How do Gabions Help to Prevent Soil Erosion?

In Africa, our environment has undergone significant changes due to continuous human development. Let’s discuss how we can protect slopes and reduce soil erosion, in the process protecting precious layers of top soil.

Major problems related to soil conservation and slope protection are:
  • Erosion
  • Filtration
  • Landslides
  • Rockfalls
  • Unstable slopes / embankments

In this article, we will seek to understand the causes of soil erosion and how we can solve these problems in an environmentally sustainable way.

What causes problems related to soil erosion?

The problem originates from man’s need to develop urban areas, transportation routes, and the need to use soil and land for farming whilst trying to maintain the delicate balance of the surrounding habitat.

The delicate natural ecosystem is easily affected by human activities, which tends to cause erosion and therefore needs man’s intervention to strengthen natural and artificial slopes.

The old approach to soil conservation can no longer be used, because man’s presence has changed both quantitatively and qualitatively. A reduction in the population in mountainous areas, a drop in the agricultural activities and the consequent soil conservation activities, no longer allows for the balance established by the previous inhabitants to be maintained.

On the other hand, there has been a dramatic change in the evaluation of man’s priorities towards the environment, forms of intervention and the materials used. This is primarily due to the growth of environmental awareness.

Meteorological forces, such as rainfall and temperatures acting on an area will, through soil erosion, modify the physical and structural characteristics, as well as the morphologic aspect of the area.

Landslides or surface erosion due to water runoff, are the main causes of structural instability. To solve these problems, it is necessary to control the undesired effects, without upsetting the environmental equilibrium.

Human settlements (urban or industrial), and the development of transportation routes, can be the cause of land alteration.

In the case of human settlements, it is necessary to take action to in order to limit the damage by trying to reach an equilibrium between safety and environmental evolution.

In other cases, the protective work carried out may alter the environmental balance, carefully selected to, in time, restore the original conditions.

The solutions used should aim to restore a natural new equilibrium.

An environmentally aware approach to Soil Conservation

The intervention criteria adopted need to be based on eco-compatibility test parameters.

Soil Conservation principles to consider:
  1. Effective technical solutions
  2. Blend in with the surroundings
  3. Achieve long term stability
  4. Safety of urban areas must be realised
  5. Minimum alteration of natural habitats

There are Two Main Types of Soil Conservation Solutions:
  1. Active Protection – directly acting on the causes of soil failure, thus eliminating the main problem
  2. Passive Protection – acting on any phenomenon, thus curbing their negative effects.

The choice of protection must be made in accordance with minimal environmental impact.

The design phase must be preceded by a preliminary phase of investigation and study, aimed at defining, analysing and quantifying:

  • The geological and pedological nature of the area
  • The geography
  • The climate
  • The runoff coefficient of local vegetation

Once this fundamental data has been collected, a hypothetical protection solution can be evaluated, even though it may differ from case to case, depending on local phenomena:

  • River training
  • Geomechanical consolidation
  • Regreening

Example of a balanced solution to slope instability

Here we see a mountain slope at Tokara in South Africa that had become unstable. The mountain slope was bio-engineered, using gabions, to provide extra support. Over time, the mountain slope and vegetation naturally integrated with the gabions. In this case, the gabions provided a sustainable solution.

How do Gabions work to prevent Soil Erosion?

Gabions play an important role in preventing soil erosion by providing an effective erosion control measure. Gabion structures are constructed using wire mesh baskets filled with rocks, which are strategically placed along vulnerable slopes, riverbanks, and coastlines.

They provide sturdy barriers that resist the erosive forces of wind and water, reducing the velocity. As water encounters these barriers, sediment particles settle behind the gabions, promoting the formation of stable terraces and preventing further erosion.

Gabions offer a sustainable, long-lasting solution to mitigate soil erosion, allowing for the restoration of degraded landscapes and safeguarding the delicate balance of Africa’s diverse ecosystems.


If you have a question about using gabions for soil conservation or slope protection, feel free to ask our advice.