Preventing erosion
Compare multiple solutions designed to slow or prevent wind or water from changing the shape of the land
What a learner can do afterwards
- Describe how wind and water can change the shape of land (erosion)
- Compare at least two design solutions for reducing erosion (e.g. retaining walls, plants, windbreaks)
- Evaluate which solution works best based on evidence from tests or observations
1 · Read
Erosion moves rock pieces or soil. Waves carry sand away, rain washes soil downhill, and wind blows loose soil away. This can happen slowly or quickly, such as during a storm.
Plant roots help hold soil together. A retaining wall holds soil back on a slope. A wall facing waves may reduce water reaching sand behind it. A windbreak, such as trees or a fence, slows wind near the soil. Because these designs work differently, compare their results for the place you want to protect.
Depth readings describe marked spots, not all the soil in a model. A smaller drop means the surface lowered less at that spot. To measure all the soil washed away, collect it all. An adult dries and weighs it in grams (g). In a fair test, losing less soil means better protection in those conditions.
Example fair test: no cover 14 g lost, wall 10 g, plants 8 g. Plants lost least.
In a rain test, water carries soil away from two matching models. At marked spots, the soil surface drops 7 cm without cover and 4 cm with cover. To find how much less it dropped with cover, subtract: 7 minus 4 is 3 cm.
For a fair test, use model hills with the same soil, slope and starting depth. Give them equal water for equal time. Change only the protection being compared. Repeat the test. Ask an adult to help with models. Real walls and changes to land need adult planning.
Plants, walls and windbreaks can reduce erosion in different ways. Fair tests help compare designs for a particular place.
The lesson, questions and flashcards were written for this dataset.
The readings were written for this dataset. The linked weathering and erosion video is by Khan Academy.
More to read
Roots and walls
Roots spread through soil and help hold it together. A retaining wall holds soil back on a slope. These are different ways to reduce soil movement.
People check the soil, slope and water before choosing a design. Real walls need adult planning. Small classroom models let us compare designs without changing a real hillside.
Test a model safely
Ask an adult to help set up small soil trays inside a larger catch tray. Keep spilled water contained.
Use matching soil hills and equal water when comparing protection. Record what moves and repeat the test. A classroom result is evidence about that model. It is not a plan for building walls or digging channels on real land.
Covering bare soil
Bare soil is exposed to rain and wind. Plant cover can protect its surface, while roots help hold it together. Straw or wood chips can also cover soil.
Compare covered and uncovered model soil using equal water. Collect the soil washed away from each. A smaller loss shows better protection in that test, not a winner for every place.
Different places need different designs
Wind can carry loose soil from a field. Rows of trees can slow wind near the ground.
Rainwater can carry soil down a hill. Rows across a hillside can slow flowing water. Some farms use flat steps called terraces. Farmers choose methods for their land and conditions. No one method stops all erosion.
Look for moving material
Sand blowing across a path shows material moving. Rainwater carrying soil out of a small channel is another example of erosion.
Compare the same place before and after rain. Record what changed and how long it took. Observe with an adult from a safe place, away from flowing water, steep banks and cliffs.
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2 · Watch
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Where it sits
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Where this leads
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