Voçoroca is an extreme case of degradation due to erosion that requires specific care, as it causes great risks to people and enormous losses to companies and public services. Some of the damage includes:
- Road destruction
- Collapse of residences
- Total loss of arable areas
In this sense, some gullies are natural, but those that cause problems for people are often caused by human interference.
What are gullies and gully erosion?
Gully erosion is defined as continuous depression on the land resulting from soil erosion through water wear. So, that is why gully erosions are so common in hillside areas.
Therefore, the steeper the terrain and the greater the amount of rain, the greater the chance of gully formation. The risk increases even further depending on the type of soil, as some are naturally more sensitive to degradation.
Furthermore, it is important to know that a gully does not start out big. In fact, gullies in general are small in their initial phases and gradually increase in size if they are not taken care of. An example of this is the infamous Buriticupu gully, in Maranhão.
What causes a gully erosion?
Despite the fact that some gully erosions can be natural, most of the problematic ones are not. They are the result of bad soil management and deforestation over a long span of time. In addition, climate change has been aggravating not only the ocurrance but also the gravity of erosions and gully erosions in the world.
In either case, however, the process of formation of a gully erosion is similar: the soil structure is destroyed and the soil is removed and transported to lower areas of the relief.
In turn, the soil structure can be destroyed by some natural phenomenon or by human interference.
A clear example of this is mining activity, which drastically interferes with the configuration of the soil during the mineral extraction process and exposes the soil to the negative effects of erosion.
Another visible example is agricultural and livestock activities. In both cases, it is necessary to remove unwanted vegetation and prepare the soil for the cultivation of the desired species (corn, pasture, etc.).
Also, in the case of livestock farming, there is also the effect of cattle trampling the soil, which can negatively impact its structure. When not managed in time, a situation like this can result in the large amount of degraded pastures that exist in Brazil today.
How to avoid the formation of a gully?
Avoiding the formation of a gully is always the best course of action in these cases. To achieve this, good soil management practices must be used, paying special attention to the type of soil and slope.
On the other hand, if this has not been done, it is possible to recover huge gullies in their initial stages at no cost. This is because, in the beginning, the gullies can be small, which makes it easier to implement a program to recover degraded areas.
Since gully erosion generally begins after laminar erosion is installed on a piece of land, measures must be taken to prevent further soil loss. Some common strategies are:
- Installation of geotextile blankets;
- Installation of retaining walls;
- Creation of barriers with different materials.
In this way, untreated erosion turns into a gully, which compromises the safety and livelihood of many people.
Is it possible to recover a gully erosion?
The good news is that it is possible to recover such areas, but to do so, it is necessary to involve professionals from geotechnics, civil engineering, forestry engineering, geography, among other fields of knowledge. However, the technical and financial viability of this recovery is always assessed on a case-by-case basis.
Thus, gullies are the result of progressive soil degradation. This degradation originates mainly from water erosion and is worsened by factors such as soil fragility, relief slope, frequency and intensity of rain, among others.
Gully erosion, in addition to causing damage to the landscape, put the lives of entire communities at risk and contribute to the worsening of climate change.
Although the best strategy is always prevention, it is possible to recover areas degraded by gullies.
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