The rivers have different formations along their trajectory. One of them is the meander. It is the curve of the river that is formed during the course of the tributaries as a result of the fortune of the current that drives them. The steepest curves of rivers are identified as meanders and have a limited duration of time.
In this article we are going to tell you everything you need to know about the meander, its characteristics and its formation.
Key features
Meanders are used to characterize specific types of rivers based on their design. There are three types of tributaries: braided, straight, and curved or serpentine. In the rivers that flow through the floodplain, meanders are usually easier to form when the slope is small. This phenomenon can also be observed in the Amazon River, an iconic example of this type of training.
The sediment is usually deposited in the zigzag bulge and then moves from there to the bank. In the recesses, erosion dominates, and it is obvious how the embankment retreats due to centrifugal force. When the advance of the embankment in the convex zone combines with the retreat of the concave zone, the river's course begins to migrate, and meanders occur. An example of a famous meandering river is the Colorado River.
It is easy to identify or distinguish from other types of rivers, because its main characteristic is the very obvious meandering curve it forms in the riverbed. Sometimes they are named after the region of their origin. They are called galachos in the Ebro river of Aragon, and they are called swamp along the Mississippi River in the United States.
When the meandering flow forms a very large curve, it can cause the course of the river to change. They are constantly moving in some areas, such as the plains, so they can form a so-called meander-shaped lake at a certain point. The winding process of each river is different because it depends on its flow, the speed of the water and the materials that make it up.
How the meander is formed
The water in a river always flows in one direction, which is determined by the slope of the terrain on which it moves, although sometimes the surface appears flat.
To test it, you can do a simple experiment. Put the water into the pipe, it can be seen that the water replenishment speed increases or decreases; the speed depends on the inclination of the pipe.
The same goes for the river bed. The water flows in the canal; the steeper the terrain, the greater the speed of the water flow and therefore the greater the force on it. It is this force that is eroding the land, causing the river channel to curve.
As the river moves over the porous, permeable surface, the edges of the natural passage through which the river continues to flow erode. As it wears out acquires a characteristic concave shape, which creates a curve.
According to geologists, the meandering process occurs in three steps: corrosion, erosion and wear. First, the rapid power of the water or the pressure of the water corrodes the river bank and carries away soil, stones and rocks.
So this material moved by the force of the water helps to erode the river bed. Finally, the particles of the separated and colliding elements collide; this causes wear, which increases the force that destroys the foundations of the river bed.
In the same way that outward erosion forms a curve, sediment also accumulates on the opposite bank, forming the convex or inner side of the curve. Fluvial channels are generally formed in the middle and lower reaches of rivers; rarely occur at the source. This is because it is in the lower or middle part of the river where the current brings the greatest pressure and force. Meanders can change the landscape and even change the course of the river.
Meander types
There are very obvious twists and other slight twists; this is due to the centrifugal force of the water as it passes through the curve. The size of the river also has an impact: the larger the river course, the more obvious the twists and turns.
The power of the water can also be reduced. In this case, the curve fills with deposits until the current stops flowing through the sector and the zigzag disappears. Replaced by a "meander-shaped lake," this modified common name. There are several types of meanders:
Embedded meander
It is a kind of deep damage in the rock of the river bed. When the relief of the ocean current circulation increases due to tectonic movement, the meandering waterway resumes its downward erosion process. This process is called rejuvenation.
Meandering valleys are like the valleys that form the Colorado River in the Grand Canyon in the United States, which are perfect examples of how these structures form. When sea level drops, the water droplet can also form an embedded meander. There are two types of embedded meanders:
Meander widened
It is a lateral movement, which is very limited due to the decrease in the level of the baseline and the consequent decrease in the speed of the water flow. It has a sedimentary slope in the part that protrudes from the bank and another erosion in the part that protrudes.
Valley meander
It is a meander installed correctly because it does not cause significant lateral movement. It is formed by the flow of water floating on an almost flat plateau with few depressions. As it descends the basic level of river water, turbulent currents create deep cuts in the ground.
Rambling meander
It is a free meander, very common in alluvial plains with few slopes or unconsolidated sediments. This allows the curve to evolve over time; it is considered another type of zigzag.
Cancelled
It is formed when an embedded meander is cut to form a horseshoe-shaped lake. The rest of the land is known by this name. An example is Lake Powell in the southwestern United States, also known as "El Rincón." These horseshoe-shaped lakes originated when the meanders got bigger and began to cross and cross each other. The riverbed does not have an active water flow; Over time, these abandoned river tributaries dry up and fill with sediment.