Channel is what? River channel, its character and change
The channel is the depression in which the river flows. In this sense the term is used most often. However, it is multivalued and can be used not only in geography. What other values exist? What is a river bed and what characteristics does it have?
What is the mainstream?
The exact origin of the word linguists and historians can not be determined. According to one of the versions, it is associated with such Slavic words like “crush”, “ruh”, “dig”. Another and more common theory refers it to the Lithuanian word rusėti, which means “flow”.
In Russian, there are three meanings in which the term is used. This concept is most often found in geography, where it is treated as a bed of a river, the recess through which it flows.
The remaining meanings of the term are also close to the word "flow" or "flow." So, in anatomy, the channel is the same as a blood vessel - the cavity through which blood moves.In addition, the concept has a figurative meaning. In this case, the channel is the course or path of development, the direction in which events “flow”.
Each stream flows through the chute, which he himself creates. Rivers arise from the melting of snow, the release of groundwater to the surface, they come out of lakes or springs. Usually they appear as small streams and gradually expand, connecting with other water bodies or replenishing precipitation.
Having appeared, the flow of water slowly undermines the soil, forming a channel. This is a natural indentation along the entire path of the river. It begins at the source and stretches to its mouth (the place where it flows into another reservoir). The channel is the deepest part of the river valley.
The depth and nature of the channel depends on many factors. Its formation is influenced by the properties of soils and rocks of the area, vegetation. In some parts of the world, permafrost also affects them.
Parts of the channel
The main part of the watercourse flows through the main channel. Here the greatest amount of water is concentrated. Large rivers have a channel from 150 meters to several tens of kilometers.For example, the Russian river Ob reaches 60 kilometers wide, the Amur - 50 kilometers.
A channel up to sixty meters wide is considered narrow. These are mainly mountain fast rivers. Depth also depends on the amount of water and the speed of its movement. The deepest (60 meters) is the river of South America - the Amazon. It also has the greatest length in the world and stretches to 6992 meters.
In the upper stream, as a rule, deep. It is actively eroded by the force of water, since its speed in this part is very high. A place that is so deep that it is enough to pass a ship is called the fairway.
In the middle part, the slope of the river may decrease, which is why its bed does not deepen with great force. His bias is also small. In the lower reaches usually accumulate parts of the soil and stones that are applied with water. From this channel rises, and the speed of the river slows down.
As the river grows, its bed increases much more slowly than the width. The waterways of the plains are often more winding than mountainous ones. This is due to the low speed and angle of the terrain.Mountain streams often form waterfalls, cascades and rapids.
The water of the flat river cannot withstand the resistance of the banks and tries to go around the obstacle. As a result, the channel "wanders", changes direction, turning in different directions. This phenomenon is called the meander. In mountain rivers, water also does not always bypass the obstacle. Flowing through hard rocks, it is unable to cope with them and it leaks right in between them, forming rapids.
The bed of the river is not constant. Changes in the river bed may occur at meandering rivers. If the curvature of the watercourse is too strong, it turns into an old woman, and then into a lake or swamp. At the intermittent rivers, the channel also changes frequently. This is due to a change in terrain during a long dry period.
The formation of rivers is a completely natural process, but sometimes people interfere here. Watercourses are often used in economic activities, sometimes there is a need to move the river to a more favorable place for this.
An artificial river channel, a canal, is formed with the help of dams and the construction of various obstacles. The canals are used for land improvement, the creation of fish spawning grounds, water transport routes and the construction of industrial facilities.