River and river system. Characteristics of the river and its basin

Rivers are natural large water flows that flow in a river valley (in places where the relief occurs), along a washed out bed (a depression in the valley), towards larger rivers, seas or oceans (towards the mouth). Considering that these flows are replenished due to groundwater And atmospheric precipitation, they directly participate in the water cycle in nature, during which water is constantly redistributed over land and in the atmosphere.

Rivers originate from barely noticeable small springs, groundwater, lakes or swamps located high in the glacial mountains. It is worth noting that the combination of a river and a lake, especially if the reservoir is large, often gives life to the largest river streams, for example, the beginning of the Neva River is located in Lake Ladoga.

The source of the river is formed from a small trickle, to which other small streams join, first forming a stream, then river streams. Some of them, after some time, turn into large rivers (the main river flow moves towards the sea or ocean), while others turn out to be their tributaries.

The more rain falls in the area where the main river flows (this is typical for the equatorial strip), the more tributaries move towards it, forming a river system (the area from which this system collects water is called a basin). But in desert areas, where precipitation is extremely low, the river, no matter how large it is, has almost no tributaries. A striking example of this could be the most long river The Nile, which flows in Africa, is fed mainly by rainfall at the equator.

Therefore, that part of the earth's surface from which water collects first in streams, then in streams and rivers, scientists call a drainage basin.

Thus, the catchment area of the stream is very small and amounts to several square meters, while near the stream the drainage basin expands to several hectares, and near the river it reaches up to square kilometers. The line that separates the watersheds is called a watershed, from where water is directed in two opposite directions.

Since water arteries are distributed very unevenly on the surface of the planet, the answer to the question of where most river flows flow may be surprising: Atlantic Ocean has a greater flow than Pacific Ocean. This is due to the fact that almost along the entire coastline itself big ocean On our planet, mountains stretch from the side of the American continent, stopping large rivers and directing them in the other direction (only 20% of all rivers on Earth reach it, while more than 53% of river flows flow into the North and Atlantic oceans).

Nutrition

If the water streams were not replenished along the way by the waters flowing into them, the river would not reach the mouth. Therefore, in winter, the rivers are fed due to the release of groundwater into the river bed, while the river in the spring is replenished due to melted snow or a glacier, and in the summer in this process Active participation it rains.

It is interesting that there are river streams that are characterized only by rain feeding (the largest river in the world, the Amazon) or glacial (Amu Darya in Central Asia), and there are those that take water from where they can: they are characterized by mixed feeding (almost all rivers of Russia ).

Water in the waterways of our planet comes from only 60% of the land: in dry regions, the amount of precipitation is small and it is almost immediately irretrievably absorbed into the ground, while in cold regions the moisture freezes - and in order to get to the river, it may take frozen water a large amount of time.

Classification

The waterways of our planet are usually divided into flat, mountain, and sometimes underground, swamp, lake and karst.

Mountain rivers flow in narrow valleys through terrain characterized by a large angle of inclination, which is why the flow speed of the river originating in the mountains is high. Their sources are located high in the mountains, and the channel often occupies the entire bottom river valley. True, on the plain they change greatly (first of all, the flow speed decreases) and they acquire all the characteristics of lowland rivers.

But the flow speed of a lowland river is low: the source of the river is located at a low altitude, while the territory through which they flow, moving towards the mouth, has a slight slope. Plain streams are characterized by a wide river valley, in the center of which they have made their way, sloping low slopes, and a winding bed (a striking example: the longest river in the world, the Nile, or the deepest river, the Amazon).

It is worth noting that both mountain and lowland river flows can have thresholds, the presence of which dramatically changes the speed of the river flow.

They are formed due to the fact that the bottom of river valleys usually consists of loose rocks, which are very easily washed away by the current. But there are parts of the river where the valley floor consists of hard rocks (for example, granite or shale), which erode slowly and form ledges in the middle of the river. Passing them, the speed of the water increases, it foams, splashes fly up, whirlpools form, and if the height of the ledge exceeds a meter, waterfalls appear.

Also interesting features have underground rivers, flowing underground in caves. They usually occur in rocks formed from limestone deposits. The longest river in Puerto Princesa, flowing through karst caves, is located in the Philippines, on the island of Palawan, and its length is about eight kilometers.

As for the size of the territory covered by waterways, the classification is as follows:

Small - usually these are flat water streams, the catchment area of which is from 1 to 2 thousand km2, and the length of the rivers is from 10 to 100-200 km;
Medium - these are mainly streams flowing on the plain, the catchment area ranges from 2 to 50 thousand km2, and the length of the rivers ranges from 100 to 500 km;
Large - large river streams, the length of which exceeds 500 km, usually cross several geographical latitudes. These include lowland river systems with a drainage area exceeding 50 thousand km2, and mountain rivers with a drainage area of 30 thousand km2.

The role of water arteries in the life of the planet

Rivers and lakes play an important role in the life of our planet: they not only actively participate in the water cycle in nature, but also have a significant impact on the formation of the relief. For example, they erode rocks and transport them along the coast towards the mouth. According to scientists, the flow of rivers annually transports about 16 billion tons of stones, rocky debris and other materials to the mouth.

The greater the slope of the area where the stream flows, the more destructive its effect on the rocks (this is noticeable when the river in the spring during the melting of snow or in the summer due to heavy rains overflows its banks and floods the entire valley, and sometimes leaves its borders). At the beginning of their journey, all the rivers of the world actively cut into the ground, forming and deepening the valley.

In the middle part of the river and closer to the mouth, where the angle of inclination of the terrain through which the stream flows decreases, the water begins to deposit the rocks it brought, erodes the slopes of the valley and, reducing their base, makes it steeper, and on the river bank, if the bank is flat, depositing sediment forms beaches.

Man and river flows

Man has long learned to use the flowing waterways of the Earth to his advantage: almost all the settlements of ancient civilizations were located on the banks of the river - water in former times was a source of food and contributed to the development of agriculture.

The soil at the mouth of the river was especially good: due to frequent flooding, the land was well irrigated, which contributed to fertility (in our time there is also a high population density here).

All settlements located along the river, throughout the history of human civilization, had an excellent opportunity to develop trade, transporting goods over vast distances, contributing to the prosperity of the city and improving their well-being. At the same time, representatives of different countries often drew borders along the river.

With the development of new technologies, man has learned to use the energy of water flows. The most simple example is a windmill located on the bank of a river, or a hydroelectric power station built along the river, which allows not only to obtain cheap electricity, but also the dam constructed at the same time makes it possible to control the amount of water flow, and also creates reservoirs where water accumulates and is then used as needed.

Rivers are natural water streams flowing in the depression they have created, the bed, and are fed by surface and underground runoff from their territory and basins. A “river basin” usually means an area bounded by a watershed line, the flow from which flows into the main river and its tributaries. Rivers have a source - the place where the river (lake, spring) begins and an estuary - the place where the river flows into another river, lake, sea (mouths can be “blind” or “dry”). The main river and its tributaries form a river system. Between river basins there is a border - a watershed. The set of all watercourses and reservoirs of a territory is called a hydrographic network.

TO the most important characteristics rivers include its water content, the structure of flow by power sources, the type of water regime, the length of the river, the catchment area, the slope and fall of the river, the width and depth of the channel, the cross-sectional area, the speed of water flow, its temperature, chemical composition water, etc.

All rivers are divided into mountain rivers with fast currents, flowing in narrow valleys, and lowland rivers with a characteristic slow flow and wide terraced valleys.

According to the sources of river nutrition and the distribution of their flow by season, 38 types of water regime are distinguished.

Rivers are characterized by a very uneven distribution of flow over time. The main phases of the water regime of rivers are high waters, floods and low water.

The natural mineralization of most rivers is relatively low - usually less than 200 mg/l. Their water would be quite suitable for drinking if it were not contaminated with waste from economic activities.

River- a natural constant water flow flowing in a depression created by it - a channel. In turn, the channel is only part river valley– a linearly elongated depression, along the bottom of which a river flows in accordance with the slope of the bed. In mountain rivers, the bottom of the valley is almost completely occupied by the river bed; in lowland rivers, it is occupied by the bed and floodplain. Channels most often have a meandering shape, but large rivers and rivers in the foothills can branch into branches. Channels of a relatively rectilinear shape are less common.

Every river has source- the place where the river originates, where the river bed acquires a clearly defined outline and a current is observed in it. Rivers can originate from springs, glaciers, or lakes. It is sometimes said that rivers are also formed by the confluence of two other rivers. In fact, a new river toponym, that is, a new name, can arise in this way, while the constituent rivers, no matter what they are called, have typical sources. Example: the rivers Biya and Katun give rise to the Ob. The Amur begins at the confluence of the Shilka and Argun rivers.

Estuary– a place where a river flows into another river, lake or sea. A river may have a “dry mouth”, i.e. it may end at a “blind end”, if in the lower reaches the slopes of the territory through which the river flows are very small, water consumption for evaporation, filtration into the ground or for irrigation is high (Chu Tarim rivers , Murghab, etc.).

Hydrographic network– a set of watercourses and bodies of water on land natural origin(rivers, lakes, swamps) and reservoirs within any territory. River network– a set of rivers located within this territory; it is part of the hydrographic network.

The river network consists of river systems.

River system- the main river with its tributaries. For example, a significant part European Russia takes river system Volga with tributaries. Usually the longest and deepest river is considered the main one. But a number of names of the main rivers were strengthened historically; the main river became the one that people knew earlier and better. For example, the Volga is inferior in length to both the Oka and Kama from its source to its confluence with them; The Missouri is longer and deeper main river Mississippi. According to one classification, the tributaries of the main river are called tributaries of the first order, their tributaries are called tributaries of the second order, etc. According to another classification (by the American hydrologist Horton), a river of the first order (elementary river) is considered a river without tributaries, rivers of the second order are formed at the confluence of two rivers of the first order, rivers of the third order - at the confluence of two rivers of the second order, etc. Thus, the higher the order number of the river, the more complex the river system is. There are other approaches to classifying rivers.

River basin- part of the earth's surface that includes a given river system. Most large swimming pool the Amazon has 7.2 million km 2. drainage basin- the area of land from which a river system collects its waters. It may be smaller than a river basin if there are drainage areas within the latter (for example, as in the Irtysh basin).

Watershed– a line on the earth’s surface dividing the runoff of precipitation along two oppositely directed slopes. The entire globe can be divided into two main slopes along which water flows from the continents: 1) into the Atlantic and Northern Arctic Oceans; 2) in Quiet and Indian Oceans. Between these two slopes passes World watershed, or the Main Divide of the Earth. The watersheds between the peripheral areas and the internal drainage areas are called internal watersheds. Watersheds between oceans and seas separate areas of land, the flow from which is directed to different oceans or seas. River watersheds are the dividing lines of river systems. Watersheds are better defined in the mountains than on the plains.

Very rarely on accumulative plains it is impossible to draw watersheds at all, since the mass of water from one river is divided into two parts, heading to different river systems. This phenomenon of bifurcation of the flow is called river bifurcation. A striking example bifurcations - the bifurcation of the Orinoco River in the upper reaches: one of them. which retains the name Orinoco, flows into the Atlantic Ocean, the other, Casiquiare, flows into the Rio Negro River, a tributary of the Amazon. There are bifurcations of rivers flowing through the Primorsky lowlands of northeast Russia between the mouths of the Indigirka and Kolyma. Unique case bifurcation is demonstrated by the Onega in the lower reaches, dividing into two branches huge island composed of bedrock. The branches diverge over a distance of up to 20 km and converge again near the mouth.

Each river has certain morphometric characteristics.

River length– the length of the river bed from source to mouth.

River meandering is determined by the coefficient of tortuosity of the river bed (K) - the ratio of the length of the river along the bed ( l) to the length of the river along the valley bottom (L). K= l/L. The tortuosity coefficient is usually calculated for individual river sections.

Density of the river network (D) is the ratio of the total length of all rivers of the river system to the river basin (F): D=ΣL/F km/km 2 .

Longitudinal profile The river is characterized by the longitudinal profile of the bed of the channel (it always looks like a wavy line) and the water surface (a smoother line). The fall of a river is the height difference between the source and the mouth of a river or the difference in heights of two points on the water surface along the length of the river ( h m).

River slope– the ratio of the magnitude of the river fall to the length of the river ( l) or to the length of a certain section of the river ( i=h/l). The slope of a river is a dimensionless quantity. Its values are very small, especially on lowland rivers. Thus, the slope of the Oka in the middle reaches is only 0.00009, so the slope is often replaced by a kilometer drop - a value physically identical to the slope, but expressed in m/km. The kilometric fall of the Oka is 0.09 m/km.

The longitudinal profiles of rivers are different depending on the properties of the rocks composing their beds and slopes. In most lowland rivers flowing through loose sediments, it has the appearance of a concave curve, flattening towards the mouth. In mountain rivers, the longitudinal profile of the channel is usually stepped, and the steps are associated with unequal erosion of the rocks composing the channel. In places where rocks are hard to erode, profile breaks are observed in the form of thresholds or steep ledges, which are associated with rapids or waterfalls, respectively. There are also rapids on lowland rivers, for example the famous Dnieper rapids, formed when the Dnieper crossed the crystalline ledges of the Ukrainian shield. The length of rivers flowing from lakes is typical of convex or convex-concave longitudinal profiles.

Water section of the river is the cross section of a riverbed filled with water.

Live cross section of the river– cross-sectional area of the flow. That part of the water cross-sectional area where there is practically no flow is called dead space.

The elements of the river’s water section are: its square (ω); channel width(IN); maximum depth (h max), average depth, which is calculated by the formula h medium = ω/V; wetted perimeter(P) – the length of the underwater contour of the river from the edge of one bank to the edge of the other bank; hydraulic radius(R) – ratio of the water cross-sectional area to the wetted perimeter: R= ω/P. The hydraulic radius characterizes the shape of the channel in cross section: for lowland rivers it is almost equal to the average depth. The width of the river and maximum depth are determined by direct measurements. Based on slopes, flow velocities and the general hydrological regime in rivers, three flow sections can be distinguished: upper, middle and lower.

The upper reaches of many rivers are mountainous, and even among lowland rivers they are most often located on hills. There are high current speeds here, a rocky bottom, rapids, rapids, and sometimes waterfalls are common, low temperature water. Mountain rivers have a similar character almost throughout their entire length, excluding where they cross intermountain depressions. In sections of the middle reaches of lowland rivers, flow speeds are lower; the bed is composed of sand, gravel, and pebbles. In the lower reaches of the river, they are characterized by low flow speeds, long floods, small sediments, and low banks.

Literature.

Lyubushkina S.G. General Geography: Textbook. a manual for university students studying specialties. "Geography" / S.G. Lyubushkina, K.V. Pashkang, A.V. Chernov; Ed. A.V. Chernova. - M.: Education, 2004. - 288 p.

Water consumptionQ , m/s – the amount of water passing through the cross section of the river in 1 second. Water consumption equal to the product the area of the river's water section by the average flow speed for this section.

Drain volumeV , m or km - this is the amount of water carried by a river through its cross section over a longer period of time (day, month, year).

Where Q– average water consumption for the considered period of time;

t– number of seconds in this interval (for a year t = 31.54·10 With).

To compare the magnitude of river runoff with precipitation or evaporation, runoff is characterized by the height of the water layer. Drain layer, mm is the layer that is obtained if the volume of runoff is distributed evenly over the entire area of the river basin:
.

To compare the conditions for runoff formation in different basins, the amount of water flow related to the area of the basin is often used, i.e. the amount of water flowing from each square kilometer is drain module
, l/s∙km .

The ratio of the runoff layer to the layer of precipitation that fell on the basin area, causing the occurrence of a given runoff value, is called runoff coefficient. It shows what part of the precipitation is spent on the formation of runoff:
.

8.3 Nutrition, water regime of rivers, water balance of the river basin

For rivers, it is necessary to distinguish between: the feeding process, the water flow regime and the process of formation of the channel and valley.

Rivers are fed by rain, snow, glaciers and groundwater.

Rain power predominates in the warm zone and in temperate zones with monsoon climate. The proportion of runoff rainfall increases when it falls on moist soil.

Snow nutrition predominates in cold and temperate zones. The flow of snow water is facilitated by the increased intensity of snowmelt, winter freezing of the soil, and especially the presence of an ice crust on the soil.

Glacial feeding occurs as a result of melting glaciers. The main factors are the catchment area occupied by glaciers and air temperature.

Underground nutrition– the flow of groundwater and interstratal water into the river (the flow of soil water and perched water into the river is conventionally referred to as surface recharge). Depends on geological structure and the distribution of permeable soils, fractured rocks, and forest cover in the basin.

Surface runoff, which is very uneven over time, usually significantly prevails over slow underground runoff. The periods of maximum surface runoff are always confined to certain times of the year. The rapid entry of huge masses of water into the river during periods of maximum surface flow causes a sharp increase in flow rates and a corresponding increase in water levels.

For most lowland rivers of the Russian Federation, the spring flood flow is more than 50% of the total annual flow.

The feeding of rivers by groundwater is most stable and uniform throughout the year. Almost all rivers have underground feeding to one degree or another; for example, near the Volga it is about 30%. On some small rivers, underground nutrition reaches 60%.

Depending on food conditions in river mode they are isolated: high water, floods and low water.

High water– a phase of the river’s water regime, which repeats annually under given climatic conditions in the same season, characterized by the highest water content, a high and long-term rise in water level. Flood is caused on lowland rivers by snowmelt (spring flood), on high mountain rivers by melting snow and glaciers (summer flood), in monsoon and tropical zones by the fall of summer, prolonged rains.

Flood- a phase of the river’s water regime, which can be repeated many times in different seasons of the year, characterized by an intense, usually short-term, increase in flow rates and water levels and is caused by rain or snowmelt during thaws. A flood (flood) of outstanding magnitude and rare in frequency, which can cause casualties and destruction, is called catastrophic flood.

In engineering practice the term flood often replaced by the word flood

Low water- a phase of the water regime of a river, repeating annually in the same seasons, characterized by low water content, long-term low levels and resulting from a decrease in river nutrition. The summer (summer-autumn) low water period includes the period from the end of the flood to the autumn floods, and in their absence - until the beginning of the winter period, that is, before the occurrence of ice phenomena on the river. Summer low water can be stable, long-lasting, as well as intermittent and unstable (periodically disturbed by rain).

Winter low water usually coincides with the freeze-up period. Water flows from the beginning of freezing of rivers gradually decrease, reaching a minimum before opening; this is due to the depletion of underground (ground) water reserves.

The alternation of low-water and high-water flow periods on rivers is an objective and explicable property of rivers, which ultimately has a significant impact on the operation of road culverts and bridge crossings.

Are common patterns of runoff changes by territory can be traced using the example of runoff distribution in the European part former USSR. At latitudes 60-65 there is a “climatic runoff ridge” with a value of 350-400 mm. Hence the decrease in runoff to the north to 300-350 mm due to a decrease in precipitation with a slower decrease in evaporation. In the north of the Kola Peninsula, an increase in runoff is influenced by the relatively warm Barents Sea. A decrease in runoff to the south to 50-100 mm in the steppe zone, to 20 mm on the coast of the Azov Sea and 5 mm in the Caspian lowland, associated with a decrease in precipitation and an increase in evaporation. There is a slight increase in runoff at higher elevations (Valdai, Donetsk ridges, etc.) and a significant increase in the mountains - in the Crimea from 20 to 150 mm, in the Caucasus up to 2000-3000 mm.

River classification according to water regime.

Rivers with spring floods, types:

Kazakhstan - characterized by a very high flood wave and low (until complete drying out) flow during the rest of the year. Runoff is provided almost exclusively by winter precipitation, the rapid melting of which causes high but short-lived floods;

Eastern European - characterized by high spring floods, summer low water, interrupted occasionally by showers, low winter low water and increased autumn runoff. Some rivers of this type have two peaks: in spring and autumn;

West Siberian - has a small, extended flood, increased summer-autumn runoff and low winter low water. The presence of lakes, extensive floodplains in the basins of rivers of this type has a regulating effect on the flow. A long winter predetermines low winter runoff;

East Siberian - characterized by high floods, systematic summer-autumn floods and very low winter runoff. This type of river is associated with heavy rainfall in summer and autumn and limited underground recharge;

Altai - characterized by low, extended, ridge-shaped floods, increased summer-autumn and low winter runoff. The nature of the flood of rivers of this type is determined by the characteristics of snow melting in the mountains. Rain floods are superimposed on snow floods. Steady winter flow is due to groundwater reserves.

R eki with high water warm part of the year, types: Far Eastern, Tien Shan.

R eki with flood regime, types: Black Sea, Crimean, North Caucasian.

Natural water balance of the river basin:

Where x– precipitation on the surface of the pool;

z– total evaporation from its surface;

y– river flow;

- influx of groundwater fed outside the given basin;

- outflow of groundwater formed in a given basin beyond its boundaries not as part of river flow;

- changes in water reserves in the basin, contained in underground aquifers, in soil, in reservoirs and channel networks, in snow cover and glaciers.

On average for a long-term period for the year as a whole
, quantities And are significant, as a rule, only for a part of small rivers, so the water balance equation can be written in a simple form:

Today, no one can say for sure how many rivers there are in the world. After all, everything also depends on what can be considered a river and what can be considered a stream. So, for example, if you add up the length of all the rivers in Russia, you get more than 8 million kilometers. Their total number, if you count large and small, is close to 2.5 million. There are no more than 50 largest rivers on the entire globe, and their total length is about 200,000 km. But what does the source and mouth of the river consist of?

Geographical significance of the river

The river is a stream fresh water, which moves in a fixed channel and is replenished mainly due to precipitation. Before you understand the characteristics of freshwater streams, you need to remember a few key terms:

A channel is a depression along which the flow of water from a river follows. It is usually fixed, sinuous in shape with alternating shallow and deep places. Due to geographical changes or other factors, it may change, leaving behind holes and depressions. So, for example, in India there is the Kosi River, which makes its way almost every year. new way, washing away everything that comes in its way.

The source is the beginning of the river. It could be a spring, a melting glacier, any other body of water, or the confluence of two water streams.
The mouth is the place where a river ends, whether it flows into the sea, ocean or other water stream.
A river system is not only the river itself, but also its tributaries.
The river basin is certain territory, from which all the water is collected. All basins are separated by watersheds, and their role is played by hills.

Main parameters of river characteristics

The main characteristics of rivers are their size, flow speed, flow, fall and type of food.

The fall is the difference between the heights of the source and the mouth. The higher the fall, the greater the speed of flow in the river.

Current speed is measured in m/sec. It will not be the same everywhere; the areas have different terrain and the slope of the riverbed is different.

Water flow shows how many cubic meters passed in 1 second through the cross section of the riverbed.

The river is fed in several ways: by rainwater, after melting ice, from underground springs and glaciers. Rivers located in the tropics are fed by rain. Rivers in temperate zones and those located in the northern hemisphere are fed by snow, while mountain rivers are fed by glaciers. There are several main rivers:

Equatorial - only with rain all year round.
Subequatorial - the river is fed by rain, but it is uneven and seasonal.
Subtropical - rain with a rise in river level winter period and shallowing in summer.
Subarctic is snow feeding, which ensures a rise in water levels in summer and a sharp shallowing in winter, when most of the rivers freeze over.
Ozerny - the river is fully nourished all year round and does not depend in any way on other types of nutrition.
Mountain - in high mountains At night, the rivers become shallow, and during the day they are replenished due to the melting of glaciers and snow.

You can also very often hear about the river regime. But not everyone knows what a river regime is. What does it depend on? The answer is very simple, the river regime is the course of long-term, seasonal and daily changes in the river flow in the channel. Changes can happen very quickly, it all depends on where and under what conditions the river flows.

Rivers flow through the plains, flow down from the mountains, and during their entire life they can change their path several thousand times, become shallower or, conversely, become more full-flowing.

Features of river flow

And the mouth of the river is already known, but what are the features of the water flow in each of them? After all, it is known that there are rivers with standing water and a quiet flow, and there are those where the water flows at such a speed that it can demolish any, even the largest, obstacle in its path.

The nature of the flow and speed of the river depend on the topography, slope and fall of the water. On the plains, river flows are wide, calm, and their fall slope is small. Such rivers include the Volga, Danube, Dnieper, Neman. But there are also those that flow among mountainous hills. They are distinguished by turbulent and strong streams; on their way there are many rapids and sometimes high waterfalls. Such rivers have a huge fall, which means that their flow pattern is completely different. Such streams include the Terek, Rioni, Tigris and Yangtze.

The full flow, regime, and sometimes nutrition of rivers depend on the climate. In humid conditions, rivers remain full at any time of the year, but in dry climates they very often dry out and are fed only by precipitation, and there is not very much of it in a year.

Mountain rivers are cold because they are fed by melting glaciers located on the peaks. But if you walk along the entire riverbed, then at the very end the water can be very warm, since during its journey it heats up under the scorching rays of the sun.

What is a mountain and lowland river?

We have already managed to figure out what a river regime is, but what type of rivers are there? After all, they can simply run among the plains or descend from high mountains.

Lowland rivers are water streams passing through flat terrain with small slopes and flow rates. Such rivers flow in developed valleys with a winding bed, where reaches and rifts alternate.

Mountain rivers originate in the mountains or foothills. They have steep slopes and rocky beds, cluttered with rock fragments. Such rivers are characterized by large slopes and flow speeds, and shallow depths. Often along the path of these rivers there are waterfalls and rapids, and erosion processes also predominate.

There is also mountain-plain rivers, which begin far in the mountains, then gradually turn into a quiet lowland river.

5 largest rivers in the world

Every person knows the name of the largest rivers in the world. List of the 5 largest and deep rivers The world is led by the Amazon, which is considered the heart of South America. More recently, it was considered 2nd on the list of the largest after the Nile. But after scientists accepted the small source of the Ucayali as the true beginning of the river, it began to be considered the longest. Its length is more than 7 thousand km.

In second place was African river Nile. She is considered sacred river, since only thanks to it can people living in the harsh and very dry climate of Africa survive. During the rainy season, the river floods, allowing the population of Africa to engage in agriculture, rice is grown on its banks. The length of the second largest river in the world is just over 6800 km, and the river basin has an area of more than 3 million square meters. km.

The Yangtze is another large river in the world, which is considered the main deep-water stream of Eurasia. This river can be considered a mountain-plain river, since it originates in the Tibetan Plateau, then passes through the Sino-Tibetan Mountains and then flows into the Sichuan Basin. The length of this very deep river is about 6.3 thousand km, and the basin area is about 1.8 million square meters. km.

The Yellow River, or Yellow River, is another major river in the world, with its source in the mountains of Tibet. Its length is about 5 thousand km, and the basin area is 700 thousand square meters. km.

The names of rivers located in Russia can be found on the map. Among them there is one that is included in the list of the 5 largest - this is the Ob. Its length is a little more than 5,400 km, and the basin area is almost the same as that of the Nile - 3 million square meters. km. This water flow originates in Russia, and then passes through Kazakhstan and ends its path in China.

The world's major rivers have great importance for industrial and economic development states in whose territory they flow. Rivers give life-giving moisture to people. In addition, there are a lot of fish in the rivers, which feed not only animals, but also humans.

List of the smallest rivers in the world

But there are not only large rivers on the planet. There are also the smallest ones, which have their own meaning for the people living on its banks. The smallest rivers:

Reprua - this river flows in Abkhazia, and its length is only 18 meters. In addition, it is considered the coldest river on the Black Sea coast.
Kovasselva - this water stream is located on the Norwegian island of Hitra, and its length is no more than 20 meters.

Amazing rivers of the world

The characteristics of rivers are not only information about whether they are large or small in size. There are also unusual and amazing water streams on the planet that attract attention with their originality.

Caño Cristales is the most colorful river located in Colombia. Most often, locals call it the river of five colors. The river acquires such a bright and unusual variety of colors thanks to the algae living in its water. If you look at the water in it, you might think that a rainbow fell into the water.

The Citarum is the dirtiest river on the planet. It is located in Indonesia, and is dirty because more than 5 million people live in its basin. People dump all their waste into its waters. If you look at the river from afar, you won’t even immediately understand what it is; you get the feeling that you’re looking at a landfill.

Congo is the most deep river on the planet. It flows in Central Africa, in some places its depth reaches 230 meters, and perhaps even more.

El Rio Vinegre is the most acidic river. It flows past the Purace volcano in Colombia. Its water contains more than 11 parts of sulfuric acid and 9 parts of hydrochloric acid. There can be no living creatures in this river.

Life in rivers: plants

The characteristics of rivers are not only nutrition, length and other parameters, but also animals and plants. After all, every water stream, be it the largest or smallest, has its own life. In every quick or quiet river Many plants have found their home that adapt to life in a particular stream, with its flow characteristics, water temperature and other parameters.

River plants can be divided into 5 main groups:

Plants found in water and on land. They begin their growth at the bottom of the river, and their upper part rises above the water. These include reed, reed, horsetail, cattail and arrowhead.
Plants whose roots are attached to the bottom and whose leaves float on the surface of the water. Such plants are floating pondweed.
Plants with roots at the bottom, whose leaves remain in the water, are urut and common pondweed.
Plants are floating and have no roots at the bottom. One such plant is duckweed.
Plants that live in the middle layer of water are hornwort, filamentous algae and elodea.

River life: fauna

Characteristics of rivers are also animals that cannot exist anywhere except in water. Not only a large number of fish species live in rivers, but also other living organisms:

Plankton are living organisms that live in the water column; they seem to float in a body of water and surrender to the power of the current. Plankton is the main food for many fish.
Benthos. This group includes bottom organisms.
Nekton are actively moving animals that can overcome currents. Today, there are more than 20 thousand species of nekton, these include fish, squid, cetaceans, pinnipeds, turtles and others.
Neuston - animal and plant organisms that live on the surface of water bordering the atmosphere.
Plaiston is animal and plant organisms that are semi-submerged in water, i.e., capable of living simultaneously in both aquatic and air environments.
Epineuston includes organisms that live on the surface film.
Hyponeuston - organisms associated with the surface film, but living underneath it.
Periphyton are organisms that live on the surface of objects submerged in water.

Mammals also live in the rivers: beavers, otters, muskrats, and reptiles: turtles, snakes, crocodiles.

How are rivers used?

Even in ancient times, people believed that water is life. They often built houses on the banks of rivers and reservoirs to make it easier for them to carry out everyday life. Using the river helps not only to do household chores, but also to run your household. Water from rivers is used for drinking, having been purified beforehand, used to prepare food for themselves and animals, and used for watering plants.

Today, water from rivers is purified at special stations and supplied through pipes to homes in large cities. Rivers are also often used for timber rafting, as a way to travel over long distances. They swim and fish in the rivers. Rivers are also very beautiful landscapes, because it’s nice to sit on the banks and enjoy the fresh moist air, admiring the surroundings.

How much water is needed for industrial enterprises that also build closer to rivers?! Thanks to this proximity, any enterprise will be able to draw water from the reservoir. In distant countries - Africa or South America- where the climate is very dry and the rivers often dry up, the main source of drinking for wild animals is these rivers, even if they are dry in some places. But during the rainy season they become full again.

Without rivers, our planet would not be as beautiful and real. They, like water sleeves, weave around the globe and give life-giving moisture, but the task of humanity is to make every effort to preserve their purity and beauty.

A river is a natural permanent water stream (watercourse) of significant size with a natural flow along the channel (the natural depression it has created) from the source down to the mouth and fed by surface and underground runoff from its basin.

The rivers are integral part hydrological cycle. Water in the river is usually collected from surface runoff resulting from precipitation from a certain area, limited by the watershed (river basin), as well as from other sources, such as groundwater reserves, moisture stored in natural ice (from the melting of glaciers) and snow cover.

In places of natural or artificial obstacles to the flow of a river, reservoirs (flowing lakes or artificial seas) appear. Limnology (Greek λίμνε - lake, λόγος - study) or lake science is a branch of hydrology, the science of the physical, chemical and biological aspects of lakes and other fresh water bodies, including reservoirs. In turn, rivers are the subject of one of the largest sections of land hydrology - river hydrology or potamology (from ancient Greek ποταμός - river, λόγος - study - literally the science of rivers), which studies the structure of river networks, river flow, morphometry of rivers swimming pools and so on. As a rule, rivers make their way and flow through zones of least stress and resistance - along tectonic faults.

For a long time, the energy of fast rivers and waterfalls has been widely used in human economic activity as a source of renewable energy for the operation of water mills and turbines of hydroelectric power stations.

General information

In each river, a distinction is made between its place of origin - the source and the place (section) where it flows into the sea, lake or confluence with another river - the mouth.

Rivers that directly flow into oceans, seas, lakes or are lost in sands and swamps are called main; flowing into main rivers - tributaries.

The main river with all its tributaries forms a river system characterized by density.

The land surface from which a river system collects its waters is called a catchment area, or drainage area. Drainage area including upper layers earth's crust, which includes a given river system and is separated from other river systems by watersheds, is called a river basin.

Rivers usually flow in elongated low forms of relief - valleys, the lowest part of which is called a channel, and the part of the valley bottom flooded with high river waters is called a floodplain, or floodplain terrace.

The channels alternate between deeper places - reaches and shallow areas - rifts. Line greatest depths the channel is called thalweg, close to which the shipping channel or fairway usually passes; line highest speeds flow is called a core.

The boundary of a river's watercourse is the bank; depending on its location along the stream relative to the center line of the watercourse's bed, the right and left banks of the watercourse are distinguished.

The difference in height between the source and the mouth of a river is called the fall of the river; The ratio of the fall of a river or its individual sections to their length is called the slope of the river (section) and is expressed as a percentage (%) or in ppm (‰).

On the surface globe The rivers are distributed extremely unevenly. On each continent, it is possible to outline the main watersheds - the boundaries of the areas of runoff entering various oceans. The main watershed of the Earth divides the surface of the continents into 2 main basins: the Atlantic-Arctic (the flow from the area of which flows into the Atlantic and Arctic oceans) and the Pacific (the flow into the Pacific and Indian oceans). The volume of runoff from the area of the first of these basins is significantly greater than from the area of the second.

The density of the river network and the direction of flow depend on the complex of modern natural conditions, but often, to one degree or another, retain the features of previous geological eras. The river network reaches its greatest density in equatorial belt where they flow greatest rivers world - Amazon, Congo; in tropical and temperate zones it can also be high, especially in mountainous areas (Alps, Caucasus, Rocky Mountains, etc.). Occasional in desert areas flowing rivers, which occasionally turn into powerful streams during snowmelt or intense rainfall (rivers of lowland Kazakhstan, oueds of the Sahara, Creek (a drying up river) and Australia, and others).

Classification

Classification of rivers by size

Large rivers are lowland rivers with a basin area of more than 50,000 km2, as well as predominantly mountain rivers with a drainage area of more than 30,000 km2. As a rule, their basins are located in several geographical zones, and the hydrological regime is not typical for each river geographical area separately.
Middle rivers are lowland rivers, the basins of which are located in the same hydrographic zone, having an area from 2000 to 50,000 km2, the hydrological regime of which is characteristic of rivers in this zone.
Small rivers are rivers whose basins are located in the same hydrographic zone, have an area of no more than 2000 km2 and whose hydrological regime, under the influence of local factors, may not be typical for rivers in this zone.

Topographic classification

Depending on the topography of the area within which the rivers flow, they are divided into mountainous and flat. Many rivers alternate between mountainous and flat areas.

Mountain rivers, as a rule, are distinguished by large slopes, rapid currents, and flow in narrow valleys; erosion processes predominate.
Lowland rivers are characterized by the presence of channel meanders, or meanders, formed as a result of channel processes. On lowland rivers there are alternating areas of channel erosion and accumulation of sediment on it, as a result of which muddy bars and riffles are formed, and deltas are formed at the mouths. Sometimes branches that branch off from a river merge with another river.

Hydrobiological classification

Classification according to the possibility of water sports

According to the International River Difficulty Scale, there are six levels of difficulty.

Classification by tributary network configuration

There are 12 classes of rivers based on the nature of the network of tributaries, determined by the Strahler Number. The headwaters of the rivers according to this system belong to the first class, and the Amazon River to the twelfth.

Use of rivers

Since ancient times, rivers have been used as a source of fresh water, for obtaining food (fishing), for transport purposes, as a protective measure, to delimit territories, as a source of inexhaustible (renewable) energy (rotation of machines (for example, a water mill) or hydroelectric turbines), for bathing, irrigation of agricultural land and as a means of disposing of waste.

Rivers have been used for navigation purposes for thousands of years. The earliest evidence of river navigation dates back to the Indus Valley Civilization, which existed in the northwest of modern Pakistan around 3300 BC. The use of river navigation in human economic activity provides cheap (water) transport, and is still widely used in the most large rivers world, such as the Amazon, Indus, Ganges, Nile and Mississippi (river). The amount of harmful emissions produced by river boats around the world is not clearly regulated or regulated, which contributes to the constant release into the Earth's atmosphere large quantity greenhouse gases, as well as an increase in the incidence of malignant neoplasms among the local population as a result of the constant inhalation of harmful particles emitted into the air by water transport.

Rivers play an important role in determining political boundaries and protecting the country from the invasion of external enemies. For example, the Danube was part of the ancient border of the Roman Empire, and today the river forms much of the border between Bulgaria and Romania. The Mississippi in North America and the Rhine in Europe are the main borders dividing the east and west of countries located on their respective continents. In southern Africa, the Orange and Limpopo rivers form the boundaries between provinces and countries along their routes.

Flood

A flood (or flood) is part of the natural cycle of a river - one of the phases of the river’s water regime, repeating annually in the same season of the year - a relatively long and significant increase in the river’s water content, causing its level to rise. Usually accompanied by the release of water from the low-water channel and flooding of the floodplain.

Flood is a phase of the water regime of a river - a relatively short-term and non-periodic rise in the water level in the river, caused by increased melting of snow, glaciers or an abundance of rain. Unlike a flood, a flood does not recur periodically and can occur at any time of the year. Significant flooding may cause flooding. As the flood moves along the river, a flood wave is formed.

Flood - flooding of an area as a result of rising water levels in rivers, lakes, seas due to rain, rapid snow melting, wind surge of water to the coast and other reasons, which damages people's health and even leads to their death, and also causes material damage . Wind surges of water in sea estuaries and on windy areas of the coast of seas, large lakes, and reservoirs. Possible at any time of the year. They are characterized by a lack of periodicity and a significant rise in water levels.

Much of the process of erosion of river beds and deposition of eroded rocks on the corresponding floodplains occurs during floods. In many developed areas of the world economic activity humans have changed the shape of river beds, influencing the magnitude (intensity) and frequency of floods. Examples of human impacts on the natural state of rivers include the construction (creation) of dams, straightening of riverbeds (construction of canals), and drainage of natural wetlands. In most cases, human mismanagement in floodplains leads to a sharp increase in the risk of floods:

artificially straightening a river bed allows water to flow faster downstream, increasing the risk of flooding in areas downstream;
changing the nature of the river floodplain (straightening) removes natural flood control reservoirs, thereby increasing the risk of floods in the lower reaches of rivers;
creating an artificial embankment or dam can only protect the area downstream of the river (behind the dam), and not those areas that are located upstream;
The presence of a dam, as well as straightening and strengthening of banks (for example, the creation of embankments, etc.) can also increase the risk of flooding in areas located upstream of the river. As a result, there is a difficulty in outflow and an increase in pressure exerted on the downward flow, associated with an obstacle to the normal outflow of water due to the narrowness of the channel enclosed between the reinforced banks.

underground river

Most, but not all rivers flow on the surface of the Earth. Underground rivers flow underground in caves. Rivers of this kind are often found in regions with limestone (karst) deposits in geological formations. In addition, there are caves formed in the body of glaciers by melt water. Such caves are found on many glaciers. Melted glacial waters are absorbed by the body of the glacier along large cracks or at the intersection of cracks, forming passages that are sometimes passable for humans. The length of such caves can be several hundred meters, depth - up to 100 m or more. In 1993, a giant glacial well “Isortog” with a depth of 173 m was discovered and explored in Greenland; the influx of water into it in summer was 30 m3 or more. Due to the presence of a “roof” formed from geological rocks that are impermeable to water (or ice) and high pressure, directed towards the overlying massifs of the glacier, a so-called topographic gradient is created - such streams can even flow uphill. Another type of glacial caves are caves formed in a glacier at the point of release of intraglacial and subglacial waters at the edge of the glaciers. Meltwater in such caves can flow both along the glacier bed and over glacial ice.

Water is usually found in many caves, and karst caves owe their origin to it. In caves you can find condensation films, drops, streams and rivers, lakes and waterfalls. Siphons in caves significantly complicate passage and require special equipment and special training. Underwater caves are often found. In the entrance areas of caves, water is often present in a frozen state, in the form of ice deposits, often very significant and perennial.

Puerto Princesa Underground River is an underground river near the Philippine city of Puerto Princesa, on the island of Palawan (Philippines). This river, about 8 km long, flows underground, in a cave, towards the South China Sea. Created in the area where it is located national park underground river of the city of Puerto Princesa (Puerto Princesa Subterranean River National Park) - a nature reserve located 50 km from the city. The park is located in the St. Paul Mountain Range in the northern part of the island and is bounded by St. Paul Bay and the Babuyan River. A similar river is known on the Yucatan Peninsula in Mexico, but this one is recognized as the largest. Both underground rivers owe their origin to karst terrain. The water in these rivers changed direction, finding its way down, thanks to the dissolution of carbonate rocks and the formation of a vast underground river system.

The Hamza River (port. Rio Hamza) is the unofficial name of the underground flow under the Amazon. The opening of the “river” was announced in 2011. The unofficial name is given in honor of the Indian scientist Walia Hamza, who spent more than 45 years researching the Amazon.

Largest rivers in the world

The Greatest Rivers of the World

№	Name	Length (km)	Basin area (thousand km²)	Average water flow at the mouth (thousand m³/s)	Highest water flow at the mouth (thousand m³/s)	Solid waste (million tons/year)
1.	Amazon
2.	Nile
3.	Yangtze
4.	Mississippi - Missouri
5.	Yellow River
6.	Ob (with Irtysh)
7.	Parana (from the origins of Paranaiba)
8.	Mekong
9.	Amur (from the sources of Arguni)
10.	Lena
11.	Kongo (with Lualaba)
12.	Mackenzie (from the headwaters of the Peace River)
13.	Niger
14.	Yenisei (from the origins of the Small Yenisei)
15.	Volga
16.	Indus
17.	Yukon
18.	Danube
19.	Orinoco
20.	Ganges (with Brahmaputra)
21.	Zambezi
22.	Murray
23.	Dnieper