River erosion: what it is, types, consequences and examples

To start this topic, we will first talk about the definition of river erosion and its characteristics . We can say that this type of erosion is the wear of the land surface produced by the water channeled into river waters , that is, the water of rivers and also in streams, torrents or other water currents. The moving water constitutes a powerful agent capable of modifying the relief and the different geoforms that its passage originates make up the fluvial relief .

In addition, the passage of water carries sediments and other materials with it, modifying their distribution in the earth’s crust. This dragging process is known as river transport and precisely the material that carries the water is called cargo and is classified into:

• Dissolution charges: are those particles that dissolve in water, therefore it has a transparent color.
• Suspended charges: these are the particles that remain in suspension, causing turbid waters.
• Bottom loads: these are those larger rock fragments that remain at the bottom of the bed and are transported by rolling, dragging or jumping.

By way of synthesis, the causes of river erosion are related to the energy of the water when it is in motion. However, the speed that the water acquires is not constant along the riverbed, so we will tell you about the different phases of river erosion:

• Mechanical phase: occurs at the highest levels of the water body channel. Here the current has great speed and consequently there is the greatest wear of the rocks by mechanical action.
• Intermediate phase: as its name implies, it occurs in the intermediate levels of the water body channel. In this phase, erosion by mechanical action continues, but as the current slows down, sedimentation begins to act .
• Sedimentary phase: it happens in the final part of the water body channel. There all the eroded material arrives and, due to the slower speed of the water, sediments are deposited. Here we talk about sedimentary rocks: types, classification and examples .

We also recommend you read this other article on What is soil erosion, its causes and consequences .

Now that we know what river erosion is and what it consists of , we will delve further into the subject and we will tell you about the different types of river erosion that exist:

General erosion

It is a decrease in the river bed produced by an increase in the carrying capacity of a current during a flood.

Erosion due to channel narrowing

It occurs mainly in those riverbed segments in which some engineering work was carried out, such as bridges or channeling. In this way, when the channel is reduced, the speed of the current increases and also the transport of sediments.

Erosion by curve of the riverbed

It is frequent that in the curves of the channels, a centrifugal force of the water is produced that consequently increases the erosion of the bed. Greater depths are reached there.

Local or localized erosion

It is produced by singularities or obstacles present in the channels. These can cause changes in the flow of water, increasing its erosive power. However, in this type of erosion the general conditions of the water flow are not modified.

The reliefs formed by river erosion are one of the consequences of this process. However, we must mention that within river processes, river floods also occur, which are river overflows that cause excessive water content around the riverbeds. River floods not only wear down the surface of the riverbanks but also, depending on the geographical location where they occur, can cause great economic losses and even fatal disasters. Undoubtedly, moving water has enormous power that goes beyond the formation of relief.

Finally, in this section we will briefly describe some examples of river erosion :

Meanders

It occurs as a result of sediment carry-over. These begin to settle in the middle course, where the speed of the water begins to decrease. Under certain circumstances, the erosive force also acts on these deposits, wearing them down and transporting them to other parts of the course. As a result, sinuous deposits form that we call meanders.

In this other article we will tell you more about what a meander is, its characteristics, formation and types .

Deltas

The deltas coincide with the end of the erosive process and take place at the mouth of the water courses. There the largest settling of the sediments carried away occurs. Therefore, deltas are sedimentary terrains.

River terraces

Also called alluvial terraces, they are sedimentary platforms in river valleys, which are formed by the deposit of sediments in those parts of the watercourse where the slope and, therefore, the speed of the current is lower.

Now that you have learned all this about river erosion, we encourage you to continue discovering information about this type of process with these other AgroCorrn articles on Types of erosion and water erosion: types, causes and consequences .