What is a river, everyone knows. This is a body of water that originates, as a rule, in the mountains or on hills and, having traveled a path from tens to hundreds of kilometers in length, flows into a reservoir, lake or sea. The part of the river that departs from the main channel is called the sleeve. A section with a fast current, running along the mountain slopes, is a threshold. So what does the river consist of? What components can be divided into? Let’s take a closer look at what we mean by such a simple and familiar word as “river”.
What is a river?
The first fundamental knowledge about animate and inanimate nature we receive at school at lessons of the world around us. Pupils get acquainted with such concepts as a stream, river, lake, sea, ocean and so on. Naturally, the teacher cannot but tell about what parts of the river are. Grade 2 is too early to remember many terms and concepts. Therefore, children turn to parents for help. And I must say, they are perplexed. Because adults often cannot answer such simple questions. So, not everyone will be able to explain how the river delta differs from the riverbed, or how old women are formed. Or another example - what is a river valley? Let's study all these concepts again.
A river is a constant stream of water. In the arid regions of the Earth, for example, in Africa and Australia, it can temporarily dry out. The rivers feed on snow, underground, rain and glacial waters. This natural body of water has been developed for centuries by its channel. And the relationship of climate and river is very clear. And it's easy to trace. The flow regime depends on the climate: it is far from identical in different altitudinal, latitudinal and longitudinal zones.
The characteristic of the water resource under consideration also directly depends on the terrain and on the area in which it is located. The map of the rivers shows that they can pass through the plains, down the mountain slopes. They can be found even underground. Plain rivers flow over flat wide areas. Coastal erosion prevails here, i.e. lateral erosion. The slopes of the reservoir are gentle, the channels are usually winding, the flow is weakly expressed. Very different characteristics in mountain rivers. Their bed is very narrow and rocky. The valleys are poorly developed, with steep coastal slopes. Typically, such aquatic arteries are not deep, but their flow rate is huge.
Also distinguish lake rivers. They can either flow out of the lakes or pave the way through them. Such objects are characterized by a higher runoff at low water. Lake rivers have a long flood period. As a rule, they are not too long. Somewhat different swamp rivers. They are, of course, less common. They have a more extended flood, frequent floods due to the characteristic flat topography of the area where the channel passes, which is constantly slowly replenished with water from the swamp.
The karst rivers deserve special attention. They feed almost always from groundwater, which fill the so-called karst voids. The runoff at low water for these rivers is increased.
Source of the river
The beginning of the river is called the source. This is the place where a permanent channel forms. The source may be different: a stream, a lake, a swamp. The beginning of large rivers is often given by several smaller reservoirs. In this case, the source will be the place of their merger. For example, the waters of Katun and Biya give the beginning of the Ob River. Mountain rivers almost always form from the confluence of many streams. Well, 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 deciphering the names of the parts of the river, you need to dwell on a term such as "river valley." Speaking in scientific language, we are talking about elongated depressions created by watercourses. They have a certain bias towards the current. All parameters of river valleys (width, depth and complexity of the structure) are completely dependent on the degree of power of the watercourse. The duration of its existence, the nature of the surrounding relief also have values. The stability of rocks and the degree of tectonic activity of the region are taken into account.
All river valleys have a flat bottom and slopes. But, again, their characteristics depend on the topography of the territory. Mountain rivers have steep slopes. They are deeper than the plains. Moreover, their valleys are not wide, but narrow. Often they have a stepped bottom. The plain valleys are completely different. They consist of floodplain and riverbed pitted with old people. Young valleys are characterized by steep slopes, while older ones have stepped banks. Such slopes are called terraces. The older the river, the its stepped banks are larger and wider.
Young rivers have no terraces. Even the floodplain is not found everywhere. The bottom of such reservoirs is trough-like, often due to the fact that a 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 gentle, and the terraces - expanded.
The river valleys have special practical significance. This is the most convenient place for the construction of settlements. As a rule, cities and towns stand on terraces, and floodplains serve as excellent pasture land.
Floodplain
Translated literally, “floodplain” is what floods water. And this is an absolutely correct definition. This is part of the river valley, which during floods and floods is completely flooded with water. The floodplain has its own unique landscape. Often it is divided into two levels. The lower floodplain is poured regularly, from year to year. The upper part - only in those years when there is a high water level.
Each flood leaves its mark on the floodplain of the river. It erodes surface soils, creates gaps and forms old people. Every year, sand, pebbles and loams remain on the surface of the earth. This leads to an increase in floodplain level. At the same time, there is a process of deepening the channel. Over time, the low floodplain becomes high, floodplain terraces form. They have a stepped character. The floodplain has coastal cliffs several meters high. Often on it ravines and elders form.
The plains have wide floodplains . For example, the Ob reaches a width of 30 kilometers, and in some sections more. Mountain rivers cannot boast of floodplain territories. Such sites are found only in fragments, and they can be found either on the one hand or the other.
The value of floodplain lands is great. Such valuable lands are used as pastures and hayfields. The floodplain of almost any large river in the zone of steppes, forest-steppes or taiga is a stable territory for the development of animal husbandry.
Riverbed
The lowest part of the river, or rather the valley, is called a channel. It is formed by a continuous water stream. The runoff and most of the bottom sediments are constantly moving along it. The channel, as a rule, has many branches. It is rarely direct, except in mountain rivers.
The channel, as it approaches the mouth, forms many channels and sleeves. Especially a lot of them in the delta. The channel in the floodplain of the river is formed during floods, but in the hot summer months it can even dry out. The branches of the lowland rivers have a meandering relief. On them, mobile accumulations of fine clastic sediments are noted. In mountain rivers, ducts are formed extremely rarely, and the arms are more straight. Often you can find sections of rapids and various heights of waterfalls. They can be cluttered with pebbles and large boulders. Reach - deep sections of the sleeves - alternate with rifts. Often such transitions are noted in the lower reaches. The width of the branches near full-flowing rivers, for example, such as the Yenisei, Lena, Volga, and Ob, can reach several tens of kilometers.
Thresholds
The course of the river often forms rapids. Especially often they are found in the bed of mountain rivers. A threshold is a shallow area littered with pebbles or boulders. It is formed in those places where hard eroded rocks lie. Large changes in the flow are noted here. The rapids, by virtue of their relief, make shipping impossible and greatly complicate the rafting. Sometimes, because of them, a person is forced to build bypass channels. Often, hydropower plants are erected downstream from the rapids. At the same time, the fall of the river and significant deviations are used with maximum benefit. An example is the Ust-Ilim hydroelectric station on the Angara River.
What is a river delta?
Delta is a lowland of the river. It is almost always characterized by numerous branched ducts and arms. A delta is formed exclusively in the lower reaches. It is also important to note that a special mini-ecosystem is formed in this section of the reservoir. Each river is unique and inimitable.
Most of the large rivers of Russia have extensive deltas with well-developed alluvial activity. The Volga and Lena are always cited as classic examples. Their deltas are huge and branch out into a whole network of sleeves. In addition to them, Kuban, Terek and Neva can also be noted. A distinctive feature of the deltas located in the southern regions are developed floodplains. There is a lush variety of vegetation; various mammals, amphibians and reptiles find refuge on the shores. Many species of birds nest in forests and thickets near the water. But these areas are especially valuable fishery resources. Noting the question about what a river delta is, it is safe to say that this is a unique microcosm with its own nature.
Estuaries
When a river flows into the sea, shallow bays often form. They are called estuaries. Such a bay in the lower reaches of the river is a very unusual and picturesque place. Estuary occurs during flooding of flat rivers by the sea. It can be open - then it is called the lip. Moreover, the bay does not have to be connected to the sea. There are closed estuaries, that is, separated from the sea water by a strip of land - a narrow embankment. As a rule, estuary water is salty, but not to the same extent as sea water. 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 Sea of Azov. The estuaries are near the Dniester and Kuban rivers.
Estuary
The place where a river flows into a lake, reservoir, sea or other body of water is called a mouth. It may be different. For example, in the territory adjacent to the mouth, an estuary, a lip or a wide delta may form. But river water can disappear, and there are several reasons for this - a fence for irrigation of agricultural plantations or just evaporation. In this case, they speak of a blind mouth, that is, the river does not flow anywhere. It often happens that at the end of its path, the water just goes into the ground, and the stream disappears. Therefore, it cannot be said that each river has a well-defined mouth. For example, the bed of the Okavango River disappears in 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 find them.
Tributaries of the river
A tributary is a watercourse that flows into a larger river. It usually differs from the latter in smaller volumes of water and in length. But, as studies conducted in recent decades show, this is not always the case. There are several rivers that violate this established law. For example, the Oka flows into the Volga, which is inferior to it in the volume of water. At the same time, Kama flows into this great water artery, which is also more full-flowing. But on the Volga, all known exceptions do not end there. The Angara is recognized as a tributary of the Yenisei. Moreover, that part of the river that merges with the second object has twice as much water. That is, with confidence we can say that the Angara is larger. As a rule, the inflow has differences in the direction of the valley, so you can accurately determine what it flows into.
But rivers do not always merge with each other. Sometimes they flow into lakes or other bodies of water. Inflows are divided into right and left, depending on which side they approach the channel. They come in different orders: primary and secondary. Some of them flow directly into the main drainage channel. These are primary tributaries. All the rivers that connect with them will be secondary. So, for example, Zhizdra is the primary tributary for the Oka and secondary for the Volga.
River sleeve
The sleeve is also part of the river. This may be a branch or "splitting" of the channel. Note that the sleeve must necessarily flow back into the river. Sometimes this happens after several tens of meters, but more often stretches for several kilometers. The sleeve is formed as a result of sediment deposition. At the same time, an island forms in the channel. Sleeves have many local names. On the Volga they are called “Volozhki”. On the Severnaya Dvina River, they are designated by the word "hollow." In the Don, locals call them the antiquity. On the Danube River - "girlo". Sleeves can be secondary. Then they are usually called ducts. Almost all branches and ducts become elders after some time. As the mainstream changes, they disconnect.
Old woman
Staritsa is an elongated lake or a section of a river that is disconnected from the main channel. Starks can be found in the floodplain or on the lower terrace. They arise when overlapping sand or clay shoals of the arms, as well as when breaking through the necks of meanders. The old women always have a characteristic horseshoe shape. They connect with the waters of the main channel only at the time of the spill. Most of the time they are separate bodies of water. Often they are called floodplain lakes. The scheme of the part of the river on which all the old ladies are marked can give an idea of how the channel looked before. Over time, this object changes - it overgrows, its shape is transformed. The old woman turns into a swamp, and then completely into a damp meadow. After some time, no trace remains of her.
River level
River level is the height of the water surface. This concept is used for almost all natural and artificial reservoirs. Each river has low and high mentioned values. The maximum water level is observed during floods, usually in spring and summer. In the fall, floods also occur. The reason for this is the prolonged rainfall. In winter, the water level drops to the minimum mark. Often the river becomes less full and in the summer - during prolonged droughts, when the streams flowing into the channel dry up. The regime of each river is strictly individual. Lowering and increasing water levels always depend on climatic and relief features.