Erosion term. Dangerous geological processes - erosion. Fertility - a unique property of the soil

16.03.2020

The destructive effect of water, wind and anthropogenic factors on the soil and underlying rocks, the demolition of the most fertile top layer or erosion is called erosion. Erosion causes great harm.

As a result of its activity, the humus horizon is washed away, the reserves of energy and nutrients in the soil are depleted, and, consequently, the energy potential decreases and fertility decreases. Suffice it to say that every centimeter of soil washed away is a loss of about 167472 * 10 6 J of energy from 1 hectare of field. These factors lead to a violation of the stability of the ecosystem, and these changes can be profound and even irreversible.

Types of erosion. According to the rate of manifestation of erosion processes, normal, or geological, and accelerated, or anthropogenic, erosion are distinguished.

normal erosion flows everywhere under forest and grassy vegetation. It manifests itself to a very weak degree, the soil is completely restored during the year due to soil-forming processes.

accelerated erosion develops where the natural vegetation is destroyed and the territory is used without taking into account its natural features, as a result of which the process of soil erosion is not covered by the processes of its self-recovery. Distinguish between ancient and modern soil erosion. The ancient one is represented by a hydrographic network (hollow, hollow, beam, valley). Ancient erosion ceased its action. Modern erosion takes place against the background of the ancient one, it is caused by both natural factors and human economic activity.

The following types of soil erosion are most common: water planar (washout) and linear, or vertical (washout);

wind (deflation); irrigation; industrial (technogenic); abrasion (collapse of the banks of water bodies); pasture (destruction of the soil by livestock); mechanical (destruction of the soil by agricultural machinery).

Planar erosion - this is the washout of the upper soil horizons on the slopes when rain or melt water flows down them in a continuous stream or streams. According to the degree of erosion, soils are distinguished as weakly, medium and strongly washed away. Slightly eroded soils include soils in which the upper horizon A is washed away to half its thickness, medium eroded - horizon A is eroded by more than half, strongly eroded - horizon B is partially eroded. - by 70%.

Linear erosion caused by melt and rainwater flowing down a significant mass concentrated within the narrow limits of the slope area. As a result, the soil is washed away in depth, deep gullies and potholes are formed, which gradually develop into ravines. Depending on the soil and climatic conditions, the growth and formation of the ravine proceed at a rate of 1–3 to 8–25 m per year.

Particularly dangerous is planar erosion, which gives impetus to the development of ravines, primarily because its manifestation is hardly noticeable. If a layer of soil with a thickness of only 1 mm per year is washed away from an arable land with an area of 1 ha, i.e. about 10 tons, this goes unnoticed, although in many cases the natural renewal of the soil is much lower. Another example is even more illustrative. If a ravine 100 m long, 5 m wide and 2 m deep is formed on a field of 100 ha, then the loss of soil and subsoil is 600-800 m 3 . The loss from the washout of the most fertile upper layer 1 cm thick from the same area (100 ha) is equivalent to the loss of approximately 10,000 m 3 of soil. To more clearly imagine the magnitude of the damage, it should be borne in mind that the permissible level of erosion for thick chernozems is 3 t/ha, ordinary and southern - 2.5, dark chestnut soils - 2 t/ha. However, real soil losses often exceed the indicated limits of its natural recovery.

With the increase in plowing of lands, the fight against this phenomenon is becoming increasingly important. Therefore, constant attention should be paid to the universal protection of forests and all vegetation, especially in mountainous and hilly areas, and their correct exploitation.

wind erosion, or deflation, observed both on light and heavy carbonate soils at high wind speeds, low soil moisture and low relative air humidity. Therefore, it mainly occurs in the arid steppe regions of the country. The plowing of light soils, their loosening, is especially dangerous in spring, when they are deprived of a protective green cover, which makes them vulnerable to deflation. Wind erosion manifests itself in the form of daily or local deflation and in the form of dust or black storms.

Dust storms, like winter blizzards, blow the loose layer, lift light and small particles and carry them over a certain distance. The lightest soil particles rise high into the air and are carried away far beyond their location, while the heavier ones jump or roll over to the first obstacle. The greatest danger is represented by jumping soil particles. They, hitting the soil, destroy it, increase the blowing, and when they meet fragile crops or perennial grasses, they pinpoint and fall asleep them. In large open spaces, bouncing soil particles, like a chain physico-chemical reaction with the advancement of a hurricane, cause more and more destruction in the soil. Dust storms on their way partially or completely destroy crops over large areas, fill up roads, irrigation canals, various buildings, irrevocably demolish the top, most fertile soil layer. Dust storms, polluting the environment, water, air, adversely affect the health of humans, domestic and wild animals.

Wind erosion in connection with deforestation and plowing of new lands covers more and more areas up to the forest-steppe and even taiga (Ulyanovsk region, Kazan Trans-Volga region, Lena river basin).

Irrigation erosion often observed in areas of irrigated agriculture; in the area of its activity, permanent and temporary reclamation networks are put out of action. The main reasons for its erosion are the weak fixation of the bottom and slopes of the canals, the insufficient number of conjugating structures during their reinforcement, the increase in slopes, the weak infiltration capacity of the soil, subsidence of soils, leading to a violation of the normal profile of the canals, their clogging, increased water consumption in irrigation furrows or strips. During the operation of irrigation systems in some areas, up to 20-45% of water is lost for various reasons due to filtration and leakage, which also contributes to soil erosion. Irrigation erosion manifests itself even in conditions of small slopes with an increase in irrigation jet. Irrigation without taking into account irrigation norms and weather conditions of the growing season leads to the accumulation of salts in the arable layer of the soil, which sometimes not only reduces soil fertility, but also completely removes such areas from agricultural use.

industrial erosion arises as a result of the development of minerals, especially open-pit mining, the construction of residential and industrial buildings, the laying of highways, gas and oil pipelines.

With erosion called abrasion(collapse of the banks of rivers and other water bodies), the area of arable land and pastures is decreasing, water bodies are silting up.

In connection with the overload of pastures with livestock, significant areas are exposed to pasture (path) erosion. It manifests itself in violation of the norms of grazing, carrying it out without taking into account the number of livestock, the capacity of pastures and meadows, when driving livestock through the same areas, without watering the places of driving by sprinkling in hot weather.

Erosion is the enemy of fertility. It is estimated that every minute on the globe 44 hectares of land go out of agricultural circulation. Every day more than 3 thousand hectares are irretrievably lost from erosion, and in total more than 50 million hectares of fertile land have already been lost. From flushing, erosion and blowing of the soil, the yield of all agricultural crops is reduced by an average of 20-40%. However, the damage caused by erosion does not stop there. The formation of gullies, hollows and ravines on the soil surface makes it difficult to cultivate the land and reduces the productivity of tillage and harvesting equipment. Soil erosion, and consequently, the destruction of habitats for plants and animals in biogeocenoses leads to a violation of the existing biological balance in natural complexes.

However, it should be noted that accelerated erosion is not an inevitable process. The high level of agricultural technology ensures the timely implementation of comprehensive protection against erosion.

Factors of manifestation of erosion processes

relief. The alternation of flat plains and uplands as a result of glacier activity. Novogrudok -330m, Minsk - 350m, Grodno region. 200-250m

climate. 3 climatic zones (northern, central and southern)

Soil cover and soil-forming rocks(planar on loams, wind on peatlands) Northern and Central parts - water erosion, Southern - wind erosion

vegetation,

Soil erosion control.

Erosion occurs as a result of irrational economic activity, improper use of land, poor agricultural practices in some farms. Grazing of animals without observing the norm of grazing and loading of livestock along the slopes of gullies and ravines, plowing of soil and inter-row cultivation along slopes, ill-conceived road construction, etc. against the background of ancient erosion, they contribute to the emergence and rapid growth of its new foci.

Washout and erosion of lands lead to siltation of reservoirs, shallowing of rivers, and clogging of the irrigation network. Fisheries, transport, energy facilities also suffer losses. Damage in agriculture from drought, plant and animal diseases, etc. much less than from soil erosion.

The fight against this phenomenon is one of the leading links in the high culture of agriculture. For each natural zone, in accordance with its physical and geographical conditions (soil, climate, relief), farming systems have been developed. The success of erosion protection largely depends on the observance of the basic rules of agricultural technology applied in a particular area, and on the nature of land use.

In areas of wind erosion, soil-protective crop rotations with strip placement of crops and fallows, backstage, grassing of heavily eroded lands, buffer strips of perennial grasses, fertilization, snow retention, fixation and afforestation of sands and other lands unsuitable for agricultural use, regulation of livestock grazing, cultivation of field-protective forest belts, and

non-moldboard tillage with stubble remaining on its surface.

In zones of development of water erosion, tillage and sowing of agricultural crops should be carried out across the slope, contour and ridge plowing, deepening of the arable layer, slotting and other methods of processing that reduce the runoff of surface water should be used; soil-protective crop rotations, strip placement of agricultural crops, grassing of steep slopes, fertilization, cultivation of field-protective and anti-erosion forest belts, afforestation of ravines, gullies, sands, banks of rivers and reservoirs, construction of anti-erosion hydraulic structures (drops, ponds, terracing, embankment of the tops of ravines and etc.).

In mountainous areas, anti-mudflow protection facilities, terracing, afforestation and grassing of slopes, alluvial fans, regulation of livestock grazing, and conservation of mountain forests are needed.

All of these activities are usually divided into groups: organizational and economic, agrotechnical, forest reclamation and hydraulic engineering.

For the practical implementation of anti-erosion work, first of all, a number of organizational and economic measures are required. These include the proper organization of the territory. On collective farms and state farms, areas are allocated that are to varying degrees subject to water and wind erosion, soil erosion plans are drawn up, on which categories of land subject to water and wind erosion are applied, for the differentiated application of anti-erosion measures.

In the United States, in the fight against water erosion, soil cultivation along horizontal lines or contour farming is widely and successfully used, which made it possible to increase the yield of the leading crops - corn, cotton, potatoes, etc. her fertility. In this case, some deviation from the horizontals is allowed in case of their strong crimp.

The deepening of the arable layer contributes to the retention of precipitation and the transfer of surface runoff into subsurface runoff. As a result of this technique, surface runoff in our country has decreased by about 25%, which has reduced the destructive effect of melt and rainwater.

Vegetation plays a particularly important role in protecting the soil from both slope runoff and rainstorms.

The high density of vegetation also ensures even distribution of snow on the fields. The root system of plants determines the erosion resistance, soil structuring. Dead parts of plants, their litter also contribute to a decrease in runoff and, in addition, to an improvement in the vital activity of microflora and mesofauna, and an increase in the biological activity of the soil.

Perennial legume-cereal grass mixtures fix the soil most reliably. They improve the physical properties of the soil, and also enrich it with nitrogen, phosphorus, calcium. Nodule bacteria that develop on the roots of leguminous grasses increase the content of nitrogen in the soil by fixing it from the air. At the same time, the importance of annual crops in the fight against erosion cannot be denied, although they are less resistant to it and have less ability to restore the fertility of eroded lands.

All cultures according to their anti-erosion properties can be divided into three groups. The first group, which best protects the soil from erosion, includes perennial ladders, the second - annual crops, which are significantly inferior to them in this regard. Row crops have the weakest protective effect, and in certain cases, if they are located along the slope, they can contribute to increased runoff and, thereby, erosion.

It is generally accepted that, compared with soil flushing under perennial grasses, its flushing under grain crops is 4-5 times higher, and under tilled crops - 25 times higher. Of the annual crops, winter crops protect the soil relatively well, since in spring and autumn they form an erosion-resistant vegetation cover. However, tilled crops in the second half of summer and early autumn provide a high projective cover and at this time reliably protect the soil from erosion. On the slopes, it is effective to create buffer strips across the slope from the same crop, but with an increased dose of fertilizers and an increased seeding rate, control of snowmelt by strip packing, etc.

Anti-erosion methods also include other methods: non-moldboard tillage with the preservation of stubble, dike and furrowing of fallow, mole, slotting, mulching with straw at the rate of 1-2 t/ha. For each ton of straw, 10 kg of nitrogen should be applied. Soil mulching on slopes with substandard straw at a dose of 1-3 t/ha reduces erosion by 3-5 times. Mulch also reduces the depth of soil freezing, which means it contributes to early spring absorption of runoff, weakening runoff and increasing crop yields.

On eroded soils, the creation of a wind-resistant surface layer is important. For this, special stubble seeders are used, and strip placement of crops and herbs is used.

The use of anti-erosion tools ensures the preservation of stubble on the soil surface, helps to retain snow in the fields, improves soil structure and sharply reduces wind erosion. Blow-resistant soil has 60% of particles larger than 1 mm in the upper 5 cm layer and is retained even at a wind speed of 12.5 m/s at a height of 0.5 m.

On soils subject to deflation (blowing), soil-protective crop rotations with the sowing of buffer strips from perennial grasses have especially justified themselves. On sandy soils, the area under perennial grasses should be increased to 50%. On less deflated soils, it is advisable to occupy 30% of arable land with them.

The creation of wings from tall plants (sunflower, corn) improves snow distribution in the fields, reduces the eroding energy of individual water jets, i.e. reduces soil erosion in general.

On plowing, to reduce erosion processes, it is necessary to create snow banks across the slope.

It should also be pointed out that fertilizer application is more efficient on eroded lands, since as a result of the application of the entire complex of anti-erosion measures, the washout of the soil, and, consequently, of the nutrients introduced into it, is sharply reduced.

In the fight against water and irrigation erosion, slotting is effective, which helps to increase the water permeability of heavy soils. Another way is to use sprinklers with low and medium rain intensity (up to 0.3 mm/min). This makes it possible to increase the irrigation rate to 700-800m 3 of water per 1 ha without the formation of surface runoff, save water, avoid salinization and reduce soil fertility.

Forest reclamation is also an important part of the anti-erosion complex.

PROTECTION OF SOILS FROM SALINATION, ACIDIFICATION AND WAGSING

These processes contribute to a sharp disruption of the normal functioning of the soil-plant system.

Soil salinization - accumulation of soluble salts and exchangeable sodium in concentrations that are not acceptable for normal growth and development of plants. Among saline soils, saline soils with a high concentration of soluble salts are distinguished; solonetzic, containing more than 5-10% of exchangeable sodium; solonchaks and salt marshes. Even with low salinity, the yield of corn, for example, decreases by 40-50%, wheat - by 50-60%.

Every year, due to salinization, 200-300 thousand hectares of irrigated land are out of circulation on the globe. Salt lands need to be washed fresh water, but at the same time another problem arises - the discharge of saline wash waters, which form huge salt marshes-sors. Discharged waters are saturated with fertilizers, pesticides and defoliants, which are toxic to humans and animals.

One of the salinity factors is wind. It captures salty dust and transports it long distances deep into the continents. A similar phenomenon is observed in the Aral Sea region, where the wind increases the removal of salts and dust from the dried bottom of the sea and their transfer to the territory of the region.

Soil salinization is possible due to improper agricultural practices, saline layers turning to the surface, excessive load of livestock on pastures. Soil salinization can be caused by irrigation water itself if it contains high concentrations of soluble salts.

Cases of accumulation of easily soluble salts (up to 500 kg per 1 ha) under the influence of halophyte vegetation have been noted.

Most often, salinization occurs due to the enrichment of the soil with salts that are contained in groundwater. Simultaneously with an increase in their level, moisture rises through the capillaries to the rhizosphere zone, where salts accumulate as water evaporates in it. The drier the climate and the heavier the soil in terms of granulometric composition, the more pronounced this process, the more pronounced the toxicity of salts in relation to plants. The increased content of salts in the soil causes an increase in the osmotic pressure of the soil solution, which makes it difficult to supply plants with water, they are chronically starving, their growth is weakened. This primarily affects the root system, which loses turgor and dies. Sodium carbonate is especially dangerous for plants. If the soil of exchangeable sodium contains 10-15% of the absorption capacity, the state of the plants turns out to be oppressed, with its content in the range of 20-35%, the inhibition is very strong.

With increased irrigation rates, losses of irrigation water from canals, the level of groundwater also rises. The process when salt accumulation in the soil occurs as a result of a violation of the irrigation regime and water filtration in irrigation canals is called secondary salinity.

As preventive measure To combat secondary salinization, it is necessary to drain the territory using pottery, plastic and other pipes laid to a depth of 1.0-1.8 m with a distance between drains from 5 to 15 m. Irrigation with sprinkling machines with low and medium rainfall (up to 0.3 mm/min) is also safe in this respect. Intrasoil, drip, fine and impulse irrigation are promising. The common advantage of these methods is water saving. So, with subsoil irrigation, the irrigation rate can be reduced to 100-300 m 3 /ha. The water consumption for pulse irrigation is only 0.01 mm/min. Due to low irrigation rates, the likelihood of salinization and waterlogging decreases. An important advantage of new irrigation methods is the reduction of evaporation from the soil surface, and in case of finely dispersed irrigation, transpiration. With drip irrigation, water in the form of a drop is supplied directly to the roots. The use of these irrigation methods prevents irrigation erosion, so they can be used on slopes.

The creation of forest belts along the canals also ensures the constancy of the groundwater level, as the trees intercept and transpire the filtered water, acting as biological drainage. To remove salts from the soil, flushing with fresh water is used.

With an increase in soil acidity (pH below 7), its productivity also decreases: the concentration of mobile aluminum increases and, at the same time, the content of nutrients decreases. Acidification depends on the absorption capacity, granulometric composition, water permeability, biological activity of the soil and the content of humus in it. Physiologically acidic nitrogen fertilizers increase soil acidity. Therefore, liming and fertilization rich in calcium are recommended on such lands. Without the use of lime, the effectiveness of fertilizers is reduced.

Waterlogging of the soil, leading to swamping, is widespread in a number of areas of the Non-Chernozem zone, and is also observed in other areas near canals, reservoirs and unplugged artesian wells. On the globe, about 8% of the land is subject to swamping and flooding.

To drain wetlands, slotted drains are cut into the ground. On heavy lands, drains are created using mole plows. On the Far East complex drainage is used, which is a combination of tubular drains with a network of molehills. Of the other preventive measures, the optimal irrigation method and strict adherence to the crop irrigation regime are effective. Closed drainage has an advantage over an open drainage network, since in this case the usable area is not lost.

However, dehumidification should be carried out within reasonable limits. A decrease in the level of groundwater during the drainage of swamps by more than 1.5 m from the soil surface contributes to the rapid oxidation of peat and the removal of nutrients into drainage ditches. With a further decrease in their level, the root-inhabited horizon is separated from the capillary rim, which leads to the death of forests.

The development of new lands must be carried out taking into account the protection of nature. Sometimes there is still an opinion that swamps cause great harm, so it is necessary to drain them. However, it should be remembered that swamps perform an important water management function, feeding rivers and groundwater, cleaning polluted precipitation.

Reclamation of wetlands should be carried out taking into account the protection of natural resources from depletion and undesirable impacts on the nature of the Non-Chernozem Zone. In this regard, much attention should be paid to environmental control and a broad discussion of projects.

The rocks on the surface are gradually destroyed under the influence of erosion processes, or weathering. There are two main types of erosion - mechanical and chemical. Most rocks are destroyed as a result of the combined effect of these types of erosion. Fragments of crumbled rocks are carried away by the waters and continue to collapse under the influence of various factors. When moving, the fragments continue to be crushed by other rocks, while forming more and more new fragments. Further destruction of the fragments can turn them into sand and dust. Delamination is sometimes called peeling, as the rocks are stratified like onion skins.

Erosion also occurs after small fragments of stones have already accumulated as a result of weathering. Water, ice and wind carry rock fragments, which along the way beat and rub against other rocks, turning into sand and dust. In the end, they settle in a new place.

mechanical erosion

During the day, it heats the surface of the rocks, and the minerals expand. At night it falls, and the minerals shrink. Most rocks typically contain many types of minerals that expand and contract at different rates and intensities, resulting in cracking and surface failure. This is the basic scheme of mechanical erosion. If the rock contains minerals of the same type, then entire areas of the surface alternately expand and contract, causing the so-called delamination.

In cold regions, rocks that have already developed cracks and splits can be destroyed by the process of melting and freezing. Getting into such cracks, it freezes and expands them. The ice causes great stress and pressure in the rocks, enlarging and widening the cracks. When the temperature rises, the ice melts, and when the temperature drops, it freezes again. Over time, blocks of stone crumble into pieces.

Water that gets into the cracks freezes and gradually expands them. The process of melting and freezing breaks rocks into pieces. Fragments, accumulating, form rubble dumps, which slide down under their own weight.

Freezing effect

By freezing a piece of clay in the refrigerator, you can visually demonstrate the effect of melting and freezing. This will require two lumps of clay (one for comparison), polyethylene for wrapping and the presence of a refrigerator. You can use clay from your garden.

What you need:

1.Knead both lumps of clay to squeeze out the bubbles and make them more compact. Thoroughly knead each lump.

2. Wrap each wad in plastic wrap. One put in freezer refrigerator, and the other on the windowsill. Leave them overnight.

3. Remove the clay from the refrigerator in the morning and remove the lump from the windowsill. When the clay from the refrigerator thaws, compare it with the one that lay overnight on the windowsill. Cracks in the thawed clay testify to the effect of melting and freezing.

chemical erosion

Chemical erosion occurs when minerals are dissolved by chemicals found in acid rain, for example. Even ordinary rain absorbs gases from the air, resulting in the formation of a weak acid that actively affects the rocks. In rocks such as limestone, caustic rainwater enters the cracks, significantly increasing them. Chemicals contained in rainwater gradually corrode the rocks.

acid rain

Acid rain is caused by severe air pollution. When fossil fuels, such as coal and coal, are burned, gases containing sulfur and nitrogen are formed. These substances react with water droplets to form acids and turn ordinary rain into acid rain. that carry acid rain can travel great distances. Thermal power plants emit a lot of waste gases.

Acid rain destroys the protective film on the leaves of plants and penetrates into them through the roots. Acid rain, falling on the surface, is absorbed into the soil and enters rivers and lakes, killing all life. Acid rain markedly increases chemical erosion. In the rocks, it causes great damage to ancient buildings and statues.

Erosion as a result of vital activity of plants and animals

Plants and animals actively contribute to the destruction of rocks by mechanical and chemical erosion. Plant roots can penetrate the cracks and enlarge them further. Some lichens secrete a weak acid that corrodes the surface of rocks. Animals digging holes for themselves in softened rocks contribute to the penetration of water into them.

Rivers

Rivers carry a lot of debris in their waters, which gradually destroy their channels and banks. As soon as the flow of the river slows down, these debris are deposited on the bottom. Seas. Waves pick up small pebbles and sand, carrying them along the coast and causing intense erosion of the coastal strip. They also carry rocks and sand ashore. Ice. In cold regions, fragments of stones often freeze into ice. When the ice slides, these fragments rub against the rocks, causing their intense erosion.

Wind

The wind picks up small particles and, throwing them onto rocks, actively destroys them. Wind erosion is especially powerful in deserts.

erosion acceleration

Human activity contributes to the acceleration of erosion. For example, soil erosion by wind and water has become a serious problem in many areas. Large areas of forests have been cut down for fields and other household needs. Plant roots no longer hold the top layers of the soil. The winds blow away the soil, leaving a dusty void in its place.

Destruction and demolition of the upper most fertile soil horizons as a result of the action of water and wind.

Often, especially in foreign literature, erosion is understood as any destructive activity of geological forces, such as sea surf, glaciers, gravity; in this case, erosion is synonymous with denudation. However, there are also special terms for them: abrasion ( wave erosion), exaration ( glacial erosion), gravitational processes, solifluction, etc. The same term (deflation) is used in parallel with the concept wind erosion, but the latter is much more common.

According to the rate of development, erosion is divided into normal and accelerated. Normal occurs always in the presence of any pronounced runoff, proceeds more slowly than soil formation and does not lead to a noticeable change in the level and shape of the earth's surface. Accelerated soil formation is faster, leads to soil degradation and is accompanied by a noticeable change in relief.

For reasons allocated natural and anthropogenic erosion. It should be noted that anthropogenic erosion is not always accelerated, and vice versa.

wind erosion

This is the destructive action of the wind: waving sands, forests, plowed soils; occurrence of dust storms; grinding of rocks, stones, buildings and mechanisms with solid particles carried by the force of the wind. Wind erosion is divided into two types:

Daily

The beginning of a dust storm is associated with certain wind speeds, however, due to the fact that flying particles cause a chain reaction of detachment of new particles, it ends at speeds much lower.

The strongest storms took place in the USA in the 1930s (“Dusty Pot”) and in the USSR in the 1960s, after the development of virgin lands. Most often, dust storms are associated with irrational economic activity people, namely, massive plowing of land without carrying out soil protection measures.

There are also specific deflationary landforms, the so-called " blowing basins": negative forms, elongated in the direction of the prevailing winds.

water erosion

drip erosion

Destruction of the soil by impacts of raindrops. Structural elements (lumps) of the soil are destroyed under the action of the kinetic energy of raindrops and are scattered to the sides. On slopes, downward movement occurs over a greater distance. Falling, soil particles fall on a film of water, which contributes to their further movement. This type of water erosion is of particular importance in the humid tropics and subtropics.

planar erosion

Planar (surface) erosion is understood as a uniform washout of material from slopes, leading to their flattening. With some degree of abstraction, they imagine that this process is carried out by a continuous moving layer of water, but in reality it is produced by a network of small temporary water flows.

Surface erosion leads to the formation of eroded and alluvial soils and, on a larger scale, deluvial deposits.

Linear erosion

Unlike surface erosion, linear erosion occurs in small areas of the surface and leads to the dismemberment of the earth's surface and the formation of various erosion forms (gullies, ravines, gullies, valleys). This also includes river erosion produced by constant flows of water.

The eroded material is deposited usually in the form of alluvial fans and forms proluvial deposits.

Types of linear erosion

An example of combined side and deep erosion. Sukhona coast

Deep(bottom) - destruction of the bottom of the watercourse. Bottom erosion is directed from the mouth upstream and occurs before the bottom reaches the level of the erosion basis.
Lateral- destruction of the coast.

In each permanent and temporary watercourse (river, ravine), both forms of erosion can always be found, but in the early stages of development, the deep one prevails, and in the subsequent stages, the lateral one.

Mechanism of water erosion

The chemical impact of surface waters, which include river waters, is minimal. The main cause of erosion is the mechanical impact on the rocks of water and the debris carried by it, previously destroyed rocks. In the presence of debris in the water, erosion increases sharply. The greater the flow velocity, the larger the debris is transferred, and the more intense the erosion processes.

To assess the resistance of soil or soil to the action of a water flow, you can critical speeds:

Non-blurring speed - maximum speed flow, in which there is no separation and movement of particles.
Scouring speed - the minimum flow rate at which the incessant detachment of particles begins. (Mirtskhulava T. E. Erosion of channels and a technique for assessing their stability. - M .: Izd-vo, Kolos, 1967.)

For soils and polydisperse soils, the concept of non-erosion velocity has no physical meaning, since even at the lowest velocities, the smallest particles are removed. In a turbulent flow, the separation of particles occurs at maximum pulsation velocities, therefore, an increase in the amplitude of the flow velocity fluctuation causes a decrease in critical velocities for a given soil.

spreading erosion

Erosion processes are widespread on Earth everywhere. wind erosion prevails in arid climate conditions, water erosion- in a humid climate.

Notes

Mirtskhulava T. E. Fundamentals of physics and mechanics of channel erosion. L .: Publishing house Gidrometeoizdat, 1988.

Links

Erosion in the ABC of the Earth: How do natural arches form?

Wikimedia Foundation. 2010 .

See what "Erosion (geology)" is in other dictionaries:

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According to the rate of development, erosion is divided into normal and accelerated. Normal occurs always in the presence of any pronounced runoff, proceeds more slowly than soil formation and does not lead to noticeable changes in the level and shape of the earth's surface. Accelerated soil formation is faster, leads to soil degradation and is accompanied by a noticeable change in relief.

For reasons allocated natural and anthropogenic erosion. It should be noted that anthropogenic erosion is not always accelerated, and vice versa.

Wind erosion (deflation)

Daily

The strongest storms took place in the USA in the 1930s (“Dusty boiler”) and in the USSR in the 1960s, after the development of virgin lands. Most often, dust storms are associated with irrational human economic activity, namely, the massive plowing of land without carrying out soil protection measures.

There are also specific deflationary landforms, the so-called " blowing basins": negative forms, elongated in the direction of the prevailing winds.

water erosion

water erosion occurs under the influence of temporary flows of atmospheric water (rain showers, melt water, etc.).

drip erosion

planar erosion

Surface erosion leads to the formation of eroded and washed-out soils, and on a larger scale - deluvial deposits.

Linear erosion

The eroded material is usually deposited in the form of alluvial fans and forms proluvial deposits.

Types of linear erosion

Deep(bottom) - destruction (corrosion) of the bottom of the watercourse. Bottom erosion is directed from the mouth upstream and occurs until the bottom reaches the level of the erosion base.
Lateral- destruction of the coast.

Mechanism of water erosion

The chemical impact of surface waters, which include river waters, is minimal. The main cause of erosion is the mechanical impact on the rocks of water and the fragments carried by it, previously destroyed rocks. In the presence of debris in the water, erosion increases sharply. The greater the flow velocity, the larger the debris is transferred, and the more intense the erosion processes.

To assess the resistance of soil or soil to the action of a water flow, you can critical speeds:

Erosion of technogenic origin

Vegetation cover is a decisive factor in soil stabilization and protection of soils from all types of erosion. Trees and shrubs, herbage with a developed root system effectively reduce the speed of near-surface air flows during wind, absorb the energy of falling drops during rain and dissipate water flows on the surface.

Therefore, under man-made impacts associated with soil exposure, for example, earthworks during construction, quarrying, sludge storage, etc., there is a danger of a sharp increase in the volume of soil loss due to erosion. For example, when arranging an arable field on heavy loamy sandy soil with a slope of 10 °, the erosion rate increases by 50-250 times (compared to grass cover), and 7000-35000 times (compared to a forested area). In the absence of anti-erosion measures, soil loss can be 1-10 cm per year. Forms of water erosion (drip, surface and linear) differ in the impact of soil loss. On the test slope (sandy soil, slope 11°), soil losses were distributed in the ratio 1:20:950. With an increase in the percentage of silty particles, the tendency to erosion increases.

Soil erosion is a significant risk factor in the implementation of infrastructure, construction and agricultural projects, therefore, after carrying out soil work, it is recommended to immediately apply grass seeding (“greening”) to restore the damaged surface and strengthen the slopes. To ensure sufficient protection of the soil in the period between grass seeding and obtaining a stable vegetation cover, a protective coating is often applied along with sowing: manually - biomats, mechanically -

Definition of soil erosion

Erosion is the destruction of soil by wind and water, the movement of destruction products and their redeposition. Soil damage (erosion) by water manifests itself mainly on slopes from which water flows, rain or melt. Erosion is planar (when the soil is evenly washed away by water runoff, which does not have time to be absorbed), it is jet-like (shallow ravines are formed, which are eliminated by conventional processing), and there is still deep erosion (when it erodes the soil and rocks with strong water flows). Soil destruction by wind, otherwise called deflation, can develop on any type of terrain, even on plains. Deflation is everyday (when winds of low speed lift soil particles into the air and transfer them to other areas), the second type of wind erosion is periodic, that is, dust storms (when winds at high speed lift the entire top layer of soil into the air, it happens even with crops , and carries these masses over long distances).

Types of soil erosion

Depending on the degree of destruction, two types of soil erosion can be distinguished: normal erosion, that is, natural, and accelerated, that is, anthropogenic. The first type of erosion occurs slowly and does not affect the fertility of the soil. Accelerated erosion is closely related to the economic work of man, that is, the soil is not cultivated correctly, the vegetation cover is disturbed during grazing, and so on. With the rapid development of erosion, soil fertility decreases, crops are damaged, agricultural land becomes inconvenient due to ravines, this makes it very difficult to cultivate fields, rivers and reservoirs are flooded. Due to soil erosion, roads, power lines, communications and much more are destroyed. It causes great damage to agriculture.

Soil erosion prevention

For many years, the fight against soil erosion has been one of the important state tasks in the development of Agriculture. To solve it, various zonal complexes are being developed that complement each other, for example, organizational and economic, agrotechnical, hydraulic engineering, forest reclamation anti-erosion measures.

A little about each event. Agrotechnical measures include deep cultivation of plots across slopes, sowing, plowing, which alternates every two or three years with ordinary plowing, slotting of slopes, spring loosening of the field in strips, grassing of slopes. All this contributes to the regulation of rain and melt water runoff, and, accordingly, significantly reduces soil runoff. In areas where wind erosion is common, instead of plowing, flat-cut tillage is used by cultivators, that is, flat-cutters. This reduces atomization and helps build up more moisture.

In every area that is subject to soil erosion, soil-protective crop rotations play a huge role, and in addition, sowing crops of high-stemmed plants.

In forest reclamation measures, protective forest plantings have a great effect. Forest belts are field-protective, ravine and ravine.

In hydrotechnical measures, terracing is used on very steep slopes. In such places, shafts are built to retain water, and ditches, on the contrary, to remove excess water, fast drains in the channels of hollows and ravines.

Soil protection from erosion

Erosion is considered the biggest socio-economic disaster. It is proposed to follow the following provisions: firstly, it is easier to prevent erosion than to fight it later, eliminating its consequences; in environment not find soils that are completely resistant to erosion; due to erosion, changes in the main functions of the soil occur; this process is very complex, the measures taken against it must be comprehensive.

What affects the erosion process?

Any erosion can occur due to such factors:

changes in climatic conditions;
terrain features;
natural disasters;
anthropogenic activity.

water erosion

Most often, water erosion occurs on mountain slopes, as a result of the runoff of rain and melt water. According to the intensity, the soil can be washed off in a continuous layer or in separate streams. As a result of water erosion, the top fertile layer of the earth is demolished, which contains rich elements that feed plants. Linear erosion is a more progressive destruction of the earth, when small gullies turn into large pits and ravines. When erosion reaches such proportions, the land becomes unsuitable for agriculture or any other activities.

wind erosion

Air masses are able to inflate small particles of the earth and carry them over great distances. With significant wind gusts, the soil can disperse in significant quantities, which leads to the weakening of plants, and then to their death. If a wind storm sweeps over a field that is just beginning to sprout crops, they can become covered with a layer of dust and be destroyed. Also, wind erosion worsens the fertility of the land, as the top layer is destroyed.

Consequences of soil erosion

The problem of land erosion is an urgent and acute problem for many countries of the world. Since the fertility of the land directly affects the amount of crops, erosion exacerbates the problem of famine in some regions, as erosion can destroy crops. Erosion also affects the reduction of plants, respectively, this reduces the population of birds and animals. And the worst thing is the complete depletion of the soil, which takes hundreds of years to restore.

Technique for protecting soil from water erosion

Such a phenomenon as erosion is dangerous for the soil, therefore, complex actions are required to ensure the protection of the earth. To do this, you need to regularly monitor the erosion process, draw up special maps and properly plan economic work. Land reclamation work must be carried out taking into account the protection of the soil. Crops should be planted in stripes and a combination of plants should be selected that will protect the soil from leaching. excellent method protection of the land will be planting trees, creating several forest belts, near the fields. On the one hand, tree plantations will protect crops from precipitation and wind, and on the other hand, they will strengthen the soil and prevent erosion. If there is a slope in the fields, then protective strips of perennial grasses are planted.

Soil protection from wind erosion

To prevent weathering of the soil and preserve the fertile layer of the earth, it is necessary to carry out certain protective work. To do this, first of all, they carry out crop rotation, that is, they annually change the planting type of crops: one year they grow cereal plants, then perennial herbs. Also, strips of trees are planted against strong winds, which create a natural barrier to air masses and protect crops. In addition, high-stemmed plants can be grown nearby for protection: corn, sunflower. It is required to increase soil moisture in order to accumulate moisture and protect the roots of plants, strengthening them in the ground.

The following actions will help against all types of soil erosion: