulated Rainfall ◽  
Soil Particles

A Simple Nomogram for the Ratios of Octahedral to Maximum Shearing Stresses and Its Physical Interpretation

1954 ◽  
Vol 21 (3) ◽  
pp. 291-293
Author(s):  
G. A. Zizicas
Keyword(s):  
Physical Interpretation ◽  
Recent Observation ◽  
Stress Distributions ◽  
Shearing Stress ◽  
Constant Ratio ◽  
Principal Stresses ◽  
Absolute Value ◽  
The One ◽  
Straight Lines

Abstract A nomogram constructed exclusively by means of straight lines is presented, giving the ratio of the octahedral to the maximum shearing stresses for all possible stress distributions in terms of the nondimensional ratios of the two principal stresses to the one of maximum absolute value. The physical interpretation of the nomogram is discussed. It is shown that states of stress with constant ratio of octahedral to maximum shearing stress are represented by straight lines. To such lines are found to correspond fixed values of the deviatoric parameter μ = 2 S 2 - S 1 - S 3 S 1 - S 3 in agreement with a recent observation by Novozhilov. The values of μ are given directly by the nomogram.

Movement of Water Across Soils (Erosion)

1999 ◽  
Author(s):  
Robert F. Keefer
Keyword(s):  
Land Surface ◽  
Grand Canyon ◽  
Soil Surface ◽  
Bare Soil ◽  
Surface Flow ◽  
Running Water ◽  
Soil Particles ◽  
The Moment ◽  
New Location ◽  
Sheet Erosion

Erosion is the physical wearing away of the land surface by running water, wind, or ice. Soil or rock is initially detached by falling water, running water, wind, ice or freezing conditions, or gravity. Movement of the rock or soil may follow. Erosion is the combination of detachment and movement of soil or rock. Water erosion can be subdivided into either natural or man-made. Natural or geologic erosion does not require the presence of man. This process has been going on from the moment that land masses were uplifted. An example of geologic erosion is the Grand Canyon in Arizona. Man-made erosion is also called “accelerated erosion” as it is more rapid than natural erosion. Changes that man or animals have made to the soil by cultivation, construction, or any movement of earth often result in loss of soil by erosion. Accelerated erosion involves raindrop erosion, sheet erosion, surface flow, and landscapes. For raindrop erosion to occur, there must be detachment of soil particles followed by either transportation or compaction. Sheet erosion is the slow wearing away of the surface of soil. Surface flow occurs when sufficient water collects to run downhill, resulting in small soil cuts (rills) that often develop into large ruts (gullies). Landslides or slips occur when large chunks of soil move as a unit downhill, often resulting in drops of several feet or more. As rain falls, the drops strike the soil surface moving the soil particles with energy being expended in three kinds of ways: (a) detachment— soil particles are broken into smaller pieces, (b) transportation— small soil grains are moved to a new location as they splash into the air; movement can be downward, to sides, or up eventually acting as a smoothing agent, or (c) compaction—raindrops compact soil surface on bare soil forming a crust, resulting in running the soil particles together (puddling) so that air and water can no longer enter the soil. This causes loss of infiltration and results in runoff.

Efficient and environmentally friendly technologies of stumps removal on fellings

10.12737/2195 ◽  
2014 ◽  
Vol 3 (4) ◽  
pp. 146-151
Author(s):  
Поздняков ◽  
Evgeniy Pozdnyakov
Keyword(s):  
Soil Layer ◽  
Environmentally Friendly ◽  
Soil Surface ◽  
Soil Particles ◽  
Soil Application ◽  
Working Bodies

Shredding of stumps below the soil surface is constrained by intense abrasion of the cutting elements as a result of their interaction with the soil particles. Therefore, to solve this problem is to remove the stump from the upper soil layer. To perform this operation as a working bodies rip-strip off elements are encouraged to use in the form of pieces of rope that will not only prepare the ground around the stump, but also clear it from adhering soil. Application of this technology will reduce the abrasion and increase grinding period of cutting elements of machines for grinding stumps, thereby increasing their productivity.

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