Slopes are fragile landforms as they can collapse or fail due to sudden movements. Human activities play a crucial role in slope modification and stability. Humans can affect slopes through mining, construction and farming. These activities influence the processes (mass movements) occurring on them and its stability.
While humans affect slopes negatively, they’re the ones who can modify slopes to stabilise them, for example, terracing.
Mining
Mining involves a huge destruction of land, leaving the land degraded and filthy. On slopes, it has a huge impact. Mining adits involve excavating along hillsides which can produce large amounts of debris leading to mass movements such as debris falls, rockslides, and rockfalls.
In addition, such mines leaves the slope unstable and prone to collapse.
The blasting effect to reveal mineral seems, trucks and bulldozers produce 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.
Furthermore, 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 result in slope instability. 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 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.
In January 2022 a landslide occurred in Bigie City, Guizhou. The landslide killed 14 people and injured several others.
Outdoor Slope Activities
Outdoor activities such as skiing, hiking and snowboarding can also cause debris movements along slopes, or trigger mass movements such as avalanches if the slope is covered with snow.
Positive Human Impact on Slopes
Even though humans negatively affecting slopes, they are the ones who can stabilise them.
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.
Slope Flattening
Slopes can be graded to reduce their steepness and force of gravity
