Part of the river. What is the delta of the river. Gulf in the lower reaches of the river

What a river is, everyone knows. It is a reservoir that originates, as a rule, in the mountains or on the hills and, having traveled a length of tens to hundreds of kilometers, flows into the reservoir, lake or sea. That part of the river that departs from the main channel is called the sleeve. A site with a rapid current, running along the mountain slopes, - the threshold. So what does the river consist of? On which components can it be divided? Let's consider in more detail what we mean by such a simple and familiar word as "the river".

What is a river?

The first fundamental knowledge of living and inanimate nature we get in school in the lessons of the surrounding world. Students get acquainted with such concepts as stream, river, lake, sea, ocean and so on. Naturally, the teacher can not help telling about what parts of the river there are. 2nd grade is too early to remember a lot of terms and concepts. Therefore, children turn to their parents for help. And, I must say, they are at a dead end. Because adults often can not answer such simple questions. So, not everyone will be able to explain what distinguishes the river delta from the riverbed, or how the old people are formed. Or is there another example - what is the river valley? Let's study all these concepts again.

The river is a constant stream of water. In arid regions of the Earth, for example, in Africa and Australia, it may temporarily dry up. The rivers feed on snow, underground, rain and glacier waters. This natural reservoir has centuries developed by its runoff bed. And the relationship between climate and the river is very clear. And it's easy to follow. The flow regime depends on the climate: it is far from the same in different altitude, latitudinal and longitude zones.

The characteristics of the water resource under consideration also directly depend on the terrain and the area in which it is located. The map of the rivers shows that they can pass through the plains, descend along the mountain slopes. They can be found even underground. Plain rivers flow through flat wide areas. Here, erosion of the banks predominates, that is, lateral erosion. The slopes of the reservoir are shallow, the channels tend to be meandering, the current has a weakly pronounced character. Very different characteristics of mountain rivers. The channel is very narrow and stony. The valleys are poorly developed, with steep slopes-banks. Usually such waterways are not deep, but the speed of their flow is enormous.

Also distinguish lake rivers. They can either flow out of the lakes, or make their way through them. Such objects are characterized by a higher drain into the low water. Lake rivers have a long period of high water. As a rule, they are not too long. Several other marsh rivers. They are, of course, less common. They have a more extensive flood, frequent floods are noted due to the characteristic flat terrain, where the channel passes, which is constantly slowly replenished with water from the swamp.

Karst rivers deserve special attention. They feed almost always from underground waters, which fill so-called karst voids. The runoff in these rivers is increased.

The source of the river

The beginning of the river is called the source. This is the place where a constant channel is formed. The source can be different: a stream, a lake, a swamp. The beginning of large rivers are often given by several smaller reservoirs. At this source will be the place of their merger. For example, the beginning of the river Ob is given to the waters of Katun and Biya. Mountain rivers are almost always formed from the confluence of many streams. But the plains begin their journey from the lake. It is worth remembering that the geography of each reservoir is individual. And the source of each river is also unique in its own way.

River valleys

Before disassembling the names of parts of the river, it is necessary to dwell on the term "river valley". If to speak in scientific language, then we are talking about elongated depressions created by watercourses. They have a certain bias towards the current. All the parameters of the river valleys (width, depth and complexity of the structure) completely depend on the degree of power of the watercourse. Values have also the duration of its existence, the nature of the surrounding relief. The stability of rocks and the degree of tectonic activity of the area are taken into account.

All river valleys have a flat bottom and slopes. But, again, their characteristics depend on the terrain of the territory. Mountain rivers are distinguished by steep slopes. They are deeper than the plains. In this case, the valleys are not wide, but narrow. Often, they reveal a stepped bottom. Plain valleys are completely different. They consist of the floodplain and riverbed dug by the old men. The young valleys are characterized by steep slopes, and the older ones have stepped banks. Such slopes are called terraces. The older the river, the more stepped banks are wider and wider.

Young rivers do not have terraces. Even the floodplain is not found everywhere. The bottom of such reservoirs is trough-like, often this is due to the fact that the glacier once passed through this territory. But there are exceptions.

The main parts of the river - the channel and floodplain - are formed in different ways. In rocks that are susceptible to rapid erosion they are much wider than in crystalline soils. Also, the main feature of river valleys is that they always gradually expand to the mouths. Their slopes become more flat, and the terraces are expanded.

There are also river valleys of special practical importance. This is the most convenient place for building settlements. As a rule, on the terraces are cities and towns, and floodplains serve as excellent pasture lands.

The floodplain of the river

If you translate literally, "flood" - this is what floods the water. And this is absolutely correct definition. This is part of the river valley, which is flooded with water during floods and floods. The floodplain has its own unique landscape. Often it is divided into two levels. The lower floodplain is flooded regularly, from year to year. The upper part - only in those years when there is a high water level.

Each flood leaves its imprint on the floodplain of the river. It erodes surface soils, creates rills and forms old people. Every year, sand, pebbles and loam remain on the surface of the earth. This leads to an increase in the floodplain level. At the same time, the process of deepening the channel is underway. Over time, the low floodplain turns into a high, terraces above the floodplain. They have a stepped nature. The floodplain has coastal cliffs a few meters high. Often, it forms gullies and old people.

Plains rivers have broad floodplains. For example, in Ob, the width reaches 30 kilometers, and in some areas and more. Mountain rivers can not boast of floodplains. Such areas are found only in scraps, and they can be found on one side and then on the other.

The importance of floodplain lands is great. Such valuable land is used as pastures and hay meadows. The floodplain of almost any large river in the zone of steppes, forest-steppe or taiga is a stable territory for the development of livestock.

Riverbed

The lower part of the river, or rather the valley, is called the riverbed. It is formed by a continuous water flow. It is constantly moving the runoff and most of the bottom sediments. The riverbed, as a rule, has many branches. It is rarely direct, except at mountain rivers.

The riverbed, as it approaches the mouth, forms a multitude of ducts and sleeves. Especially a lot of them in the delta. The river in the river floodplain is formed during periods of high water, but in the hot summer months it can dry up. The sleeves of the flat rivers have a sinuous relief. They are marked by mobile clusters of fine clastic sediments. At the mountain rivers the ducts are formed extremely rarely, and the sleeves are more straight. Often you can find sections of rapids and various height of waterfalls. They can be cluttered with pebbles and large boulders. Plesy - deep sections of sleeves - alternate with rips. Such transitions are often observed in the lower reaches. The width of the sleeves at the deep rivers, for example, such as the Yenisei, Lena, Volga, Ob, can reach several tens of kilometers.

Thresholds

The course of the river often forms thresholds. Especially often they are found in the channel of mountain rivers. The threshold is a shallow section, covered with pebbles or boulders. It is formed in those places where there are difficult to eroded rocks. There are large flow differences. The thresholds, due to their relief, make navigation impossible and greatly complicate the alloy. Sometimes, because of them, a person is forced to build bypass channels. Often downstream from the rapids are built hydroelectric power stations. At the same time, with the maximum benefit, the river falls and considerable slopes. An example is the Ust-Ilimsk hydropower plant on the Angara River.

What is the delta of the river?

The delta is the lowland of the river. It is almost always characterized by numerous branched ducts and sleeves. Delta is formed exclusively in the lower reaches. It is also important to note that a special mini-ecosystem is formed on this part of the reservoir. Each river has a unique and unique.

Most of the major rivers in Russia have extensive deltas with well-developed alluvial activities. The Volga and Lena are always cited as classic examples. Their deltas are huge and forked into a whole network of sleeves. In addition to them, you can also note the Kuban, Terek and Neva. A distinctive feature of deltas located in the southern regions are developed floodplains. Here there is a riotous variety of vegetation, various mammals, amphibians and reptiles find shelter on the shores. Many species of birds in their forests and thickets near the water nest. But these areas are especially valuable in fishery resources. Noting the question of what a river delta is, one can say with confidence that this is a unique microcosm with its own nature.

Limans

When the river flows into the sea, shallow bays are often formed. They are called estuaries. Such a gulf in the lower reaches of the river is a very unusual and picturesque place. Liman arises from the flooding of flat rivers by the sea. It can be open - then it is called a lip. At the same time the bay does not have to be connected to the sea. There are also closed estuaries, i.e., separated from the sea water by a strip of land - a narrow overflow. As a rule, the water of the estuaries is salty, but not to such an extent as the sea one. True, with a small influx of fresh water, it can become very saline. The bay in the lower reaches of the river is not always formed. Many of them are located on the coast of the Azov Sea. Limans are near the Dniester and Kuban rivers.

The mouth of the river

The place where the river flows into the lake, the reservoir, the sea or another pond is called the mouth. It can be different. For example, on the territory adjacent to the mouth, an estuary, lip or a wide delta can form. But river water can disappear, and there are several reasons for this - a fence for irrigation of agricultural plantations or simply evaporation. In this case, speak of a blind mouth, that is, the river does not flow anywhere. It often happens that at the end of its course the water simply goes into the ground, and the flow disappears. Therefore, it can not be said that each river has a well-defined mouth. For example, the channel of the Okavango River disappears in the swamps in the Kalahari Desert. Thus, the source of the river and the mouth are not necessarily clearly expressed, and it is not always possible to detect them.

River tributaries

The tributary is a watercourse flowing into a larger river. From the latter, it usually differs in smaller volumes of water and length. But, according to research conducted in recent decades, this is not always the case. There are several rivers that violate this statutory law. For example, the Oka falls into the Volga, which is inferior to it by the volume of water. At the same time, Kama also flows into this great water artery, which is also more abundant. But on the Volga, all known exceptions do not end. The Angara is recognized as a tributary of the Yenisei. At the same time, that part of the river that merges with the second object has twice the volume of water. That is, we can say with confidence that the Angara is larger. Typically, the tributary has differences in the direction of the valley, so you can accurately determine what it falls into.

But the rivers do not always merge with each other. Sometimes they fall into lakes or other water bodies. Tributaries are divided into right and left, depending on which side they approach the channel. They are of different order: primary and secondary. Some of them flow directly into the channel of the main drain. These are the primary tributaries. All the rivers that connect with them will be of secondary importance. So, for example, Zhizdra is a primary tributary for the Oka and a secondary one for the Volga.

Sleeve of the river

The hose is also part of the river. This can be a branch or "splitting" the channel. Note that the sleeve must necessarily fall again into the river. Sometimes it happens in a few tens of meters, but more often stretches for several kilometers. The hose is formed as a result of sediment deposition. At the same time, an island is formed in the channel. Sleeves have many local names. On the Volga they are called "caves". On the river Severnaya Dvina they are designated by the word "hollow". On the Don, locals call them old-boned. On the river Danube - "girlo". Sleeves can also be secondary. Then they are usually called ducts. Almost all arms and ducts become old men after a while. As the main channel changes, they disconnect.

Staritsa

The Staritsa is an elongated lake or a section of a river that has been detached from the main channel. Starkey can be found in the floodplain or on the lower terrace. They arise when overlapping sandy or clay chalk hoses, as well as the breakthrough necks meanders. Old men always have a characteristic horseshoe shape. They are connected to the waters of the main channel only at the time of the spill. Most of the time they are separate reservoirs. Often they are called floodplain lakes. The scheme of the part of the river, on which all the old people are marked, can give an idea of how the channel looked before. Over time, this object changes - it overgrows, its shape changes. The old man turns into a swamp, and then completely into a damp meadow. After a while, there is no trace left of her.

Level of rivers

The level of the river is the height of the water surface. This concept is used for almost all natural and man-made reservoirs. Each river has low and high values mentioned. The maximum water level is noted during high water, usually in spring and summer. In the fall floods also occur. The reason for this is prolonged rain showers. In winter, the water level drops to the lowest level. Often the river becomes less full and in summer - during prolonged droughts, when the streams flowing into the channel dry up. The regime of each river is strictly individual. Lowering and increasing the water level always depends on climatic and relief features.