To date, 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 - a stream. So, for example, if you add the length of all the rivers in Russia, you get more than 8 million kilometers. Their total number, counting large and small, is approaching 2.5 million. The largest rivers on the globe are not more than 50, and their total length is about 200,000 km. But what does the river consist of , what is the source and mouth of the river?
The geographic significance of the river
A river is a stream of fresh water that 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 a stream of river water follows. It is usually fixed, sinuous in shape with alternating shallow and deep places. Due to geographical changes or other factors, the riverbed can change, leaving behind itself holes and depressions. So, for example, in India there is the Kosi River, it almost every year paves a new path for itself, washing away everything that meets on its way.
- The source is the beginning of the river. It can be a spring, a melting glacier, any other body of water or a place where two water streams merge.
- 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 certain area with which all water is collected. All basins are divided by watersheds; their elevation plays a role.
The main parameters of the characteristics of the rivers
The main characteristics of rivers are size, flow rate, water flow, runoff, drop and type of food.
Fall is the difference between the heights of the source and mouth. The higher the drop, the greater the flow velocity in the river.
The flow rate is measured in m / s. Not everywhere it will be the same, the sites have different terrain and the slope of the channel is different.
The 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: by rainwater, after melting ice, from underground sources and glaciers. Rivers located in the tropics feed on rains. Snow feeding near the temperate rivers and located in the northern hemisphere, and mountain rivers have glacial. There are several main types of river nutrition :
- Equatorial - only rains all year round.
- Subequatorial - the river is fed by rains, but it is uneven, and seasonal.
- Subtropical - rain with rising river levels in winter and shallowing in summer.
- Subarctic is a snow food that provides water level rise in summer and sharp shallowing in winter, when most of the rivers freeze.
- Ozerny - the river is fully fed throughout the year and does not depend on other types of nutrition.
- Mountain - in high mountains at night the rivers become shallow, and replenish during the day due to the melting of glaciers and snow.
You can also often 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 river regime is the course of long-term, seasonal and daily changes in the river flow in the channel. Changes can occur very quickly, it all depends on where and in what conditions the river flows.
Rivers flow among the plains, flow down from the mountains, in their entire lives they can change their path several thousand times, become shallow or, conversely, become more full-flowing.
Features of the flow of rivers
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 course, and there are those where the water runs at such a speed that it can carry any, even the biggest obstacle in its path.
The nature of the flow and the speed of the river depend on the topography, slope and water fall. On the plains, river flows are wide, calm, and their slope is small. These rivers include the Volga, Danube, Dnieper, Neman. But there are those that take place among the mountain hills. They are distinguished by stormy and strong currents, on their way there are many rapids, and sometimes high waterfalls. Such rivers have a huge magnitude of fall, which means that the nature of the course is completely different. Such flows include the Terek, Rioni, Tiger and Yangtze.
The climate determines the full flow, regime, and sometimes the nutrition of rivers. In humid conditions, the rivers remain full-flowing at any time of the year, and in a dry climate they very often dry out and feed only on precipitation, and there are not many of them in a year.
Mountain rivers are cold, as they feed on melting glaciers located on the peaks. But if you walk along the entire channel of the river, then at the very end of the water it can be very warm, since during its journey it heats up under scorching sunlight.
What is a mountain and plain river?
Already managed to figure out what the river regime is, but what type of river are there? After all, they can simply run among the plains or descend from high mountains.
Plain rivers are water streams that pass through a flat area with small clones and flow rates. Similar rivers flow in developed valleys with a winding channel, where stretches and rifts alternate.
Mountain rivers originate in the mountains or foothills. They have steep slopes and stony channels cluttered with rock fragments. Such rivers are characterized by large slopes and speed, small depths. Often, waterfalls and rapids occur along the paths of these rivers; erosion processes also prevail.
There are also mountain-plain rivers that start far away in the mountains, after which they gradually turn into a quiet flat river.
5 largest rivers of the world
The name of the rivers, the largest in the whole world, is known to everyone. 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 Ukayali 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 the African Nile River. It is considered a sacred river, because only thanks to it can people live in the harsh and very dry climate of Africa. During rains, the river overflows, allowing the people of Africa to engage in agriculture, rice is grown on its banks. The length of the second major river in the world is slightly more than 6,800 km, and the river basin has an area of more than 3 million square meters. km
The Yangtze is another major river in the world, which is considered the main deepwater stream of Eurasia. This river can be considered a mountainous plain, since it originates in the Tibetan plateau, then passes 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 the Yellow River, is another major river in the world that has a 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 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 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 its journey in China.
The major rivers of the world are of great importance for the industrial and economic development of the states in whose territories they flow. Rivers give life-giving moisture to people. In addition, there are many fish in the rivers that feed not only animals, but also humans.
List of the smallest rivers in the world
But not only large rivers exist on the planet. There are also the smallest, which are important for people living on its shores. The smallest rivers:
- Reproi - this river flows in Abkhazia, and its length is only 18 meters. Moreover, 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 not 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 streams that attract attention with their originality.
Caño Cristales is the most colorful river in Colombia. Most often, locals call it a 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 at the water in it, you would think that the rainbow fell into the water.
Tsitarum is the dirtiest river on the planet. It is located in Indonesia, and it is dirty because more than 5 million people live in its basin. People dump all waste into its waters. If you look at the river from afar, you don’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 volcano Purase 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 the Rivers: Plants
The characteristic of rivers is not only nutrition, length and other parameters, but also animals with plants. Indeed, each water stream, whether it is the largest or smallest, has its own life. In each fast or quiet river, many plants found their refuge, 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 to grow at the bottom of the river, and their upper part rises above the water. These include reeds, reeds, horsetail, cattail and arrowhead.
- Plants whose roots attach to the bottom and leaves float on the surface of the water. Such plants are white water lily and pond floating.
- Plants with roots at the bottom, whose leaves remain in the water - this is urut and ordinary moss.
- Floating plants with no roots at the bottom. One of these plants is duckweed.
- Plants that live in the middle layer of water are hornwort, filamentous algae and elodea.
River Life: Animal Life
The characteristic of rivers is 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 hover in a pond and are given to the power of the current. Plankton is the main food for many fish.
- Benthos. This group includes bottom organisms.
- Necton is an actively moving animal that can overcome the course. Today, there are more than 20 thousand species of nekton, including fish, squid, cetaceans, pinnipeds, turtles, and others.
- Neuston - animals and plant organisms that live on the surface of the water, bordering the atmosphere.
- Pleistons are animals and plant organisms that are semi-immersed in water, that is, capable of living simultaneously in both aquatic and air environments.
- Epineuston includes organisms that live on a surface film.
- Hyponeuston - organisms associated with the surface film, but living under it.
- Periphyton - organisms that live on the surface of objects immersed in water.
Mammals 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 ponds, so that it was easier for them to engage in everyday life. The use of the river helps not only to do household chores, but also to manage their household. The water from the rivers is used for drinking, purifying it first, food is prepared on it for itself and animals, and it is used for watering plants.
Today, water from rivers is treated at special stations and piped to the houses of large cities. Also, rivers are often used for rafting forests, as a way to travel long distances. In the rivers they bathe, fish. Rivers are also very beautiful landscapes, because it is 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, which are also building closer to rivers ?! Thanks to this neighborhood, any enterprise will be able to eat water from a reservoir. In distant countries - Africa or South America - where the climate is very dry and the rivers often dry up, these rivers, even if they are dry in some places, are the main source of drinking for wild animals. But in the rainy season they again become full-flowing.
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 exert all their strength to preserve their purity and beauty.