We explain what river erosion is, its causes, phases and ways in which it manifests. In addition, types of river erosion.
What is river erosion?
River erosion is the effect of wear and tear on the land surface of river water . In other words, it is the particular way in which water modifies the landscape , whether it is flowing over the surface or in underground currents, thus dragging sediments, materials and altering its distribution in the earth’s crust.
In fact, water is one of the main erosive factors of our planet , whose action on the earth’s crust takes many forms: the tide, the waves, the rain, and also the flow of the rivers. In the latter case, we refer to waterfalls, caves, gorges, meanders, canyons, deltas, estuaries and other landscape alterations created in its path.
Despite its strong erosive impact, this flow of matter and energy is essential for the redistribution of different chemical elements and their entry into other important biogeological cycles .
River erosion is due to water energy, as well as the transport in it of numerous materials, which impact the earth’s crust, modifying it. This can happen in two different ways :
- Surface erosion , when it occurs due to the surface flow of water, which dissolves solid materials and clays, exposing the underlying materials and depositing the dissolved materials in new locations.
- Erosion of the bottom of the riverbed , when it occurs due to the mechanical action of the water and the materials that it can drag, such as boulders, blocks, etc., or sands dissolved in it, all of which impacts on the surface of the bottom of the riverbed.
And also in three separate phases:
- Mechanical phase . The one with the highest activity, in the highest regions of the river, where the greatest wear due to mechanical action occurs, as a result of water energy and the impact of other materials.
- Intermediate phase . Located later in the riverbed, it still has erosive mechanical effects, but already in the middle of other sedimentary processes in which the worn matter begins to settle.
- Sedimentary phase . Towards the end of the riverbed, the mechanical effect of water is much less intense, but its sedimentary effect is much higher, thus depositing all eroded material and creating new geological forms.
Types of river erosion
According to their specific causes and forms of action, we can classify river erosion in:
- General erosion . It lowers the riverbed in long stretches, affecting it in the long term.
- Erosion due to narrowing of the channel . It takes place in segments of the channel in which engineering works were carried out (such as bridges, channeling, etc.) that cause the reduction of the channel, thus increasing the speed of the current and therefore the transport of sediments.
- Erosion by channel curve . Typical, as the name implies, of the curvatures in the riverbed, due to the addition of the centripetal force to the energy of the water on the outside of the curve.
- Localized erosion . Also called local erosion, it is due to the action of complex flows, with speeds that require bi-dimensional or three-dimensional considerations.