From the history of the well. Unique pagan sanctuaries discovered in the Nizhny Novgorod taiga. A strange find on “Robber Mountain”

3. Tactical terrain classification

Tactically, the terrain is divided into:

According to traffic conditions;

According to the conditions of observation and camouflage;

According to the degree of intersection.

According to cross-country conditions the area may be:

Passable terrain almost does not limit the speed and direction of movement of tracked vehicles, allowing repeated movement along the same track. The movement of wheeled vehicles of normal cross-country ability is somewhat difficult.

Difficult terrain accessible for tracked vehicles, but at a lower speed than on passable terrain. The movement of wheeled vehicles of normal cross-country ability is almost impossible. Difficult terrain has a negative impact on the speed and ability of movement of police officers when performing service and combat missions.

Impassable terrain inaccessible for the movement of tracked and wheeled vehicles without work on laying column tracks.

According to the conditions of observation and camouflage, the area is divided:

Open area is a flat or slightly hilly treeless area, up to 75 % the area of ​​which is clearly visible from commanding heights in all directions.

Semi-closed area is transitional from open to closed. The area occupied by natural shelters is about 20% , from commanding heights visible to 50% area. Provides good camouflage for police officers and criminals.

Closed area is an area covered with forests, shrubs, gardens, with frequently located settlements, with mountainous, hilly or flat terrain. The area occupied by natural masks is 30% or more, and the area viewed from commanding heights is less 25%.

In closed areas, observation, orientation and target designation, control of forces and means of internal affairs forces and organization of interaction are difficult. A closed area is an ideal place for criminals to hide.

According to the degree of intersection with ravines, gullies, rivers, lakes, ditches and other natural obstacles, the terrain is:

Rough terrain has a small number of natural and artificial obstacles and is easily overcome by combat and special equipment in any direction. Natural obstacles take up less space on it 10 % area. The relief is usually flat, less often hilly. The terrain provides good visibility and the use of technology in all directions.

Moderately rough terrain has about 20 % area occupied by natural obstacles. In such terrain, the massive use of technology is difficult. The relief is usually hilly, less often flat. Such terrain contributes to protection from the damaging factors of nuclear and conventional weapons.

Rugged terrain It is distinguished by a large number of difficult obstacles - mountains, ravines, gullies, rivers, canals, ditches and swamps. The area under natural obstacles is more than 30 %. It is characterized by mountainous areas, territories with gully-gully and valley-gully topography. The use of technology is possible only in certain areas. Such terrain makes it difficult to conduct special operations and search for criminals.

Caused by the runoff of scattered streams of water, gully erosion occurs when these streams are concentrated into relatively powerful water flows. This concentration occurs when water flows from the slopes of the catchment into a natural hydrographic network or into an artificial depression. Such hollows are formed as a result of plowing along the borders of fields, as well as along arable furrows and road ditches. A water flow, if it has a sufficiently large destructive force given the existing slopes of the earth's surface, washes the channel along the bottom of a hollow or beam, and carries soil and soil into rivers and seas. Since the surface runoff of melt or storm water is periodically repeated, the ravines continue to grow in depth, length and width every year. Hence, a ravine is a negative landform formed relatively recently by periodically flowing water flow. In the ravine it is necessary to distinguish top, mouth, cone removal, bottom, edge And slopes.

On the left is a diagram of the ravine. Designations: a - top; b - screwdrivers; c - edge; g - thalweg; d - slopes; g - alluvial cone; g - beam edge.
On the right are types of ravines. Designations: b - primary coastal and secondary; c - apical; d - bottom; g - beam; a - watershed line; g - hollow; g - field boundary; arrows - water flow.

The ravines are confined to the hydrographic network. Each link of this network has a bottom, banks and slopes of a drainage area. By origin, ravines are divided into primary And secondary. Primary include ravines that first cut through new surfaces of the earth, secondary include ravines that deepen the existing hydrographic network.

Primary ravines, as a rule, are formed as a result of the concentration of water flow through artificial hollows on the slopes of the catchment area of ​​some element (beams, etc.). A concentrated flow of water, rushing through such a hollow down the slope, ultimately breaks through to the shore of a gully or river valley and erodes it. Here the primary ravine begins its development. Therefore, primary ravines are also called coastal ravines. Since these ravines subsequently, as they develop, penetrate into the adjacent slope of the drainage basin, they are also called slope ravines. More precisely, they should be called primary slope ravines.

Secondary gullies are formed as a result of erosion and deepening of the bottom of the hydrographic network, which is why they are also called bottom gullies.

Gullies growing along the bottom of hollows located at the tops of gullies and hollows are called summit gullies. In addition, it is necessary to highlight the ravines growing along the bottom of the side hollows. They begin their development on the bank of the gully and then move up along the water-supply hollow, dismembering the slope of the gully's catchment area. These ravines can be called secondary slope ravines.

The rate at which a ravine grows in depth is determined by the kinetic energy of the water flow and the resistance of the soil to erosion by water. When these forces are balanced, the growth of the ravine in depth stops. All other things being equal, this can happen either when the mass of flowing water decreases, or when the flow speed decreases due to a decrease in the longitudinal slope of the channel bottom.

Let us consider the reasons for the formation and characteristics of the growth of primary ravines. The most typical case is the formation of a primary ravine along the border of a field or road that is not laid correctly relative to the slope. Along such a boundary, as a result of plowing, an artificial depression is formed, which intercepts small streams of scattered runoff from the overlying slope and concentrates them into a more powerful water flow. This water flow reaches the shore of the gully (hollow), where the surface slope increases sharply. At the same time, the speed of the flow and its destructive power increase, resulting in soil erosion. A ravine is formed on the bank of the gully, which grows annually down its bank and up the slope.

On October 27, 2017, the next episode of “Field of Miracles” was released on Russian screens, dedicated to the theme “Forest”. In this program, players and television viewers were asked to guess the ancient and almost forgotten names of impassable or dense types of wooded areas. Let us remember them, and also consider which of the impenetrable forests were not mentioned in that issue.

What is a forest

Before understanding its special types, it is worth remembering the meaning of the term “forest”.

In a broader sense, this is the name given to an ecological system in which trees are the dominant life form.

If we interpret this concept in simpler terms, then this is the name for large areas of land densely covered with trees.

Types of woodland

Forests are classified according to different criteria:

• Origin - natural (virgin, spontaneous, economic) and artificial.
• The age of the trees.
• The composition of forest-forming species is coniferous, deciduous, mixed.
• Form of ownership.
• Place of growth (according to climatic geographical zones) - tropical, subtropical, temperate forests.

Also, depending on the density of trees, sparse forests (the so-called light forests) are distinguished as closed and sparse.

In addition to those listed, there are also such species as evergreen (wet tropical, coniferous or hard-leaved) and deciduous (deciduous in the temperate zone, monsoon, dry tropical deciduous), as well as semi-deciduous and mixed.

What is an impenetrable forest?

Having examined the basic typology of wooded areas, it is worth finally finding out the main thing - what impenetrable forests are.

From the very name of this term it is clear that this is the name given to those in which the density of trees, shrubs and other plants is too dense (closed), which prevents free movement through them. Because of this feature, such an impenetrable forest is also called dense.

Jungle as an example of an impenetrable forest

Oddly enough, but a classic example of this phenomenon is the jungle. This is the name given to impenetrable forests in the tropics and subtropics.

The main plants inhabiting them are not trees, but tall grasses and shrubs, tied with numerous vines.

Trees are represented in the minority in such impenetrable forests. These are mainly fast-growing softwood species.

Wilds. Thicket and Pushcha: what do these words have in common and how do they differ from each other?

However, impenetrable forests can be found not only in the tropics and subtropics, but also in temperate zones. Judging by the number of synonyms for this concept, there were also many of them on Russian lands.

One of the most famous is the word "wilds". In addition to it, people who speak Russian associate a dense impenetrable forest with two others: thicket and forest. Moreover, many believe that both terms mean almost the same thing. But this is not entirely true, since they have different shades of meaning.

A thicket is a difficult-to-pass closed forest or thicket. It is derived from the word “frequent”, that is, in such an area trees grow very close to each other. It is for this reason that such a place is quite dark compared to a sparse forest.

Pushcha is an impenetrable virgin primeval forest. This means that no human has ever set foot in it, thanks to which its own unique ecosystem, including rare breeds of animals, birds and plants, could be preserved.

By the way, the noun itself was formed from the words “empty” and “neglected” - that is, a place where no human foot has stepped.

Unfortunately, there are very few real forests left today. That is why this name for an impenetrable forest with windbreaks and perennial thickets is today more often used as a complete synonym for the word “thicket.”

However, the possibility of the emergence of new forests cannot be ruled out. So, for example, after the explosion at the Chernobyl nuclear power plant in 1986, most of the surrounding lands within a radius of 30 km were declared a contaminated zone and all its inhabitants were evicted. Fearing radiation, human beings almost never come here, but animals, unafraid of hunters, have bred in huge numbers. The same goes for plants and trees. Thanks to this, in thirty years the Chernobyl forests have become a miraculous wildlife reserve, and if they remain so in the next few decades, they can rightfully be called a forest.

What is the name of a dense impenetrable forest littered with windbreaks, according to V. I. Dahl’s dictionary?

The nouns “wilds”, “forest” and “thicket” are familiar to almost everyone and continue to be actively used in speech today. But in the Russian language there are outdated names for dense impenetrable forest, windfall.

The word is "slum". Today, for most of us, it is a term that means "poor residential areas or criminal dens." However, initially the word meant an impassable thicket.

One of the proofs of this is the existence of this term in the “Explanatory Dictionary of the Living Great Russian Language” of 1863, written by V. I. Dahl. Even earlier, this name was recorded by the Academic Dictionary of 1847.

Interestingly, according to Dahl, a slum is a “dense impenetrable forest” or a deep overgrown ravine, as well as any depression, depression, or cramped impassable place.

By the way, in the second round of “Field of Miracles” on October 27, 2017, this particular noun was guessed.

What was an impenetrable forest with ravines called in the old days?

Continuing to consider the types of impassable forest terrain given in the “Field of Miracles”, it is worth paying attention to the issue of the final game.

It asked about the ancient name for a forest with ravines or an impassable area.

As surprising as it may be to realize this, our ancestors called such a place the word “infection”.

Why is that? Perhaps the etymology of this term will help to understand this. And it was formed from the verb “to infect”, which in turn arose on the basis of the word “to strike” in the meaning of “wound”, “break” or “stab”.

Probably, the impenetrable forest with ravines was named so because the person who got out of there looked like he had been beaten pretty well.

By the way, it is possible that the habit of using the word “infection” as a curse word could also be associated with this particular interpretation of it, and not with the name of the infection.

Siberia and taiga - what is it?

Having learned what word in the old days used to call a forest, ravines and impassable terrain, it is worth considering two more terms that our ancestors used to call impassable wilderness.

One of them was made in the third round of the same issue, “Field of Miracles”. We are talking about a word that in ancient times called a forest swampy thicket overgrown with birches. It turns out that the noun is “Siberia”. Scientists believe that such a name came to Russian from the Mongolian language.

And the last of the names of the impenetrable forest under consideration is the noun “taiga”, which is well known to many.

This is the name given to a strip of wild, impassable or completely impassable jungle. Moreover, unlike those listed above, we are talking about coniferous, and not deciduous, areas.

There are dark coniferous and light coniferous forests of this kind. In the first of them spruce and fir trees grow predominantly, in the second - larches, pines and cedars.

Sometimes deciduous trees can also grow in the taiga. These are mainly birch, rowan or bird cherry trees.

Bwindi National Park in Uganda

Considering the various impenetrable wilds, one cannot fail to mention the Bwindi National Park. The peculiarity of this place is that its visitors have the opportunity to visit an almost virgin forest and enjoy observing wildlife that has hardly been affected by humans.

However, it is worth remembering that many dangers await tourists in the impenetrable forests of Bwindi, because many plants can be poisonous, and the forest inhabitants are not at all friendly. Therefore, this vacation spot is suitable only for people who are ready to face dangers.

Good evening, dear readers of the Sprint-Answer website. The TV game “Field of Miracles” is on on Channel One, because today is Friday. On the site you can find all the answers to the game "Field of Miracles" for October 27, 2017. And in this article you can learn more about the task for the final round, as well as find out the correct answer to the question in the final round. And the Super Game is ahead!

What did they call a forest with ravines and impassable terrain in the old days?

There are answers to this question on the Internet, because this question is often found in crossword puzzles and various quizzes. Rus' has always been famous for its forests and thickets. And the forests were impenetrable and dense. If a person ended up in the forest, then not everyone came out of it. In the old days they said about an impenetrable forest "infection" . Here's what you can find out about the word "Infection" on Wikipedia.

• Infection is a polysemantic term.
• An infection is a pathogen spread by microorganisms.
• Zaraza is a drink made from fruit juice in Mexico.
• Zaraza is a locality in Venezuela.
• Contagion is a geographical appellative denoting a difficult place. This is how the name of the city in the Moscow region - Zaraysk - is usually explained.

Here are the possible origins of the name of the city of Zaraysk.

• The name of the city comes from the Old Russian word “zaraz”, meaning “river bank cliff”.
• The name “Zaraisk” comes from the word “cassock” (swamp): the city, relative to Ryazan, was located behind the swamps, or “beyond the duckweeds”.
• The name comes from the place in the city where, during epidemics of cholera and plague, the dead were buried.
• According to historian M.N. Tikhomirov, the name of the city comes from the word “infection” (impenetrable, reserved forest).
• The name of the city comes from the word “infect” in its Old Russian meaning “to kill, strike to death.” According to legend, in 1237, Eupraxia, the wife of Prince Fyodor Yuryevich, in order to avoid Tatar captivity, threw herself from her tower and thus killed herself, that is, she became “infected.”

The correct answer to the final round question is: Infection(6 letters).

Ravine

(top, summit, reservoir, ravine, ravine, hollow, pothole, ditch, failure). Water falling from the atmosphere, running in the form of streams along an inclined surface, is capable, under certain conditions, of eroding land. This is how all the elongated erosion potholes occurred - most of the river valleys, gullies and ravines, of which the latter represent only the youngest or first stage of the erosion process or, as geologists say, the formation of negative relief forms. Under favorable conditions, that is, with a significant slope of the terrain, with loose soil and ground, in the absence of forests, etc., sometimes the most insignificant reason is enough for the formation of O., for example, a furrow along a slope, a path trampled by cattle, a crack in the soil, etc. The most common reasons for the emergence of O. are the following (according to a report by Mr. Kern): 1) clearing of forests or shrubs growing along the O. and uprooting of stumps; 2) plowing of sod-covered large slopes with an angle of incidence of 20 degrees or more, depending on the soil and geological structure of the walls of the lake; 3) drawing border furrows towards the lake, lowlands and hollows; 4) digging ditches, quarrying stones and, in general, any violation of the integrity of the turf cover on a steep slope; 5) grazing livestock on steep slopes and especially driving them along one path; 6) solar heat and severe frosts, causing cracks in the soil; 7) plowing of the so-called “saucer-shaped basins” in the steppe; 8) formation of railway embankments and excavations; 9) vestments for lowering forests in mountainous areas; 10) landslides and failures that occurred due to geological reasons. Among these factors, the most prominent place, undoubtedly, is occupied by deforestation along the slopes. As an instructive example, we can point to O. in the upper reaches of the Oka, between the village of Verkhnyaya Morozikha and the village of Voronets. According to S.N. Nikitin, all the lakes here have the same geological structure along the entire route, but their fate and development are strictly dependent on the distribution of forest areas. Near the village of Morozikhi, ravines cause terrible destruction on arable land, but in the nearby forest area we see them only overgrown, with completely inactive peaks. But closer to the village of Voronets, vast areas of forest were cleared several years ago, and in the tops of these overgrown and decayed mountains, water holes, powerful destruction and loess cliffs had already begun. Usually, quickly passing through the stage of a ditch and pothole, O. energetically begins to deepen and grow at its top. Sometimes the walls of the O. are made flatter, tinned or overgrown with forest, and the O. freezes and turns into a beam. But more often the lake remains active, creates conditions on its walls for the formation of new oxygen branches, and then, in a relatively short time, the country is covered with a dense and intricate network of water. Areas lined with loose material—the steppe strip—are especially distinguished by the significant erosion of their surface. Russia, Turan, China, some states of North America, Spain, etc.

To judge the ravineness of southern Russia, it is enough to look at the attached piece of a three-verst map of the Poltava province, which can be considered still moderate in ruggedness of the O. (Fig. 2).

There are areas in the south where the area under water occupies 15-20% of the entire area. In the districts of Zadonsky, Nizhnedvitsky, Korotoyaksky and Bogucharsky, the area of ​​inconvenient land is about 120 thousand dessiatinas, of which a significant part should be attributed to the steep slopes of the O. There is reason to think that man found the relief of the southern Russian steppes already at a stage of rest, i.e. . with tinned or afforested beams, and only later plowing of the slopes and clearing of forests brought the country to the sad state in which it is now. And nowadays it is not uncommon to find secondary active water at the bottom of a once tinned beam, up to 15 or more meters deep. There is little information in the literature about the growth rate of O. in the literature. The lake near Horishny Mliny, near the town of Kobelyak, grew its peak, from 1872 to 1888, by 320 feet, i.e., it grew at a rate of about 3 fathoms per year. In the Lebedyansky district of the Tambov province, on the site of a drained pond in 1862, O. (Knyazhoy) was formed, which over the next 6 years lengthened by 70 fathoms and formed a branch 30 fathoms long. 30 years later (in 1892) it grew by another 250 fathoms and deepened by 3 fathoms. Over the past 24 years, water has carried away at least 2,400 cubic meters. fathoms of land, forming a gaping abyss with an area of ​​about 2 acres. Based on all such indications, we can accept the average growth rate of O. equal to about 3 fathoms per year. For the most part, the upper reaches of the O. are a cauldron- or circus-shaped chasm, with completely vertical walls. Vertical columns of earth are separated from them in the spring and after rainstorms, fall into the cauldron, are ground and carried away by water. Further, towards the mouth of the O. it becomes wider, the walls are lower; a lot of landslides, collapses and screes appear; finally, at a known angle of incidence of the slope, the lake freezes, that is, becomes turfed. The looser the surface rocks, the longer, deeper, and steeper the slope. The lakes of our steppe strip can be divided into two large types - the lakes of the southwestern steppe, loess, and the lakes of the eastern steppe, clayey. The former are characterized by their significant size and steep walls, which in the upper reaches of the O. are usually vertical. The latter are wider and have gentler slopes. Here the descent to the lake sometimes begins a mile or more from the riverbed, while in the loess steppe the completely flat terrain almost suddenly ends in some lake. The character of the lake is also reflected in the physiognomy of the steppe: while the eastern part of the steppe strip appears as a whole system of ridges , convexities - the southwestern one seems to be a boundless, smooth plain, corroded by furrows - enemies. The average size of Poltava O. is as follows: length 7.4 versts, width 23.6 fathoms, depth 5.6 fathoms. However, in the same province there are O. 70 versts in length, 140 fathoms in width, 8 or more fathoms in depth. With such a significant length, rivers can cut watersheds, thus connecting different river systems. The connection can occur either directly, by direct growth of the O. up to the neighboring valley, or through the closure of two, going towards each other. Thus, in the Zenkovsky district there are O.-beams belonging to the Psyola system, whose peaks come very close to the right bank of the Vorskla. For example, the watershed Psel - Goltva - Vorskla (Volchek, Bolshaya Krivaya Ruda, etc.) is rich in connections of the second kind, through ties. In this way, there was even a change in the flow of the river, movement of watersheds, etc. Thus, according to Sokolov, the beams in the Alexandria district of the Kherson province (Bogdanovka, Chumyannaya, Chernolesska, etc.) belonged earlier to the Tyasmina River basin and only later were captured by the Ingulets River, as a result which was the movement of the watershed to the north and a change in the flow of water in the direction opposite to the previous one. The importance of oxygen in saving nature is enormous. Generally speaking, the process of ocean formation leads to leveling the surface of the globe by eroding the convex parts and filling the sea depressions with solid material. In particular, on any given piece of land this process leads to extreme furrowing of the surface, and this circumstance is extremely unfavorable for humans. Here are the main consequences of O.'s growth: 1) Soil is washed away and carried into rivers and seas. In this way, every year many thousands of acres of rich black soil are taken away from the southern Russian farmer, which, in turn, clogs the river beds. The frequent shallowing of rivers is mainly due to this circumstance. 2) Rapid drainage of precipitation. Hence the strong water flows in the spring and after rainstorms, the shallow waters of the rivers the rest of the time and the small flow of water into the subsoil horizons. 3) Drainage of the area and lowering the groundwater level. The phenomenon is especially pronounced when the lake has cut through a formation of water-bearing rocks and its bottom rests on waterproof rocks. The drying up of the steppe and agricultural hardships should be attributed, to a large extent, to this factor. 4) An increase in the evaporating surface, in some places by 25-50% of the total area of ​​the earth, also plays a significant role in the drying out of the area. 5) The drift of cultural areas with sand almost always occurs when O. cuts through the thickness of sand, which is blown out of the riverbed. 6) Cutting O. roads is a common and ruinous phenomenon. Between Alatyr and Ardatov, over a distance of 22 versts, in the second half of the fifties there were three bridges across the O., but now there are 42 of them. These are the main consequences of the ravine, forcing one to look at the O. as an enemy, the fight against which is urgent, although voices were heard and in defense of O. (Krasnov, Mertvago).

Literature. Kipriyanov, “Notes on the distribution of ravines in southern Russia” (Journal of the Main Directorate of Communications, 1857); V. Dokuchaev, “O. and their significance” (“Proceedings of the Imperial Free Economic Society”, 1887, vol. III); N. Sumtsov “Ravines” (popular essay, Kharkov, 1894); E. Kern, “Gullies, their consolidation, afforestation and damming” (3rd ed., M., 1897). In addition, many individual chapters and information about O. are scattered in various “Proceedings” of natural history expeditions, geological works, etc.

P. Ototsky.

Strengthening ravines. Oxygens are not formed equally quickly on all soils; for their formation it is necessary, on the one hand, the periodic appearance of masses of water that cannot be absorbed by the soil, and on the other, a certain tendency. soil to erosion, due to the low cohesion of its particles. The strongest influence of periodically flowing waters can be observed on the slopes of mountains, the tops of which are covered with eternal snow, then on the slopes of more or less extensive plateaus (for example, Yayla in the Crimea); in these cases, the destructive power of water is greatly enhanced by the speed of its flow along a more or less steep slope, so that the most cohesive soils are easily eroded. Only the presence of forest weakens the rate of water flow and protects the soil of the slopes from erosion. In flat areas, periodically appearing waters do not acquire such significant speed and such destructive power; in addition, a significant portion of slowly flowing water may be absorbed by the soil. Therefore, erosion is not always observed in the plains: the presence of grass (turf), like the presence of forests on mountain slopes, weakens the rate of water flow and, in addition, increases the cohesion of the top layer of soil, in which the roots of herbaceous plants branch abundantly. The destruction of the grass cover that held the soil together is often sufficient for the destructive power of water to manifest itself and soil erosion to occur. The destruction, or rather weakening, of the grass cover occurs most often under the influence of livestock grazing, which, moreover, tramples the top layer of soil, thereby weakening its cohesion. Also contributes significantly to the formation of gullies plowing soil. Arable land, however, absorbs water much more strongly than unplowed soil, and in a completely flat place it can even stop the flow of periodically appearing water [One of the rare exceptions can be observed in our steppes, where late snow often falls on soil that has already frozen and the resulting when it melts, its water flows over the frozen soil without seeping into it.]; but the cohesion of the soil decreases so much during plowing that the slightest unevenness, an insignificant hollow, is enough for soil erosion to be detected. The more the lake grows, the more the destructive power of water is manifested in it, washing away the slopes and carrying the washed away soil to the mouth of the lake; these outflows (in the Caucasus they are called mudflows) or are deposited in places flooded with water, forming unwanted sediments, or, when entering rivers, they contribute to the formation of shoals in them, making navigation difficult. Therefore, those who continue to expand, or as they are called, long-term O. pose known dangers to underlying areas and their strengthening may be of national interest. O. of small extent, which began to form recently, usually calm down on their own as soon as the influence of the cause that caused their formation is eliminated, i.e., grazing of livestock, plowing of slopes, etc. stops; the slopes of such an O. are overgrown with grass, and sometimes forest, and it becomes a inactive or calm. Plowing of slopes or increased grazing by livestock can again cause erosion of the quiet lake and cause its further growth, which is expressed in the formation of new branches or so-called screwdrivers. Thus, preventive measures in relation to O. are reduced to protecting the grass cover existing on the slopes and along the openings. The fight against active lakes consists of artificially strengthening them, followed by either afforestation of the slopes or damming the lake to form a permanent reservoir. The technique of work carried out to strengthen the mountains was borrowed from the practice of strengthening and afforesting mountain slopes, which developed in France and, later, in Austria. It goes without saying that to strengthen the lake, much weaker structures are sufficient than those that have to be resorted to to weaken the destructive power of mighty mountain streams. The latter are restrained by stone dams, sometimes built with masonry on cement; in the O., barriers are made of wood, most often from brushwood. Dams are built in order to weaken the speed of flowing water and force it to deposit behind the dam those particles of soil and stones that it carries with it. Behind each dam, eventually, a layer of sediment forms and the slope supplied with it turns into a system of terraces that have a very weak fall, at which the flowing water cannot acquire destructive force. The system of such dams, built from fascines, is shown in the attached table.

Strengthening the slope with fascine dams.

To determine the number and nature of dams, it is necessary, first of all, to find out the basin of a given lake, that is, to determine the area from which water flows along its bed. For such a determination, it is best to use a terrain plan expressed in horizontal planes (Fig. 3), on which the watershed lines delimiting the O. basin can easily be indicated.

However, depending on the properties of the soil and the condition of its surface, a larger or smaller part of the pool will absorb the water falling on it, which, therefore, will not flow into the O. For given soil properties, the boundaries of such a safe part of the pool will be determined by a certain maximum angle of inclination of the surface . But an accurate determination of the area of ​​the basin is important when regulating mountain streams, where a large basin with steep slopes requires the construction of capital dams, while barriers built in the lake, despite all their lightness, usually turn out to be abundantly sufficient. These barriers are made of stakes and brushwood, which is either tied into fascines or braided between stakes driven into the ground. In especially dangerous places, such barriers are made double or even triple (Fig. 4), but in the vast majority of cases they are limited to single ones.

A cross-section of a dam made of braided brushwood is shown in Fig. 5, fascine - in Fig. 6.

If you use fresh willow brushwood or fresh willow stakes for such dams, they will easily take root in the soil applied to the dams, produce new shoots, and the result will be a living dam that is particularly durable. Such a living dam is shown in Fig. 7 [In FIG. 5-7 show the dimensions of individual parts of the dams in meters.]. Installation