Soil erosion: causes and impacts Cambridge IGCSE Environmental Management revision
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In plain words
It takes hundreds of years to make a few centimetres of soil, and one heavy storm to wash them away. Soil erosion is the loss of that thin, fertile top layer, and when it goes, the harvest goes with it.
9 things to know
- Soil erosion is the removal of topsoil by wind or water.
- Water erosion: heavy rain runs over the surface and carries soil with it. Wind erosion: wind lifts dry, loose soil and blows it away.
- Bare soil erodes most easily, because nothing shelters it from rain and wind, and no roots hold it together.
- Causes linked to people. Unsustainable agricultural practices, such as overgrazing and overcultivation, strip the plant cover. Deforestation removes the trees whose roots bind the soil and whose leaves break the fall of the rain.
- Farming on steep slopes: water runs faster down a steep slope, so it carries more soil away.
- Impacts on the land. Soil washed into rivers settles on the bed. This is silting, and it makes the river shallower and more likely to flood. With its topsoil gone, land can turn to desert. This is desertification.
- Slopes that have lost their vegetation are unstable, which leads to mass movement: landslides, rockslides and mudslides.
- Habitats are lost, and biodiversity falls.
- Impacts on people. With the fertile topsoil gone, crop yields fall. That can lead to malnutrition and famine, and to the displacement of people, who leave land that can no longer feed them.
Worked example
Trees are cleared from a steep hillside to grow crops. Explain why soil erosion increases.
- The leaves no longer intercept the rain, so it hits the soil directly and loosens it.
- The roots that bound the soil together are gone.
- On a steep slope the water runs off fast, with enough energy to carry the loose soil away.
Tips and tricks
- Give a chain, not a label. "Deforestation" earns one mark. "No roots to bind the soil, so rain washes it away" earns the next.
- Desertification means fertile land turning into desert. It does not mean a desert spreading by blowing sand.
It lands in your notebook with its questions as flashcards.
Soil erosion: causes and impacts: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What is soil erosion?
The fertile top layer is carried away.
Why does farming on a steep slope increase erosion?
Faster water has more energy.
What is silting?
It makes the river shallower.
How do tree roots reduce erosion?
Bound soil is harder to wash or blow away.
Which is a mass movement?
Landslides, rockslides and mudslides are all mass movements.
Why does silting make a river more likely to flood?Stretch
A channel with less room overflows sooner.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 8 marks. Write your answers on paper, then check them.
Soil erosion: causes and impacts
Cambridge IGCSE Environmental Management 0680 · 8 marks · papermunch.org
Name ______________________________ Date ______________
State two natural agents that erode soil.[2]
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Wind and water.
Explain why bare soil is easily eroded.[3]
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There are no leaves to shelter the soil from rain or to slow the wind. There are no roots to hold the soil together. Rain and wind can therefore remove the loose soil.
Describe how soil erosion can lead to famine.[3]
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The fertile topsoil is removed, with its nutrients. Crop yields fall. There is not enough food, which leads to malnutrition and then famine.
Answers: Soil erosion: causes and impacts
- 1. Wind and water.
- 2. There are no leaves to shelter the soil from rain or to slow the wind. There are no roots to hold the soil together. Rain and wind can therefore remove the loose soil.
- 3. The fertile topsoil is removed, with its nutrients. Crop yields fall. There is not enough food, which leads to malnutrition and then famine.