The meaning of rivers
Rivers are the most important sources of fresh water, without which people, plants and many animals would die. On our planet, large spaces are occupied by oceans and seas, but the water in them is salty and not suitable for drinking.
From the very beginning of the human race, people tried to settle on the banks of rivers. Clean river water provided life. Thanks to it, people could cultivate the land and grow plants, take domestic animals to water, bathe and wash clothes.
Rice. 1. Ancient settlements near rivers.
Rivers were of great importance not only in summer, but also in winter, when they were bound by a thick layer of ice. During the warm season, merchant ships sailed along them, and with the onset of cold weather, merchants transported their goods on large sleighs directly across the ice.
Don
River Don
The water artery is the oldest stream in Russia. It washes the Voronezh, Lipetsk, Volgograd and Rostov regions. The source is located on the Central Russian Upland, the mouth is the Sea of Azov. The length of the channel is 1870 km, the water basin occupies 422,000 square meters. km. The width of the stream rarely exceeds 20 meters, the average depth is 10 meters. There are busy areas with rapids and riffles.
The Don's path passes through the forest-steppe and steppe zones, the water regime differs from the northern streams. The riverbed is fed by melted snow and rain. Flood occurs in the spring, during active snowmelt. In summer, autumn and winter there is low water. By December, stable ice cover is established. The autopsy is scheduled for March.
The river has a flat character with a calm flow, so in the old days the stream was called the “quiet Don”. On the banks there are Voronezh and Rostov-on-Don, regional centers and cities with a population of millions. Outside Rostov, the Don delta begins to form, where it breaks up into branches.
Where do rivers flow from?
As you know, every river has its own beginning - a source. It can be very different:
- small spring or stream;
- a huge bubbling waterfall;
- melted glacier or snow cap on the top of a mountain.
With the arrival of warmth, the snow in the mountains begins to melt. Thin streams appear, which quickly flow down, merge with each other and form a mountain stream. Such rivers are characterized by very cold water, high speed and force of water flow. Mountain streams can destroy any obstacle in their path; they are very unpredictable and dangerous.
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Rice. 2. Mountain river.
In the spring, when the snow melts, all the rivers are replenished with new water and become full-flowing. Sometimes it gets to the point where they flood the coastline. In this case, people living nearby suffer greatly: they may lose their shelter and crops.
Current is one of the main characteristics of rivers
A current is the movement of a mass of water in a certain direction.
All rivers flow through different areas with reliefs that are different from each other, water level changes change, additional water flows enter the river, this leads to the acceleration of the river. In addition to the terrain, the increase in current speed is also influenced by the following factors:
- Wind.
If the speed and strength of the wind are strong, and it blows in the same direction as the river flows, then the speed of the current will be greater.
- Water temperatures
Water flows with different temperatures increase the speed of the river, this happens when several tributaries merge.
Along the river there are rapids, rocky areas with fast currents and a steep riverbed. They make it difficult for ships traveling on water to move.
There is a statement that all rivers flow from the northern part to the southern part, that is, in the same direction. This is not true. Water flows move under the force of gravity. The water flow can be either from north to south or from south to north.
The rivers flowing south in Russia are:
- Volga
- Ural
- Neva
- Don
Moscow River and Mother Volga
The main river of the capital of Russia is called the Moscow River.
Settlements along its banks appeared in the Stone Age. In the 8th century, the Slavs inhabited the river, building their villages. The Moscow River connected the city with the Volga, Don, Smolensk and Novgorod; timber was floated along it, trade was conducted, and the river provided food and water. In addition, the Moscow River protected the city from enemy attacks from the south.
The river flows through the territory of the Moscow region, partly through the Smolensk region. It starts in the Starkovsky swamp, where it is narrow and looks like a stream. The length of the Moscow River is 500 km; within the city limits its banks are concreted, there are no natural ones.
The water in the river is polluted and contains high levels of petroleum products and heavy metals. You cannot swim in such water, but there are several beaches where the ecological situation is better and there are places for bathing for city residents.
The Volga River is the queen of Russian rivers, it is called Mother Volga.
The Volga belongs to the Caspian Sea basin. Its source is located in the Tver region, it is a small spring near the village of Volgoverkhovye. The Volga has 150,000 tributaries, the length of the river is about 3,500 km.
Cities on rivers
There are many cities, villages and towns on the Volga. The most numerous among them:
- Kazan
- Saratov
- Volgograd
- Astrakhan
- Yaroslavl
- Tver
- Cheboksary
- Ulyanovsk
The Oka is one of the largest tributaries of the Volga. There are 19 cities on the Oka River, among them Kaluga, Ryazan, Kolomna, Murom, Aleksin, Serpukhov and others.
The Ob River flows through the city of Novosibirsk. In Russia it is the longest river; in Asia the Ob ranks second in length. It is formed by the confluence of two rivers - the Biya and the Katun, in Altai.
The beautiful city of St. Petersburg is located on the Neva River. In addition to it, other cities of the Leningrad region are located along the banks of the Neva - Otradnoye, Kirovsk, Shlisselburg.
Krasnoyarsk is considered a city on the river. The Yenisei, on which it stands, is in second place in length after the Ob. It is also the deepest river in Russia.
Cities located on rivers have been rich since ancient times, actively developed trade relations, and grew rapidly. In those days, travel by land was very slow and inconvenient, so river routes served as the main roads for transporting goods. They transported goods, building materials and people. River water could be used for food. Now this cannot be done because of the environment.
Rivers and their beds
Large and small, mountain and lowland rivers flow, forming a complex web on the surface of the planet. There are more than 2 million rivers in Russia. Of these, there are more than two hundred large rivers, along which even large ships can pass. There are also small rivers that cover the bottom with water.
The quantity and speed of water flow determines what its channel will be: wide or narrow, deep or not. The bed of each river has its own characteristics, but this does not in any way affect the composition of the water - it always remains fresh.
Rivers carrying fresh water
There are many different rivers on planet Earth - large and small, wide and narrow. There are from 2.5 to 4 billion rivers in the world. There is not a single salty river, they are all fresh. Rivers are an important drinking water resource. Another purpose of river water is its use for irrigation of agricultural land and for industrial purposes.
Question:
What kind of water is called fresh?
Unsalted water is considered fresh. All rivers are fresh. Such water is the key to life on the entire planet Earth.
Fresh water makes up only 2.5% of the total water resources on Earth. Most of it is glaciers and snow covers that are inaccessible to humans. Rivers, lakes, streams, ponds and other reservoirs contain about 0.25% fresh water. Fresh water is considered an eternal resource that cannot run out, but due to climate change, human activity, and overpopulation of the entire globe, the problem of fresh water exists.
Scientists say that if in the near future humanity does not learn to desalinate water, use it economically, and create a large number of fresh water bodies, then there will be a shortage of drinking water. This can lead to wars and disasters in countries where water resources are available in small quantities.
Our country is in second place in terms of the amount of fresh water. Lake Baikal is considered the largest natural freshwater reservoir.
Fresh water reserves in Russia are huge, but there are regions in the Russian Federation where drinking water is delivered only by equipment.
Causes of fresh water in river systems
The main reason why the water in rivers is fresh is precipitation. They contain no salt at all. Rain falls into the ground, mixing with dust, minerals and salts. The water is enriched with various impurities, and rain streams flow into rivers, which, in turn, flow into the seas. Under the influence of sunlight, water evaporates from the surface of the world's oceans, but the salts do not evaporate, but remain in the water. Atmospheric precipitation falls again fresh. This continues endlessly, this phenomenon is called the water cycle in nature.
Rivers and seas: differences from each other
The salinity of sea water is one of the main differences between a river and the sea. Besides this, the differences between a river and the sea are as follows:
- The river is in motion, the sea is not flowing;
- The area of the sea is much larger than any river, because of this, the shores of the river are visible, while the shores of the sea are not visible, or only one is visible;
- The river flows into the sea, it cannot be the other way around;
- There may be waves on the river, while on the sea, in addition to waves, there are storms, ebbs and flows;
- Rivers can flow into each other, seas cannot;
- In the seas there is a wide variety of flora and fauna, in rivers there are fewer representatives of flora and fauna;
- The current in the river is directed in one direction, but sea currents can be multidirectional.
Where do the rivers end?
In summer, in hot weather, moisture evaporates: river sources become shallow, and the rivers themselves become less full-flowing. After the spring melting of the snow, they return to their usual channel and flow to their destination - the mouth. It could be:
- another river;
- lake;
- sea;
- ocean.
Most of the large and small rivers of Russia flow to the Arctic Ocean, and only a small part of them flows into the Atlantic Ocean.
Rice. 3. Arctic Ocean.
1) Remember what you know about rivers and seas. Think about where the rivers flow.
A river is a water stream that flows from source to mouth.
The river flows into the sea, a large body of salt water. The sea is part of the world's oceans. But rivers can also flow into a lake or get lost in the sand.
2) To answer this question correctly, let us trace the path of the water traveler in the figure.
Traveling water begins its journey from small streams. Rodnikov. They merge with each other and form small rivers, for example the Sturgeon or the Moscow River. These small rivers flow into larger rivers, such as the Oka, which flows into an even larger river, the Volga.
And this huge river flows all the way to the sea and flows into it. The path of the water traveler ends at the sea.
Mountain and lowland rivers
Due to the characteristics of the terrain through which rivers flow, the nature of the river’s flow is determined. It can be mountainous, flat or mixed.
Question:
What rivers are called mountain rivers?
Mountain rivers are water streams that flow through a narrow, deep valley, pass through mountainous terrain and have a restless and fast flow. Mountain rivers of Russia include:
- Samur
- White
- Ural
- Sulak
- Terek
- Ufa
- Biya
A mountain river originates high in the mountains. Most of them are formed from melting glaciers and snow located on the peaks. The water of mountain rivers is very cold.
A flat river is a body of water with a calm flow, quiet character, and a wide valley. Such a river flows through flat terrain.
Question:
How do mountain rivers differ from lowland rivers?
Lowland rivers are characterized by:
- Calm current
- Warm water compared to mountain rivers
- Less tortuous trajectory
- A small difference in height between the source and the mouth
In the summer, small reservoirs can dry up, and with the onset of the autumn flood they are filled with water again.
The largest lowland rivers in Russia include:
- Irtysh
- Ob
- Yenisei
- Angara
- Lena
- Kolyma
- Vilyui and others
The mixed nature of the river flow combines both flat and mountainous. When a mountain river enters a flat area, its appearance changes, the channel becomes wider, the flow slows down, which once again proves the dependence of the nature of the flow on the relief.
The regime and nutrition of rivers depends on the climate where the water flows. If it rarely rains and the climate is dry, then rivers may dry up.
The area located across the river is called a district.
An area located along a river or among mountains is called a valley.
Rivers erode rocks, banks, and coastal rocks with their currents and carry them away with their waters. There are slopes on the sides of the valley; they can be gentle or steep, high or low. The valley also has a bottom - its lowest and smoothest part, terraces - areas located at different heights from the bottom, an edge - the place where the slopes connect with the surface, and a bottom - the place where the bottom and slopes connect.
The valleys are very beautiful, there is no shortage of water, so there is a lot of greenery and grass.
The age of the valley and the degree of its development are indicated by its shape. Narrow valleys with steep slopes, gorge with no terraces, not wide - these are young valleys.
Gentle slopes with a deep channel characterize the mature valley.
Since ancient times, people have located their pastures, crops, and settled on the terraces and floodplains of valleys.
The largest rivers on Earth include:
- Amazon
- Nile
- Yangtze
- Yellow River
- Ob
About 20% of all fresh water is concentrated in the Amazon River, located in South America. The number of tributaries and straits of the river is so large that it is difficult to count them.
Most of the Nile flows through Egyptian territory; it is a deep river. During floods, the Nile changes color. Due to the presence of minerals in the water, the river turns red, and due to the large abundance of aquatic plants, it turns green.
The Yangtze is a river in China belonging to the East China Sea basin. Of the Eurasian rivers, the Yangtze is the longest river.
Translated from Chinese, the Yellow River means “yellow river.” The color of the waters of the Yellow River is really yellow-brown. The river becomes muddy due to the washing out of clay from its upper reaches.
The Ob flows through Western Siberia. Its flow changes several times in different directions.
