Today, no one can say exactly 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 we count large and small, approaches 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 is the river made of, what is the source and mouth of the river?
Geographical significance of the river
A river is a stream of fresh water that moves in a fixed channel and is replenished mainly by precipitation. Before understanding the characteristics of freshwater streams, there are a few key terms to remember:
A channel is a depression along which the flow of river water follows. It is usually fixed, sinuous in shape, with alternating shallow and deep places. Due to geographic changes or other factors, the riverbed can change, leaving holes and depressions behind. So, for example, in India there is the Kosi River, it paves a new path for itself almost every year, washing away everything that meets in its path
- The source is the beginning of the river. It can be a spring, a melting glacier, any other body of water or a confluence of two streams.
- The mouth is the place where the river ends, it flows into the sea, ocean or other water stream.
- The river system is not only the river itself, but also its tributaries.
- A river basin is a defined area from which all water is collected. All basins are separated by watersheds, their role is played by hills.
Basic parameters of river characteristics
The main characteristics of rivers are their size, flow rate, water flow, runoff, 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 the current in the river.
The flow velocity is measured in m/sec. It will not be the same everywhere, the sites have different terrain and the slope of the channel is different.
Water flow rate shows how many cubic meters passed in 1 second through the cross section of the channel.
The river is fed in several ways: rainwater, after the melting of ice, from underground sources and glaciers. Rivers located in the tropics feed on rain. Snow feeding near the rivers of temperate zones and those located in the northern hemisphere, and mountain rivers have glacial feeding. There are several main types of river feeding:
- Equatorial - only rains all year round.
- Subequatorial - the river is fed by rains, but it is uneven, but seasonal.
- Subtropical - rainy with a rise in the river level in winter and shallowing in summer.
- Subarctic is snow nourishment, which provides a rise in the water level in summer and a sharp shallowing in winter, when most of the rivers freeze over.
- Ozerny - the river is fully fed all year round and does not depend on other types of food.
- Mountain - in the high mountains at night, the rivers become shallow, and during the day they are replenished due to the melting of glaciers and snow.
It is also very common to hear about the regime of the river. But not everyone knows what a river regime is. What does it depend on? The answer is very simple, the regime of rivers is the course of long-term, seasonal and daily changes in the flow of the river in the channel. Change can happen very quickly, depending on where and under what conditions the river flows.
Rivers flow among the plains, flow down from the mountains, in their entire life they can change their path several thousand times, become shallow or, conversely, become more full-flowing.
Features of river flow
What is the source and mouth of the river is already known, but what are the features of the flow of water 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 runs at such a speed that it can demolish any, even the biggest obstacle in its path.
The nature of the current and the speed of the river depend on the relief, slope and fall of the water. On the plains, river flows are wide, calm, and their fall slope is small. These rivers include the Volga, Danube, Dnieper, Neman. But there are also those that flow among the mountain heights. They are distinguished by stormy 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. These streams include Terek, Rioni, Tigris and Yangtze.
The full flow, regime, and sometimes the feeding of rivers depend on the climate. In humid conditions, the rivers remain full-flowing at any time of the year, and in a dry climate they very often dry up and feed only on precipitation, and there are not very many of them during the year.
Mountain rivers are cold, as they are fed by melting glaciers located on the peaks. But if you walk along the entire course of the river, then at its very end the water can be very warm, as during its journey it heats up under the scorching sun.
What is a mountain and lowland river?
Already figured out what the regime of a river is, but what types of rivers are there? After all, they can simply run among the plains or go down from the high mountains.
Flat rivers are water streams passing through flat terrain with small slopes and flow speeds. Such rivers flow in developed valleys with winding channels, where stretches and rifts alternate.
Mountain rivers originate in the mountains or foothills. They have steep slopes and rocky channels, cluttered with rock fragments. Such rivers are characterized by large slopes and flow rates, shallow depths. Often on the way of these rivers there are waterfalls and rapids, and erosion processes also predominate.
There are also mountain-flat rivers that start far in the mountains, after which they gradually turn into a quiet flatriver.
5 biggest rivers in the world
Every person knows the name of the largest rivers in the world. The list of the 5 largest and deepest rivers in the world is headed by the Amazon, which is considered the heart of South America. More recently, it was considered 2 in the list of the largest after the Nile. But after scientists took 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.
The second place was taken by the African Nile River. It is considered a sacred river, because 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 people of Africa to engage in agriculture, and rice is grown on its banks. The length of the second largest river in the world is a little more than 6800 km, and the river basin has an area of more than 3 million square meters. km.
Yangtze is another major river in the world, which is considered the main deep-sea stream of Eurasia. This river can be considered a mountain-flat 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.
Huanghe, or the Yellow River, is another major river in the world, which has 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 name of the rivers located on the territory of Russia can be found on the map. Among them there is one that is included in the list 5the largest is the Ob. Its length is slightly more than 5400 km, and the basin area is almost the same as that of the Nile - 3 million square meters. km. This water stream originates in Russia, and then passes through Kazakhstan and ends in China.
The world's major rivers are of great importance for the industrial and economic development of the 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 people.
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 shores. 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 characteristic of rivers is not only information about whether they are large or small in size. Also on the planet there are unusual and amazing water flows that attract attention with their originality.
Cano Cristales is the most colorful river in Colombia. Most often, locals call it the river of five colors. The river acquires such a bright and unusual variety of shades thanks to the algae living in its water. If you look atwater in it, you might think that the rainbow fell into the water.
Citarum is the dirtiest river on the planet. It is located in Indonesia, and dirty because more than 5 million people live in its basin. All waste is dumped 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 are looking at a landfill.
Congo is the deepest river on the planet. It flows in Central Africa, in some places its depth reaches 230 meters, and possibly even more.
El Rio Vinegre is the most acidic river. It flows past the Puras volcano in Colombia. Its water contains more than 11 parts of sulfuric acid and 9 parts of hydrochloric acid. No living creature can be in this river.
Life in rivers: plants
The characteristic of rivers is not only food, length and other parameters, but also animals with plants. Indeed, in every water stream, whether it is the largest or the smallest, there is a life of its own. In every fast or quiet river, many plants have found their home, which 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 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 reeds, reeds, horsetails, cattails and arrowheads.
- Plants whose roots are attached to the bottom and whose leaves float on the surface of the water. Such plants arewater lily white and pond floating.
- Plants with roots at the bottom, whose leaves remain in the water are urut and common pondweed.
- Floating plants with no roots at the bottom. One of these plants is duckweed.
- Plants that live in the middle layer of water - hornwort, filamentous algae and elodea.
River Life: Wildlife
A characteristic of rivers is also animals that cannot exist anywhere but in water. Not only a large number of species of fish live in the rivers, but also other living organisms:
- Plankton are living organisms that live in the water column, they seem to soar in a pond and surrender to the power of the current. Plankton is the main food for many fish.
- Benthos. This group includes benthic organisms.
- Nekton are actively moving animals that can overcome the current. To date, 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 the water, bordering the atmosphere.
- Pleyston are animals and plant organisms semi-submerged in water, i.e. capable of living both in the water and in the air.
- Epineuston refers to organisms that live on the surface film.
- Hiponeuston - organisms associated with the surface film, but living under it.
- Periphyton - 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?
People in ancient times believed that water is life. They often built houses on the banks of rivers and reservoirs, so that it would be easier for them to take care of everyday life. Using the river helps not only to do household chores, but also to manage your household. Water from the rivers is used for drinking, after cleaning it beforehand, they prepare food for themselves and animals, use it for watering plants.
Today, water from rivers is purified at special stations and fed through pipes to the houses of large cities. Also, rivers are often used for timber rafting, as a way to travel long distances. They swim in the rivers and fish. Rivers are also very beautiful landscapes, because it's nice to sit on the shore and enjoy the fresh, moist air while admiring the surroundings.
And how much water is needed for industrial enterprises that also build closer to rivers?! Thanks to this neighborhood, any enterprise will be able to feed on water from the reservoir. In distant countries - Africa or South America - where the climate is very dry and the rivers often dry up, these rivers are the main source of drinking for wild animals, even if they have dried up in some places. But in the rainy season, they become full again.
Without rivers, our planet would not be so beautiful and real. They, like water sleeves, braid the globe and give life-giving moisture, but the task of mankind is to make every effort to preserve their purity and beauty.
