The middle course of the Ob and Irtysh. Ob with Irtysh
Gullies are a form of relief that looks like hollows with quite great depth, are formed, most often, when washed out with water. Gullies are considered a problem because they appear in unexpected places on hilly and flat terrain, deteriorate the condition of the soil, change the nature of the underlying surface, and also disrupt ecosystems. While some ravines can be several meters long, others stretch for kilometers. According to the age of formation, ravines are mature and young. To prevent their development, as soon as they are discovered, it is necessary to strengthen the soil: plant trees, introduce excess moisture. Otherwise, there is a possibility of losing entire hectares of fertile land.
Reasons for the formation of ravines
Experts identify a large number of reasons for the occurrence of ravines. These are not only natural, but also anthropogenic reasons. The main ones:
- farming;
- drainage of the river bed;
- water and wind erosion;
- destruction of the slopes of pits and other depressions in the ground;
- cutting down green spaces;
- plowing up plains, turning them into fields;
- lack of control over the regime of water bodies;
- accumulation of snow cover in winter;
- insufficient moisture in arid areas, etc.
Vegetation cover is the main protection against the formation of ravines in the ground. If people conduct any economic activity, as a result of which voids underground and ravines may appear, it is necessary to eliminate these causes: bury holes, level the soil, plant new crops, and divert water flow to another place.
Stages of gully formation
At the first stage, a pothole appears, the bottom of which is parallel to the surface of the earth. If the cause is not eliminated immediately, then the second stage begins. During it, the depression in the ground rapidly increases in size, the gulley becomes deeper, wider and longer. The cliffs become steep and dangerous.
After this comes the third stage. At this time, the ravine develops in the direction of the watershed. The slopes of the pothole become more wet, crumble and collapse. Typically, a ravine develops until it reaches the soil layer. At the fourth stage, when the ravine reached enormous size, its growth stops. As a result, this form of relief spoils any terrain. There is practically no vegetation here, and animals can fall into a natural trap, and many representatives will be able to successfully get out of it without injury.
Research
Subject:
FORMATION OF ROVIES
Performed:
Konovalova Sofia
4th grade student
MBOU secondary school No. 1, Saryg-Sep village
Head: Konovalova N.V.
CONTENT
1. Introduction. “Formation of ravines”……………………………………..2
2.Relevance of the topic……………………………………………………..3
3. Purpose and objectives of the work……………………………………………………4
4. Methodology for performing work…………………………………….5
5.Results……………………………………………………….6
6. Findings and conclusions…………………………………………………...7
7. List of references………………………………………………………8
8. Applications……………………………………………………………9
INTRODUCTION
Formation of ravines.
During excursions or in the summer, picking mushrooms and berries, we always pay attention to the beauty of the surrounding area. Any surface has a special beauty: completely flat, hilly, and mountainous. And we feel joy and pride for our native land. How beautiful she is!
But it also happens that instead of joy and pride, you experience a feeling of bitterness and resentment. For example, at an old, abandoned quarry. Once upon a time sand or clay was mined here. Now the quarry is like a huge wound on the surface of the earth. But people had to fill it up and build a field or plant a forest in this place. (Annex 1)
A tractor driver also acts very badly and uneconomically if he plows the ground on a slope so that the furrows go down along the slope. Streams of water will flow along these furrows after the first rain - this is the beginning of the ravine! Water flowing over the surface of the soil forms small temporary streams. They erode the soil even more, forming potholes in it, which over time turn into ravines. Gullies reduce the area of agricultural land, and soil erosion reduces its fertility. Yields on washed away soils are sharply reduced. Plowing can only be done across slopes. And steep slopes cannot be plowed at all. Unfortunately, these simple rules often violated.
1. Pleshakov A. The world around us, textbook 4th grade, 1 hour M.: Education 2002- p. 148.
RELEVANCE.
Why did we turn to the topic “Ravines”? There are quite a few ravines in our area. How are these ugly wounds of the earth formed?
In our village there is a favorite mountain called Uval. In the warm season, everyone loves to go there and pick mushrooms and berries; in winter, they go skiing down this high mountain. We noticed that over the course of several years, for some reason, ravines had formed along the road. And we decided to study why and where these ravines are formed, which cause great harm:
a) they make it difficult to plow fields,
b) reduce the area of fertile land,
c) disfigure the landscape of the area,
d) create a danger for people and animals (since ravines up to a meter wide can reach a depth of up to three meters).
We are surrounded by unique Tuvan nature, which we must preserve and protect.
GOAL AND TASKS.
Purpose: to study the reasons influencing the formation of ravines.
Objectives: 1. Observe the places where ravines form.
2. Determine how ravines are formed on different types soil.
3. Suggest ways to prevent the formation of ravines.
METHODOLOGY FOR PERFORMING THE WORK.
1. Study the literature on this issue.
2. Observe erosion and the formation of ravines in nature.
3. Conduct practical experiments with sand, clay, and soil.
4. Analyze the prospects for work to combat the spread of ravines.
RESULTS OF WORK.
Having studied the relevance of this topic, we decided to conduct experiments with various types soil They took sand, clay and earth.
Dry sand was poured onto the tray. Pouring water into the sand, we saw that the water was completely absorbed into it very quickly, until the sand became oversaturated with water. Then the water spread throughout the sand and began to stand on its surface.
Having tilted the tray, we began to pour water into the sand in a thin stream (Appendix 2). When the sand was oversaturated with water, the water began to very quickly make its way into a channel (Appendix 3), eroding it more and more, taking with it particles of sand, until the place where the water entered was washed out all the way to the tray (Appendix 4). The greater the slope of the tray, the faster the water runs along its bed and the more particles of sand it carries with it. We placed a barrier for water - a small pebble - in the place where the water broke through the channel. The water went around the stone on both sides and began to make new roads for itself. (Appendix 5). At the same time, the sand was quickly washed away down to the tray along the riverbed.
Similar experiments were carried out with clay and earth and they saw that water is absorbed into them much more slowly than into sand, especially into clay. The water almost immediately began to make its way into a small channel. (Appendix 6.7) When the tray was tilted, the water expanded the channel in width faster than in depth.
Having studied experimentally how ravines are formed, we decided to look in nature at what places they most often appear. It turned out that ravines are formed where grass (grass cover) is trampled or worn out, restraining and strengthening the fertile layer of soil.
Sandy soil degrades much faster than clay soil. Such ravines become wide and deep very quickly. Where in the beginning of a ravine there is sand under a layer of earth, the ravine is eroded from the inside and the layer of earth collapses down, thereby the fertile layers of the fields become less and less in area. (Appendix 8) Gullies that form in the middle of the fields make it difficult to plow the field and sow grain.
Gullies pose a great danger to people and animals, as a ravine up to a meter wide can reach a depth of up to three meters. And if you accidentally fall into such a ravine, you can be injured or even die. (Appendix 10).
FINDINGS AND CONCLUSIONS.
From the conducted research work We found out that ravines are formed for the following reasons:
1. Incorrect plowing of slopes.
2. Abandoned sand, clay and coal quarries.
3.Trampling of grass by humans, animals, and vehicles.
4. Erosion of the earth's surface by melt and rainwater.
During the work, we noticed that where the grass cover is not disturbed, ravines do not form. And the ravines, overgrown with bushes and grasses, do not spread further. (Appendix 11).
Therefore, we plan to study how we can prevent the formation of ravines, conduct educational work among school students in order to attract them to careful attitude to nature.
Working on this topic has enriched me with knowledge about nature native land, made me think about environmental problems, increased responsibility for caring for nature.
BIBLIOGRAPHY.
1.Brooks S. Geography of the Earth.-M.: Rosmen, 2000.
2. Dmitrieva I., Makrushina O. Lesson developments in the surrounding world. 4 grades – M.: VAKO, 2003.
3. Orlov B., Solovyov A., Shcherbakov B. Children's enc. T.1.M.: Education, 1964.
4. Pleshakov A. The world around us. Textbook 4th grade, part 1.M.: Enlightenment, 2007.
ANNEX 1.
SAND QUARRY.
APPENDIX 2.
FILLING A TRAY WITH SAND WITH WATER.
APPENDIX 3.
WATER BREAKS A BED IN THE SAND.
APPENDIX 4.
APPENDIX 5.
EXPERIENCE WITH AN OBSTACLE,
APPENDIX 6.
EXPERIENCE WITH CLAY.
APPENDIX 7.
EXPERIENCE WITH THE EARTH,
APPENDIX 8.
RAVINE.
APPENDIX 9.
RAVINE.
APPENDIX 10.
DEEP RAVI.
APPENDIX 11.
Federal Agency for Education
TOMSK STATE UNIVERSITY (TSU)
Faculty of Geology and Geography
Department of Geography
COURSE WORK
Gullies and the fight against them
(Discipline - Geomorphology)
Selezneva Natalya Vasilievna
Supervisor
professor, doctor geographer. sciences
A.M. Maloletko
Introduction
Formation and development of the ravine
Distribution of ravines
Development of gully erosion and its control
Conclusion
Introduction
Gully erosion is an active relief-forming process. The ravine - the uppermost link of the erosion network - develops over hundreds of years and, as a rule, is not destroyed under the influence of annual anthropogenic pressure. The immediate cause of the formation of ravines is the violation (for any type of economic use of land) of the natural conditions for the formation of runoff on the slopes of river valleys, gullies, dry lands, etc. A large number of ravines develop in cities, suburban areas, towns, during deforestation, mining and construction.
The negative role of ravines in to the greatest extent is determined by the destruction of land, engineering facilities, and communications. In addition to the loss of area due to the formation of the ravines themselves, the damage agriculture cause loss of arable land; their areas are almost three times larger than the areas of the ravines themselves. The ravines destroy utility and industrial buildings, roads, and power line supports. Currently, attention to ravines on the territory of housing construction is increasing due to the environmental problems of the territories adjacent to the ravines. The ravines were used as previously, and are still used now, for industrial and industrial landfills. household waste, which is often a threat to human health.
Modern technical means aimed at combating erosion processes can significantly limit the manifestation of gully erosion. At the same time, it is possible to use large ravine forms within the city for parks, recreational areas, rural areas for creating ponds in ravines and organizing pond farming. However, this requires a scientifically based understanding of the patterns of development of ravines, which will make it possible to determine the need for the use and appropriate set of anti-erosion measures.
It is extremely important to predict the maximum dimensions that a ravine can reach during its development, the rate of growth of ravines in length at individual stages, as well as obtaining indicators of the maximum possible gully infestation of territories. At present, territories have already emerged where, given the large modern gully, the potential for its development is practically exhausted and the emergence of new gully forms is unlikely. These circumstances must be taken into account when organizing anti-erosion protection of lands. At the same time, gully formation should be given increased attention, since the natural prerequisites for the development of gully erosion are very great. Opportunities for the development of ravines exist in the forest zone, provided that the vegetation and turf there are destroyed. soil cover, which is confirmed by data on the active growth of ravines due to clearings, ravines developing along forest belts in the forest zone, in the tundra during the development of oil and gas fields, in places of reindeer pastures, etc.
All these problems can be solved if there is data on the “potential” of the territory for the development of the ravine formation process. Therefore, the development of methods for assessing the potential of gully erosion based on experimental data, field observations and a model of gully erosion is the basis for designing anti-erosion measures, establishing their order and composition.
1. Formation and development of the ravine
Gully formation is a modern relief-forming process carried out by temporary channel flows of rain and melt water, as a result of which specific negative linear forms appear on the land surface. The formation of ravines is currently associated, as a rule, with the disruption of the existing natural complex under the influence of anthropogenic influence. However, their very development occurs according to the laws natural processes and depends on a combination of factors that largely determine the possibility of the emergence and activity of the subsequent development of ravines. This does not exclude the possibility of the emergence and growth of a ravine without anthropogenic intervention on large slope catchments under the influence of natural processes (undermining of a steep bank by a river, landslides, karst, etc.)
The main natural factors of gully formation are hydrometeorological and geological-geomorphological conditions: summer precipitation and water reserves in the snow cover before snowmelt, horizontal and vertical dissection of the territory by a valley-gully network, soil erosion, steepness and shape of the slopes of river valleys, blocks, dry lands, as the main centers of gully formation.
The ravine differs from other linear erosional formations - hollows, ruts, gullies, beams - in three main features: 1) characteristic dimensions; 2) typical form transverse and longitudinal profile; 3) dynamic state.
The ravine is characterized by a longitudinal profile, in the top part it has a slope significantly greater than the slope slope, and in the bottom part it is much smaller, often reaching zero values. In the vast majority of cases, alluvial cones of gully forms, if they emerge onto a river floodplain or at the bottom of a gully, are a typical accumulative form, rising above the marks of the surrounding surface.
The transverse profile of the ravine changes both in length and in time over the period of development. With active growth, the ravine along its entire length has steep, crumbling, landslide slopes, devoid of vegetation, the slopes of which significantly exceed the angles of natural repose. As the ravine develops, starting from its mouth, the slopes flatten and become overgrown. This process is most typical for humid zones; in other conditions ravines long time maintain steep bare slopes.
Distinctive feature the ravine is its dynamic state. A ravine remains a ravine as long as it is active or has not lost the ability to be activated due to changes in anthropogenic load or under the influence of natural factors. This distinguishes a gully from gullies. When a developing erosion incision of considerable depth appears in a beam, often cutting through the entire area of its bottom, it is called, in contrast to the beam form, bottom; ravine, emphasizing that exactly active development- a distinctive feature of the gully erosion form. (Lyubimov B.P., Timofeev D.A. 1998, p. 30)
The activity of development of a ravine at different stages is one of the problems, the solution of which is associated with the analysis of field and experimental data, which makes it possible to create an algorithm for the development of such an erosional form. The emergence of a ravine usually begins with the formation of erosion craters on the steep part of the slope, which then combine into a ravine. It, in turn, moving regressively upward as a near-summit ledge, deepens, clears the thalweg of soil material coming from the slope and eroded in the channel, and carries it to the lower sections of the slope or directly into the valley of larger parts of the erosion network. Already at the very beginning of the formation of a ravine, a cascade of ledges is observed in the channel, moving up the channel. The development of the ravine is carried out by the associated activity of regressive and transgressive deep erosion with the removal of erosion products and elephant deformations. At the beginning of development, the ravine bed is a purely erosional form; then, as the ravine lengthens, deepens and widens, alternating zones of erosion and accumulation begin in its bed. During the development of longitudinal and transverse profiles, accumulative complexes are formed first in the mouth of the ravine, and then the same complexes, but of smaller sizes, appear in the middle and even upper parts of the longitudinal profile. At the final stage of development, flow velocities in the ravine decrease significantly, approaching non-erosive levels and are insufficient to move slope material.
Based on the results of field studies and laboratory experiments in the natural complex “slope catchment - ravine”, the main connections were identified, the interaction of which constitutes the essence of the gully formation process. These are connections - external, intercomponent and internal.
Externalgully formation conditions include a complex of natural factors and the degree of anthropogenic impact on the landscape, as well as processes accompanying gully formation - collapse and shedding of soil on slopes, landslides, karst, suffusion, etc. External connections establish a relationship between the conditions in which gullies develop and their number, parameters and growth activity. Of the natural factors, the main ones are: firstly, the factors influencing the active force (flows of storm and melt water) are precipitation, filtration properties of soils, morphometry drainage basin, i.e. its size and configuration, depth of erosion bases, slope and shape of slopes; secondly, it is the susceptibility of soils to erosion and their anti-erosion properties.
Intercomponentconnections establish the relationship between the morphometric parameters of the ravine in the process of its development. Natural surveys of gully-beam systems and individual ravines even at large areas and in a wide range natural characteristics regions do not provide sufficient material for analyzing the relationships in the development of individual parameters of the ravine. The ravines, the development cycle of which, as a rule, exceeds a century-long period, at the time of the survey are in a development phase determined by previous processes. Observation cycles of 10–15 years, which is considered sufficient for a long period of time, usually falls on one of the phases of development, which does not allow us to identify a tendency for the growth of individual parameters to extrapolate patterns of change in the future.
In-componentconnections describe the internal patterns of development of the ravine as an erosional form. The main pattern that determines the development of the ravine as a whole is the presence of ascending and descending branches of development over time. The ascending branch corresponds to positive feedback during the period when the self-development of the ravine reaches certain point intensifies the process of growth of the gully shape. This is the period of formation of a linear incision, when a channel is formed that concentrates the runoff from the drainage area, and therefore the speed and, as a consequence, the eroding and transporting capacity of the flow increases. In the initial period, there is a gradual increase in the drainage area drained by the linear incision, and, consequently, the flow rate of water entering the channel increases. The gradual formation of a single channel with less gradation, and, consequently, with a gradually decreasing roughness, dates back to this time.
Under natural conditions, when the edge of a slope breaks through, especially during periods of significant floods or during rainstorms, an unusually rapid development of a pothole on the slope occurs, when in one season its length reaches 100–1500 m. Similar rates of growth of linear cuts in length have been recorded by a number of researchers not only in our country, but also abroad. IN scientific literature The possibility of destruction of arable land within several years due to gully formation is often noted. The case is exceptional rapid growth linear incision during the spring flood period was recorded by us on the slope catchment area of the river. Toyms (a tributary of the Kama River near the village of Tanayka). The consequences of the growth of the ravine were the destruction of the dirt road surface and the subsequent filling of the cut with soil washed away and moved from the garden plots.
Changes in the growth trends of the ravine, its slowdown in all parameters as the peak moves up the slope, are associated, first of all, with the transformations occurring on the slope catchment due to the development of the gully form itself, i.e. In the process of growth, a ravine modifies the catchment that gave rise to it. As the linear form develops, the flow from the state of an active, eroding force is transformed into a transport artery with speeds close to non-erosive, capable of transporting sediment from the overlying drainage area without eroding the bottom of the ravine.
Analysis of the complex of external, intercomponent and internal connections that determine the patterns of formation of ravines made it possible to identify stages of their development, differing mainly in the rate of growth. The main integrating parameter in this case is the volume of the ravine, changes in which correspond to changes over time in the volume of soil carried by the flow beyond the developing erosion form. A major role in determining the stage is played by determining the length of the ravine over time. At the same time, the growth rate of a ravine is inseparable from its morphometric appearance and is largely determined by the interrelations of the parameters of the ravine in the process of its development. At the same time, the identified stages of development are inherent in both modern, in the vast majority of cases, anthropogenic ravines, and natural modern erosional forms. There are four stages in the development of ravines.
Stage 1 - a ravine originates on a steep section of a slope catchment in the form of breaks in the turf, the formation of erosion craters, their merger, the formation of a gulley and the gradual concentration of a slope flow in a single channel. At this stage, the impact of anthropogenic factors, random intensification or cessation of linear erosion is great. The period from the formation of the erosion crater to the ravine is difficult to determine in terms of time. The beginning of the gully-forming process is clearly recorded from the moment the edge of the slope breaks through and the gulley transforms into a linear shape with a longitudinal profile typical of a ravine and dimensions that do not allow it to be destroyed by subsequent plowing.
Stage 2 - the most intensive growth of the ravine in all respects near the edge of the slope, especially its length and depth. The longitudinal profile of the bottom in the middle and mouth parts remains convex, which helps to increase the speed and, accordingly, the eroding and transporting ability and turbidity of melt and rainwater flows.
Stage 3 - the development of the length of the ravine is completely completed; the volume by the end of the stage is produced by 60–80%. The second and third stages are characterized by the most intense decrease in the rates of linear and volumetric growth, which is a consequence of a decrease in the near-summit catchment area as the ravine moves regressively up the slope. At the same time, the average slope of the longitudinal profile of the ravine decreases and it flattens out, transforming from convex to straight and convex-concave.
This stage ends the period of the most active growth of the ravine, corresponding to? 40% of the total time of gully formation.
Stage 4 - corresponds to the time of gradual formation of the longitudinal profile, its transformation from straight and convex-concave to “worked out”, a time of slow and relatively calm development. At this stage, alternation of processes and zones of erosion and accumulation is characteristic both in time and along the length of the ravine. The erosion profile associated with intense floods or rainstorms of rare frequency can become accumulative for many years.
This stage occupies 60% of the total time of ravine formation and is characterized by the ravine reaching its maximum size. If the identification of stages 2 and 3 is determined only by the intensity of the gully formation process and the nature of intercomponent connections, then at the fourth stage the characteristic dimensions of gully forms are most closely determined by a complex of external connections. Natural factors of gully erosion act as arguments in the dependencies for determining the dimensions of ravines at the final stage of development. It is they that determine the difference in the maximum possible gullying of territories, the different lengths of slope catchment areas affected by ravines under similar conditions and the time of development of the regions.
Taken together, the identified stages of gully formation characterize the features of the process of self-development of a ravine. The change in the process over time, considered by intracomponent connections, is unique for each of the parameters of the ravine shape; it is prepared by the process previous development and determines the nature of subsequent changes in the entire complex of parameters of the ravine - its length, width, depth, area and volume.
Distribution of ravines
The spread of ravines in almost all natural zones of Russia is indicated in the works of most researchers of gully erosion. The influence of natural characteristics on the appearance and development of ravines was studied under stationary conditions, during field surveys of territories, in laboratories, using cartographic materials and aerial photographs, using the methods of mathematical statistics and using all types of modeling. New data on ravines is attracting attention as a basis for anti-erosion measures, material for calibrating models of the gully formation process, and as a source of additional regional characteristics the spread of ravines, specifying for specific conditions the danger of their further development.
The formation of ravines is directly related to the development of larger parts of the erosion network (rivers, ravines, dry valleys). Analysis of the morphometry of the slopes of the valley-gully network and the conditions for the formation of runoff in the catchments of rivers, ravines, and dry valleys allows not only to identify the influence of natural and anthropogenic factors on the modern distribution of ravines, but also to obtain data to determine the development trend of the process. Analysis of the distribution of ravines on slope catchments along river valleys and the sides of ravines shows exceptional variability in the conditions of their occurrence and distribution. During field surveys of ravines carried out in 1970–1993. in the regions of the South of the Non-Black Earth Region (Oryol, Ryazan, Tula regions), the Black Earth Center (Kursk, Voronezh region), the Volga region (Kirov, Gorky, Saratov regions), Stavropol, Altai Territory, the structural features of the ravine network were noted and the location of ravines and the hierarchy of channel forms formed by temporary flows of rain and melt water on slope catchments were determined. Analysis of topographic maps of these regions with clarification and correction during field studies showed that one hundred drainage basins of ravine forms, despite the exceptional diversity of natural conditions, have common features of morphometric structure that distinguish them from gullies and river catchments. This is manifested both in the relationship between the length and area of catchment areas, and in the configuration features (changes in width along length) of erosion forms. The influence of the depths of local erosion bases on the planned characteristics of watersheds was also considered.
Patterns in the distribution of ravines on the territory of Russia were identified from maps compiled at the Research Laboratory of Soil Erosion and Bed Processes, containing data on the density and density of modern ravines and the area of ravines in terms of the percentage of losses land resources from the area of agricultural land. When calculating the indicators, gully forms with a length of at least 70 m were taken into account. Analysis of the maps revealed features of the distribution of ravines, reflecting both the results of anthropogenic intervention in the conditions of the formation of water flow on slope catchments, and the natural features of the regions. Research has confirmed a number of known factors in the development of the ravine formation process, the importance of natural factors and their anthropogenic disturbance. Based on the degree of infestation, the following types of territories are distinguished:
.Territory with a low degree of ravage. Where ravines are extremely rare and only single gully forms are found. The area of ravines, which is largely a function of their distribution in density and thickness, is also extremely small in these areas. Similar gully indicators are typical for the following two types of areas:
a) undeveloped or poorly developed lands with flat or ridged terrain; these are the northernmost regions of the European territory of the country - the tundra zone, the forest-tundra zone and the northern part of the forest zone. However, in these territories there are also heavily gully areas, which usually accompanies deforestation and anthropogenic development. Such areas are found on the territory of the Malozemelskaya and Bolshezemeskaya tundras, the Northern Uvals, the Vyatskie Uvals and in some other areas.
b) Flat lowlands with a very weak valley incision (the depth of dissection exceeds 10 m. Such territories include the Caspian lowland, Meshchera.
.Areas with a moderate degree of ravage. The area of these gully erosion areas does not exceed 0.5%. Against this background, small areas with higher infestation rates may occur. Such territories are typical primarily for sparsely populated and poorly developed areas with shallow relief dissection, as well as for lowlands of populated areas. This is a significant part of the forest zone south of 57?58 N, some areas are more northern regions, adjacent to the middle reaches of the river. Pechora, lower reaches of the river. Mezen, middle reaches of the river. North Dvina, smoothed areas of the Smolensk and Central Russian Uplands, Oka-Don Plain, Kuban Lowland, populated wide band along the western spurs of the Ural Mountains south of the river. Kama and some other areas.
.Territory with high degree ravages. A significant part of the forest zone belongs to this type of gully dissection. These are predominantly well-developed areas with relatively favorable conditions for gully formation, including fairly dissected and rugged terrain. Cover rocks are easily eroded and consist of silty sandy loams and loams, less often sands and loess-like loams. Such regions include central dissected sections of hills and ridges (Central Russian, Volga, Verkhnekamsk, Northern ridges, etc.), as well as undulating plains (Oka-Don, western part of General Syrt, etc.)
.Territory with a very high degree of ravage. These are areas of forest-steppe and steppe zones, long-standing and active agricultural development, almost completely plowed. They usually occupy deep, dissected, rugged parts of hills composed of silty and loess-like deposits. In these territories there are areas with more than 1.5% of agricultural land affected by gully erosion. Within the steppe and forest-steppe zones, the following areas are distinguished: the south of the Central Russian and sections of the Volga and Kalach uplands, the uplands of the High Trans-Volga region and some other smaller territories. Within the southern part of the forest zone, the most over-ravine basins are the basins of the Vyatka, Oka, Don, Kama rivers, as well as certain areas of the Smolensk-Moscow and Central Russian Uplands.
As can be seen, the intensity of gully erosion in all zones depends on both economic activity and the natural conditions of the regions. The leading role here belongs to the anthropogenic factor. This is what determines the intense modern erosion of the forest-steppe and steppe zones, where the plowing of the territory is about 70–80% total area. IN natural conditions a set of natural characteristics of the steppe and forest-steppe zones (soils, vegetation cover) prevents the development of gully erosion. Zonal natural factors contributed to the development of intense gully erosion in these zones, since their landscape features caused the first stage of development of territories for arable land, which contributed most to the development of ravines. At the same time, the very structure of zonal factors turned out to be disrupted. The climate remained unchanged - the only factor that in itself contributes to the development of the erosion process is the rainfall nature of precipitation, rapid snow melting.
The most important role in the distribution of ravines belongs to the relief - the azonal factor. The main relief indicators that influence all aspects of the process of gully formation include: the depths of local erosion bases, the shape and steepness of slopes, the areas of slope drainage basins, and slope exposure. The most expressive consequence of this influence is the maximum density and density of ravine dissection in elevated areas of the territory, for example, in the Central Russian and Volga Uplands. A detailed analysis of the influence of the morphometric features of drainage basins on the development of a ravine network is contained in almost all works devoted to the regional assessment of the ravine formation process.
Soil erosion has a great influence on the development of gully erosion, the spread of ravines across the territory, the intensity of the process, and the morphometric appearance of individual ravines. Often, the eroding speeds of flows determine the very possibility of developing ravines in the territory.
The main results of studying the distribution and development activity of ravines in different zones of the country are the following:
Gullies are common in all natural zones, which excludes the assumption that this process is characteristic of highly specific conditions, for example, the zonal nature of this phenomenon. It is well known that the forest-steppe and steppe zones are most gully-filled, but in the tundra zone, ravines are noted in Novaya Zemlya, Kolguev, Taimyr, Yamal, Bolshezemelskaya and Malozemelskaya tundra, in the Vorkuta region, especially in connection with the development of new oil and gas fields. In the forest zone, in almost all areas where lands that were previously in a natural state are being developed for agriculture, agriculture and industrial construction, gully formation is accompanied by disturbances of the natural landscape. In desert and semi-desert zones along river valleys Caspian lowland, in Ustyurt, along the Amu Darya, ravines are developing.
Despite the fact that ravines appear in all zones, their distribution is uneven. The predominant quantity, as noted by all researchers, corresponds to zones of active and long-standing agricultural development, and plowing of land is the reason for the most widespread appearance of ravines in the south of the forest-steppe and steppe zones. The transformation of the natural complex in these zones under the influence of economic activity led to “accelerated” linear erosion.
Of the natural factors of gully formation on the growth rate, size of ravines, their number and total length the greatest influence is exerted by azonal factors: morphometry of watersheds, geological structure and the dissection of the territory by a valley-gully network.
Gully erosion is a complex relief-forming process. The emergence and activity of development of ravine forms is determined by the entire complex of natural characteristics of the territories, i.e. There is no leading natural factor in the formation of ravines. The desire to highlight such a factor among others is due to the difference in natural conditions in the regions. For example, in the case when the gullying of a region is characterized, which has different erosion or filtration capacity of soils and soils, all other things being equal, one gets the impression of the “leading” influence of the geological factor. If we consider a region whose territory is dissected to varying degrees by a girder network, it is its presence that is considered as the main factor in the formation of ravines. The presence of elevated and flat areas in a particular region creates the impression of a “leading” geomorphological factor. At the same time, the general background of highly ravaged regions, associated, for example, with heavy rainfall or significant erosion of soils, can be relegated to the background. The diversity of natural conditions determines the variability of gullying within regions, and the quantitative characteristics of gullying (density and density of the network, size of ravines) are a function of the totality of all natural characteristics of the territories and the degree of anthropogenic impact.
The consequences of anthropogenic impact in different conditions and types of economic development are: the creation of additional runoff boundaries, concentrating the flows of melt and rainwater, redistribution of runoff in the catchment area, a decrease in the filtration capacity of soils and soils, and disruption of natural vegetation. In the overwhelming majority of cases, anthropogenic impact is a change in the parameters of all or part of the complex of natural factors of gully formation, the composition of which remains practically unchanged. Thus, the complex of natural conditions - factors in the formation of ravines - is the main determinant of the characteristics of the region's ravines.
3. Development of gully erosion and combating it
The development of the upper links of the erosion network in the form of gully forms is largely associated with the anthropogenic transformation of landscapes. Recognizing the negative impact of ravines on many sectors of the economy associated with the destruction of natural vegetation, turf and soil cover during mining, plowing, construction, etc., it must be remembered that ravines, in the number and size that they exist in present time, generated by human activity. Man has provoked all the negative consequences that the process of gully erosion generates. Since anthropogenic interference in natural landscapes, leading to the development of ravines, is not one-time, the process of gully formation turns out to be essentially irreversible. Humans create and maintain changes in the natural characteristics of slope catchment areas, making them favorable for the development of upper-order linear erosional forms, in particular ravines.
Gully formation, by the nature of its negative impact, differs from many natural-technogenic processes. The development of ravines, as a rule, does not entail those consequences that are commonly called catastrophic, associated with human casualties, major destruction, decommissioning of industrial facilities. At the same time, it is known that even terrible earthquake, volcanic eruption, inundation of land during a flood allows the exploitation of exposed emergency situations territory until the possible next occurrence of catastrophic events. Therefore, when predicting the danger of such phenomena, predicting their recurrence is so important. The formation of a ravine on a slope catchment is the process of irreversible removal of slope material and its deposition on the bottom of a ravine, on a floodplain or in a river bed. Stopping the development of gully erosion requires significant investment and a clear understanding of the further possibilities of the gully formation process, which depends on the natural features of the region and the type of development of the territory. After the end of active growth, a ravine remains, as a rule, a “negative” object. The type of development of the territory determines the assessment of the damage caused, the costs of anti-erosion measures or the transformation of ravines into recreational areas and, ultimately, a general understanding of the place of the development of ravines in the creation of a modern landscape.
With the current intensity of anthropogenic load on natural complexes there is a need to develop common criteria and uniform indicators to characterize the consequences of adverse natural, natural-anthropogenic, technogenic-natural processes, as well as to develop methods for quantitative assessment of such concepts as reliability, danger, vulnerability, risk.
In technology, “reliability” refers to the probability of failure-free operation. When assessing natural processes, a “failure” can be considered any consequence of a process that has a negative impact on the natural landscape or economic activity. For areas susceptible to the development of gully erosion, this is always loss of land, destruction of construction sites, etc. Such a “failure” can be assessed both in quantitative terms of direct land losses and destruction, and in their monetary terms. In my opinion, the concept of “danger” is not a quantitative category. This term refers to the very fact of the possibility of developing the process of gully formation in the territory. A quantitative characteristic of the “danger” is the “vulnerability” of the territory to the factor of gully erosion, which is a function of certain landscape conditions, the entire complex of natural characteristics used in calculating the potential of gully erosion.
Thus, according to the above definition, the calculated indicators of gully formation potential are a characteristic of the “vulnerability” of the territory. The relationship between danger and vulnerability can be represented as follows. We consider two territories of the same area, located in different natural conditions, but dangerous from the point of view of gully formation. On one, the potential for damage to the area is 5%, on the other - 2%. This share of the area can be called vulnerability to gully erosion in terms of area loss. Let's assume that modern defeat territories, gully erosion is the same and amounts to 1%. If we use the concept of “probability” of the process as the ratio of the area affected by ravines to “vulnerability”, then the territory with less vulnerability has a greater probability of damage - 0.5 versus 0.2 for the first territory. (Zorina E.F. 1987, p. 65?66)
The probability of realizing the potential in time can be called the “risk” of the development of the process. Assessing the degree of risk of adverse natural and man-made processes has a number of common features and concepts. The most appropriate period of time for calculating the risk of a natural process is a year. If the probability of a process characteristic is affected by a change natural parameters or the intensity of anthropogenic load, affecting changes in process activity over time, it is necessary to use materials in shorter periods of time. This helps to correct the averaged annual characteristics obtained from the processing of cartographic materials, aerial photography data, or actual observations of an object over long periods of time. Such a correction is advisable in relatively small areas when developing specific land use projects. For averaged characteristics, especially when cartographic interpretation of the degree of risk on small-scale maps used in determining the potential for regional level, the average assessment of this indicator over a long period is more appropriate.
Risk, a term that comes from technical literature, seems to fit well into natural Sciences and will be appropriate when analyzing natural processes. In any case, it reflects the patterns inherent in the development of the gully-forming process, especially in the part where it concerns the analysis of the gullying of the territory.
The use of the term “risk” for area losses is most appropriate for comparison with damage from other types of natural and man-made processes. Directly for gully formation, the concept of risk is conveniently considered in different options: applied to the appearance of ravines on a slope catchment, their annual number, and the annual increase in the length of the gully network. At the same time, it is advisable to consider the risk of increase in length separately for ravines that are at different stages of development. Averaging this indicator for all ravines in the territory is incorrect. The risk of increasing the number of gullies per unit length of the erosion network or the risk of lengthening the erosion network may be considered.
As the use of land resources intensifies, a certain attitude has developed towards the process of gully formation, which can be described as “the fight against gully erosion”. Unlike streams and rivers, which are considered as a natural value that must be protected, kept clean, the exploitation of which brings certain benefits and benefits to living organisms, the appearance of a ravine is a negative phenomenon. The fight against the formation of the upper links of the erosion network, such as potholes and gullies developing in fields, usually ends in human victory. Annual plowing almost always removes last year's traces of erosion from the rill network in the fields. Gully erosion for a long time, and often now, is considered as a link in erosion forms, which, having appeared as a result of anthropogenic intervention in natural landscape, can be destroyed if its negative effects are identified.
Associated with this idea is the application to ravines, their appearance and development, of a “crisis situation,” a concept introduced in the assessment of natural-technogenic processes. The onset of a period of “crisis” with a certain sequence of events, divided into stages, is preceded by stages of pre-crisis development of the process.
The advisability of considering the stages in gully formation is dictated by two main points:
) stage is a period determined by an assessment of the intensity of development of a ravine and the interaction of its parameters in connection with the use of a set of measures to limit the negative consequences of gully formation or prevent it.
) the identification of stages of development of ravines is associated with economic criteria. The economic feasibility of anti-erosion measures depends, on the one hand, on the method of using land resources and the cost of products produced on the land plot, which may be subject to the process of gully erosion, and on the cost of the anti-erosion complex, on the other. The identification of stages and their main features involves the use of certain concepts traditionally used in the study of the patterns of development of living nature.
For ravines, this is justified by the fact that they themselves exist only in the process of development - this is an active erosion form. These concepts include:
) the possibility of the initiation of a process, determined by the conditions ensuring its development. For example, with gully formation, this is, first of all, the presence of a natural catchment area, concentrating surface runoff and forming flows moving at speeds sufficient or exceeding the speed of erosion of slope deposits (soils and soils);
) the maximum permissible load on an area, which in living nature is determined by the possibility of maintaining life. In gully formation, this is the provision of water flows and slopes of the slope catchment area sufficient for the formation of a ravine. The load rate in the regional plan is determined by the minimum area of the drainage basin on which a ravine can form.
The potential for gully erosion can be assessed at the level of a specific catchment area in which the gully form develops, at the level of catchment areas of a gulley-dry valley network, or small river, the slopes of which are the main place for the development of ravines, and at the regional level. The set of indicators for it varies depending on the level of definition.
The formation of ravines causes damage to all sectors of the economy that are in one way or another connected with land use. This is most clearly manifested in relation to agricultural lands in the form of direct losses of arable areas and the dismemberment of slope catchment areas. Damage from ravines in civil, industrial and road construction, and during mining is significant. Gully formation potential data providing insight into possible devastating consequences process, make it possible to reduce, and in many cases prevent, further development of the upper-order erosion network, fragmentation of watersheds and reduction in the length of the slopes of the erosion network.
The impact of gully erosion on ecology natural environment varied. Its impact is manifested not only during the immediate period of the process, but also as a result of the dismemberment of the territory by a ravine network after the completion of gully formation. As well as for assessing a number of negative natural and natural-anthropogenic processes, for gully erosion the concept of the risk of ravines and the crisis situation in the territory can be applied.
At the same time, for many species of animals and plants, large ravines serve as natural reserves, where many plant species are preserved and representatives of the animal world thrive. The gully network, which is one of the many forms of linear erosion, along with large and small rivers, gullies and hollows, should be perceived as an equal element of the modern landscape.
Conclusion
Gully formation is a modern relief-forming process, as a result of which specific, negative linear forms are formed on the land surface. They are the result of the erosive work of temporary flows of storm and melt water on slope catchments, in the bottoms of gullies and dry valleys and along the sides river valleys. Distinctive Features The most typical slope ravines for the Center of Russia are: a) morphometrically expressed in relief catchment area and certain dimensions of the erosion form; b) the longitudinal slope of the thalweg in the lower part of the ravine is significantly less than the slope slope, in the upper part it exceeds it; c) ravine - an erosional form that is currently in development or has not lost the ability to continue growing in modern natural conditions.
The cause of gully formation is anthropogenic, or less often natural, interventions in the conditions for the formation of water and sediment runoff on natural slope catchments. In relation to the process of gully formation, the concept of essential capabilities of the territory for gully formation is introduced, as maximum amount and the maximum dimensions of ravines that can be formed when the natural hydromorphometric characteristics of slope catchment areas are disrupted.
Having begun under the influence of anthropogenic intervention, gully formation is subsequently determined by a complex of natural characteristics. A model of gully formation has been developed, according to which the potential of the process is determined, which is a quantitative characteristic of the parameters of the maximum gullying of territories. The potential, as a function of natural characteristics, varies from region to region. The modern gully represents the fully or partially realized potential of gully formation.
The structure of the modern gully network and the distribution of water flows along streams from ravines to large gullies differs from both the river and stream networks of the regions.
From its origin on a slope to reaching its maximum size, the ravine goes through four stages of development, in each of which it is characterized by certain morphological parameters, the intensity of the process, patterns of changes over time in volume, length and width, and other parameters.
List of used literature
gully erosion anti-erosion
1.Zorina E.F. Gully erosion: patterns and stages of development. - M.: GEOS, 2003, ? 170 pp.
.Zorina E.F. Some features of the development of gully erosion // Geomorphology. 1987. No. 4. P. 62?67.
.Lyubimov B.P., Timofeev D.A. What is a ravine? // Geomorphology. 1998. No. 2. P. 28?31.
.Lyubimov B.P., Moryakov L.A. History and forecast of the development of the ravine studied in late XIX century // Geomorphology 1984. No. 3. P. 54?59.
.Nikolskaya I.I., Kovalev S.N. Methodology for determining the intensity of ravine growth // Geomorphology. 1993. No. 3. P. 66?75.
Tutoring
Need help studying a topic?
Our specialists will advise or provide tutoring services on topics that interest you.
Submit your application indicating the topic right now to find out about the possibility of obtaining a consultation.
ravines They are deep potholes that arise as a result of erosion processes and flow into dry valleys or into the beds of permanent watercourses (streams and rivers).
Basis of erosion– the horizontal level from which erosion began and beyond which destruction cannot occur.
Figure 1 – Scheme of a growing ravine.
There are entire systems of small ravines that successively join as branches to the main, deeper ravine, which in turn flows into the bed of a permanent watercourse.
In the longitudinal profile, the bottom of the ravine does not have a uniform slope. Its upper reaches (beginning) are always an almost vertical cliff. The bottom of the ravine has a very steep slope for some distance; further, in the middle and lower parts of the ravine, the bottom slopes become more and more gentle.
In cross-section, ravines have a flat or slightly concave bottom and, in most cases, steep side slopes. In loess, loess-like, clayey and dense sandy-clayey rocks, the side slopes of ravines on greater depth retain almost vertical outlines.
The bottom and soles of the side slopes are most exposed to the erosive action of water flows passing through the ravine. The erosion of the bottom at the mouth of the ravine continues until its bottom coincides with the level of the lowest water horizon of a permanent watercourse or the bottom of the dry land into which the ravine flows. The growth of a ravine in length stops only when the erosion of its top stops.
Along with the deepening of the ravine, it widens due to the destruction of slopes by washouts, screes and landslides. The development of a ravine stops if its bottom and slopes begin to become covered with vegetation. Such extinct ravines are called gullies.
The presence of ravines in urban areas significantly complicates the planning of the city, leading to:
a) to the loss of development sites;
b) to the dismemberment of the urban territory, which complicates transport and pedestrian communications between individual areas of the city;
c) to surface drying of the soil that is undesirable for green spaces and a decrease in the groundwater level in the area adjacent to the ravine.
Each ravine is like a drainage, receiving soil and groundwater from surrounding area. In addition, ravines clog river beds with eroded soil. This creates a threat to the stability of buildings, roads, bridges and underground pipelines located near ravines.
Causes of gully formation.
Gullies serve as collection and drainage sites for surface water; their growth rate in width and length depends on the degree of soil stability against erosion. Gullies are formed as a result of erosion processes; in most cases, these processes occur intensively and in a short time cause destruction of the slopes of the ravine. In sandy soils, surface water is quickly absorbed without causing gully formation; on the contrary, in loess, loess-like loams, and clayey and loamy soils, ravines grow quickly.
The process of development of ravines is facilitated by: cutting down plantings along the slopes and in the basin of ravines, plowing and mining of clay and sand on steep slopes, lack of regulation of surface runoff, especially in the presence of abandoned ditches, etc.
Climatic conditions certainly influence the formation of ravines, in particular cold, long winters with deep freezing of the soil and accumulation of thick snow cover. All this leads to the formation of cracks in soils and their destruction. When snow melts, intense and abundant water flow into these cracks causes the formation of potholes. In arid areas, intense drying and cracking of soils can also cause cracks in the ground.
Stages of development.
- stage of a gulley or pothole up to 0.5 deep, less often up to 1 m, V-shaped. Streams of melt and rainwater are usually concentrated in it. The longitudinal profile of the ravine follows the profile of the slope on which it formed.
Struggle. It is enough to smooth out a shallow gulley (by plowing or smooth it out manually or road cars) sow with perennial grasses so that meltwater flows and storm water would flow over a turfed surface that is resistant to erosion. For deeper gullies, bottom structures are used - wattle-dams made of living willow stakes and fascines.
- The second stage is the stage of accelerated cutting into the ravine by the top. The longitudinal profile of the bottom gradually deviates from the profile of the slope, but is still very different from the equilibrium profile. The depth of the ravine becomes greater, the slopes become steeper, and its triangular shape begins to turn into a trapezoidal one.
Struggle— fast-flow trays, bottom structures: fence dams, afforestation.
- The third stage is the stage of developing a longitudinal equilibrium profile. The ravine cuts down to the base of the elephant, the shape of the transverse profile becomes trapezoidal, and growth noticeably slows down.
Struggle. bottom structures are not important.
- The fourth stage is the stage of attenuation, the transformation of the ravine into a beam or ravine. The longitudinal profile and slopes reach some equilibrium, level out, become turfed, and overgrown with bushes.
Struggle. It is necessary to regulate the meandering of the flow in the ravine bed with bottom structures so that melted and rainwater did not wash away the walls of the ravine. In addition, it is necessary to promote the speedy overgrowing of the slopes of the ravine with tree, shrub and herbaceous vegetation.
Waterfall – outstanding a natural phenomenon. A huge number of tourists often come to the cliffs in the river bed, where a stream of water falls from a height. Where are the other holy places where there are never so many pilgrims! The Niagara, Victoria, and Iguazu falls are known to everyone.
Few travelers who come to famous (and not so famous) waterfalls know that waterfalls destroy themselves. A turbulent stream of water wears away even the most hard rock. A steep cliff becomes less steep over time. The waterfall seems to “retreat” to the source of the river. In the future (this is in millions of years), the cliff will smooth out and the river will flow more calmly.
Similar processes are taking place in Russia. These processes lead to the formation of ravines. But they happen much faster. A ravine can appear, grow and “die” within the lifetime of one generation.
Where do ravines appear? They usually occur in forest-steppe and steppe zones. Gullies appear where they go heavy rains or where the snow cover is high in winter. This is the first condition for the formation of ravines. The second condition is natural slope, along which a stream of rain or melt water will roll down. The third condition is the presence of soft and easily eroded soil, not secured by plant roots, which the flow of water captures and carries away with it.
How do ravines appear?
At the first stage, a ravine or pothole appears. This is a small (30 - 50 cm) depression. The bottom of the gulley is parallel to the surface of the slope. A water stream flowing down the slope encounters a ravine on its way and gradually deepens it. The water rushing down erodes the upper part of the ravine, taking the soil with it, and the ravine expands, as if growing. In literally 1–3 years, in areas where there is arable land or loose soil, a deep ravine, as tall as a person, appears.
In the second stage, the ravine grows and expands. Since the top of the ravine is steeper than the surrounding surface, it is more easily washed away by the flow of falling water. As it blurs, the cliff wall collapses. Blocks of soil that have fallen to the bottom are washed away by the flow of water. The crushed soil is carried down the ravine bed by the current. The cliff rises and at the same time moves towards the watershed, for example, to the top of a hill or knoll. At the same time, the cliff rises more and more above the bottom of the ravine. Its height can reach 10 or even more meters. The flow of water flowing down the ravine pushes down the mouth of the ravine. But the lowest level has not yet been reached. Therefore, a basin is formed at the mouth where water can stagnate. The eroded soil is also carried here. At the second stage, the slopes of the ravine are high and unstable. With any heavy rain or under the influence of a flow of melt water, they can collapse down. Climbing such slopes is dangerous.
At the third stage, the ravine stops its development. The mouth of the ravine reaches the lower level, to which the waters eroding the ravine tend to reach. This level could be, for example, a river or stream. In this case, the slope at the mouth of the ravine becomes small. Now the water is slowed down by friction with the ground, and the force of gravity on an almost horizontal surface does not drive the water as before. The speed of the water flow is almost zero. Water will no longer be able to transport soil particles and it will begin to accumulate at the mouth of the ravine in the form of sediment. The resulting sediment zone expands and moves to the top of the ravine. At the same time, the depth of the ravine and its slope decrease. The slopes of the ravine collapse, the ravine expands, and its bottom expands. Now the water stream that flows along the bottom of the ravine has enough space to flow calmly, meandering, bypassing the obstacles it encounters.
Finally, at the fourth stage, the ravine completely stops growing. Within a few years, the slopes of the ravine become gentle enough to no longer collapse. A few more years, and the slopes of the ravine will be overgrown with plants and even trees. The ravine turns into a hollow or a beam.
Gullies harm agriculture by reducing the area of arable land. As ravines grow, they damage roads, cause landslides, and damage infrastructure. There have been cases when ravines collapsed during heavy rain along with the houses standing on their edges. Therefore, the growth of ravines should be prevented in every possible way. This can be done at any stage of development of the ravine by stopping the flow of water into it. This is achieved by constructing simple hydraulic structures and planting special forest belts along the ravines that absorb excess water.