Geomorphology

Human Impact on Slopes

Denver Kunaka Last edited:September 26, 2020

Table of Contents

Contalago Favela, Rio de Janeiro, photo by Hmaglione 10 Wikipedia

Slopes are fragile landforms as they can collapse or fail due to sudden movements. Human activities play a crucial role in slope modification. Humans greatly affect slopes negatively, for example, by mining, construction and farming.

While humans are the culprits of affecting slopes negatively, they’re the ones who can modify slopes to stabilise them, for example, terracing. Humans can affect slopes by destabilising them or influence the processes (mass movements) occurring on them.

Mining

Mining involves a huge destruction of land ,leaving the land degraded and filthy. On slopes it has a huge impact. Mining such as adits involves excavating along hillsides which in turn produces large amounts of debris leading to mass movements such as debris falls, rockslides and rockfalls.

Mining on slope
Cross section of an adit mine

In addition, such mines leaves the slope unstable and prone to collapse.

The blasting effect to reveal mineral seems, trucks, bulldozers, cranes e.t.c produces vibrations which can collapse a slope or trigger soil movements.

Deforestation

The removal of trees for commercial and traditional uses negatively affects slope. This is because soil is left loose which in turn increase its mobility downslope.

In addition, run-off increases as less vegetation cover intercepts or absorbs water.

When heavy rains occur the loose soil is easily saturated with water triggering mudflows or slides.

Agriculture

The need for farming and fertile soils can drive humans to carry out their farming activities on slopes. Agricultural activities such as cattle rearing along slopes can produce considerable amounts of soil movements. In addition, vegetation may be slashed away which further weakens the slope.

Infrastructure/ Construction

Building along slopes results in slope instability and prone to collapse and mass movements such as slides are bound to occur. Many shanty houses (favelas) across Brazil are built on hill or mountain slopes and are very much affected by mass movements.

In 2010, 200 people in the Morro Bumba favela, Rio, Brazil died due to heavy rains which lubricated the already loose soil triggering slides in the process.

Rapid urbanisation in several countries such as China results in the demand for more houses, roads e.t.c. This demand forces construction on unstable slopes which are prone to collapse.

Hiking/skiing/ racing e.t.c along slopes

Outdoor activities such as hiking, skiing and rally races can also cause soil movements along slopes or trigger mass movements such as avalanches if the slope is confined of snow.

Positive impact on Slopes

By negatively affecting slopes, humans can also help to stabilise slopes.

Terracing

The building of steps along slopes greatly stabilize slopes and limits the rate of mass movements.

Afforestation

More tree planting help to bind the soil together therefore stabilise slopes and mass movements. More here: Slope Stabilisation methods

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About Author

Denver is a Geographer, Web Developer, Graphic Designer, Blogger & Digital Marketer. He has come to know that everyday there's something new to learn :-)