PDF | Soil is the most fundamental and basic natural resource for all life to survive. Water and wind erosion are two main agents that degrade. PDF | On 22, 2018, S G Telkar and others published Soil Erosion: Types and Their Mechanism. Soil erosion occurs when soil is removed through the action of wind and water at a greater rate than it is formed. SOIL. The soil covering the surface of the earth.
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Soil erosion is one form of soil degradation along with soil compaction, low The rate and magnitude of soil erosion by water is controlled by the following. Soil erosion is the detachment and movement of soil material. The process be natural or accelerated by human activity. Depending on the local landscape. SOIL EROSION. IPROMO COURSE 2015. Food security in mountain areas EXtraordinary Potential. Silvia Stanchi PhD – University of Torino (DISAFA.
Partially incorporated residues and residual roots are also important as these provide channels that allow surface water to move into the soil. The effectiveness of any protective cover also depends on how much protection is available at various periods during the year, relative to the amount of erosive rainfall that falls during these periods. Crops that provide a full protective cover for a major portion of the year e. Crop management systems that favour contour farming and strip-cropping techniques can further reduce the amount of erosion.
Tillage Practices The potential for soil erosion by water is affected by tillage operations, depending on the depth, direction and timing of plowing, the type of tillage equipment and the number of passes. Generally, the less the disturbance of vegetation or residue cover at or near the surface, the more effective the tillage practice in reducing water erosion.
Minimum till or no-till practices are effective in reducing soil erosion by water. Tillage and other practices performed up and down field slopes creates pathways for surface water runoff and can accelerate the soil erosion process. Cross-slope cultivation and contour farming techniques discourage the concentration of surface water runoff and limit soil movement. Forms of Water Erosion Sheet Erosion Sheet erosion is the movement of soil from raindrop splash and runoff water.
It typically occurs evenly over a uniform slope and goes unnoticed until most of the productive topsoil has been lost. Lighter-coloured soils on knolls, changes in soil horizon thickness and low crop yields on shoulder slopes and knolls are other indicators. Figure 3. The accumulation of soil and crop debris at the lower end of this field is an indicator of sheet erosion. Rill Erosion Rill erosion results when surface water runoff concentrates, forming small yet well-defined channels Figure 4.
These distinct channels where the soil has been washed away are called rills when they are small enough to not interfere with field machinery operations. In many cases, rills are filled in each year as part of tillage operations. Figure 4. The distinct path where the soil has been washed away by surface water runoff is an indicator of rill erosion. Gully Erosion Gully erosion is an advanced stage of rill erosion where surface channels are eroded to the point where they become a nuisance factor in normal tillage operations Figure 5.
There are farms in Ontario that are losing large quantities of topsoil and subsoil each year due to gully erosion. Surface water runoff, causing gully formation or the enlarging of existing gullies, is usually the result of improper outlet design for local surface and subsurface drainage systems. The soil instability of gully banks, usually associated with seepage of groundwater, leads to sloughing and slumping caving-in of bank slopes.
Such failures usually occur during spring months when the soil water conditions are most conducive to the problem. Gully formations are difficult to control if corrective measures are not designed and properly constructed. Control measures must consider the cause of the increased flow of water across the landscape and be capable of directing the runoff to a proper outlet.
Gully erosion results in significant amounts of land being taken out of production and creates hazardous conditions for the operators of farm machinery. Figure 5.
Gully erosion may develop in locations where rill erosion has not been managed. Bank Erosion Natural streams and constructed drainage channels act as outlets for surface water runoff and subsurface drainage systems. Bank erosion is the progressive undercutting, scouring and slumping of these drainageways Figure 6. Poor construction practices, inadequate maintenance, uncontrolled livestock access and cropping too close can all lead to bank erosion problems.
Figure 6. Bank erosion involves the undercutting and scouring of natural stream and drainage channel banks. Poorly constructed tile outlets also contribute to bank erosion. Some do not function properly because they have no rigid outlet pipe, have an inadequate splash pad or no splash pad at all, or have outlet pipes that have been damaged by erosion, machinery or bank cave-ins. The direct damages from bank erosion include loss of productive farmland, undermining of structures such as bridges, increased need to clean out and maintain drainage channels and washing out of lanes, roads and fence rows.
Effects of Water Erosion On-Site The implications of soil erosion by water extend beyond the removal of valuable topsoil. Crop emergence, growth and yield are directly affected by the loss of natural nutrients and applied fertilizers. Seeds and plants can be disturbed or completely removed by the erosion. Organic matter from the soil, residues and any applied manure, is relatively lightweight and can be readily transported off the field, particularly during spring thaw conditions.
Pesticides may also be carried off the site with the eroded soil. Soil quality, structure, stability and texture can be affected by the loss of soil. The breakdown of aggregates and the removal of smaller particles or entire layers of soil or organic matter can weaken the structure and even change the texture.
Textural changes can in turn affect the water-holding capacity of the soil, making it more susceptible to extreme conditions such as drought. Off-Site The off-site impacts of soil erosion by water are not always as apparent as the on-site effects. Eroded soil, deposited down slope, inhibits or delays the emergence of seeds, buries small seedlings and necessitates replanting in the affected areas.
Also, sediment can accumulate on down-slope properties and contribute to road damage. Sediment that reaches streams or watercourses can accelerate bank erosion, obstruct stream and drainage channels, fill in reservoirs, damage fish habitat and degrade downstream water quality. Pesticides and fertilizers, frequently transported along with the eroding soil, contaminate or pollute downstream water sources, wetlands and lakes.
Because of the potential seriousness of some of the off-site impacts, the control of "non-point" pollution from agricultural land is an important consideration. Keynote address.
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Factors considered throughout included identification of the potential sources of sediment from arable land; the key risk factors for soil erosion occurring during storm events; the infrastructure placed at risk by erosion and sedimentation; and the interventions that could be made to reduce erosion.
The axes are intended to capture the underlying factors controlling runoff: the soil management axis relates to the soil infiltration, storage, and the tillage regime, whereas the flow connectivity axis relates to runoff that has been mobilised and how efficiently it flows into and through the local drainage network. The risk associated with runoff generation is represented by a position plotted on the matrix.
A low risk corresponding to good soil management and low flow connectivity appears in the bottom left hand corner of the matrix and a high risk poor soil management and high flow connectivity in the top right hand corner Wilkinson et al. This allows the user to answer the questions according to the current or proposed management of a particular field or farm and generates a plot of the risk level on the 2D matrix. The position plotted on the matrix depends on the answers to all of the questions.
As has been discussed at length in previous work, interactive DSMs employ a simple scoring system to rank the level of risk, whereby an equal weighting is applied to each risk factor Hewett et al. Thus, what is plotted on the matrices is a relative risk, that is, the only way in which the results of monitoring and modelling are transposed onto the DSMs is through the understanding of the trajectory of increased or decreased risk Hewett et al. A set of initial questions were generated for use in the semistructured interviews.
The interviews involved collecting feedback on, reviewing, and refining a the questions; b the way in which they were plotted on the matrix; and c the form of the interactive tool itself. Figure 2 Open in figure viewer PowerPoint a Draft Erosion Risk Line used in semistructured interviews above ; b final version with check boxes showing current and potential risk levels below [Colour figure can be viewed at wileyonlinelibrary.
The proposed features and function of the tool were evaluated with reference to clarity of information, quick reference capability, and performance, whether in the field using a tablet or at a work station. Changes were made to tool design based on feedback collected at this event.
Although initial thoughts regarding tool design were that the CAVERTI tool would be similar to interactive DSMs produced in previous work, it was important to be receptive to alternatives.