What is Erosion?

1. What is Erosion? Erosion is the process by which materials are removed from the surface and transported to another location. The sediments are carried away by gravity, water, wind or ice.

2. Erosion Erosion is caused by a number of different agents such as: water, gravity, wind and ice. Ice Erosion Gravity Erosion Wind Erosion Water Erosion

3. Erosion in our school When water flows over the earth’s surface, materials are transported from one area to another. These pictures highlight an erosion problem in our school’s playground. If left, the channels caused by the running water, will deepen and the dirt and bark will be washed away.

4. Erosion in our school By looking at the source of the problem, a solution such as a drain could redirect the water flow, stopping the channels which are currently forming each time it rains.

5. Erosion Solutions A dry dusty walkway in our school, was recently transformed by covering the area with pavers. This alteration reduces the risk of erosion or mud forming when it rains.

6. Erosion Investigation 0 Litres 1 Litre 2 Litres 3 Litres

7. Erosion Investigation 0 Litres 1 Litre 2 Litres In our erosion investigation, we found that once water was poured over the surface of the sand structure, it started to break down. We also found that each time we increased the amount of water, the more erosion occurred.

8. Erosion Investigation 3 Litres 3 litres of running water on the sandcastle had a devastating effect on its structural form. This picture clearly demonstrates how exposed materials are transported from one area to another when exposed to running water.

9. Ground Surface When water runs over compacted ground or harder soils such as clay, it speeds up the water flow, causing gullies to form, which over time turn into deep gullies. However, these soils are more durable against the wind. Sandy soils don’t bind together like clay, so they are less resistant to the wind.

10. Ground Surface Soil containing high levels of organic materials such as: mulch, fertiliser, manure or compost are often more resistant to erosion, because the organic materials combine to create a stronger, more stable soil structure. The extra layer prevents the rain from beating down hard directly on the soil, at the same time the water slowly soaks through the soil and enriches it.

11. Ground Surface Soil types, slope and ground cover all affect erosion in different ways. Water tends to flow over hard compacted soils, while it sinks into loose soils. Add some slope and the water flow speeds up, causing the looser soils to be washed away with the force generated. Water flowing on a gentle slope doesn’t have the ability to generate the same force, while water on flat land tends to pool.

12. Erosion Prevention This is an image of a young, fragile looking plant, growing just above the surface of the ground. What you don’t see, may surprise you!

13. Erosion Prevention Under the surface of the ground hides a complex root system, commonly found in ground cover such as grass, plants and shrubs. These roots help to provide stability to erosion prone areas by reinforcing the soil (holding in place).

14. Erosion Prevention Root Reinforcement Grass can prevent erosion problems, by permanently anchoring and reinforcing their roots into channels, slopes and other erosion prone areas.

15. Erosion Prevention Grass, shrubs, trees and general ground cover limit the possibility of erosion, by restricting water from building up speed when it runs over the land. Some of the water seeps into the ground instead of washing it away, which feeds and strengthens the vegetation’s root systems.

16. Erosion Prevention When stabilising a bank to prevent possible erosion, the size and steepness of the slope will affect how much vegetation is required to reinforce it. These images show how a small ditch only requires grass coverage, while the deeper river bank requires a lot more vegetation to properly stabilise the area.

17. Erosion Prevention • Rock Check Dam A check dam is a small barrier constructed of rocks or sandbags, which are placed across natural or man-made channels/drainage ditches. Check dams reduce channel erosion by reducing the speed at which water can flow through it. They also reduce the amount of sediment that would normally be washed away. This strategy is regularly used to control stormwater runoff.

18. Erosion Prevention Bio degradable erosion prevention mattress Soil erosion on steep banks/slopes by water and wind, affects both agriculture and the natural environment. Erosion control is the practice of preventing or controlling wind or water erosion in agriculture, land development and construction. This usually involves the creation of some sort of physical barrier, to absorb some of the energy of the wind or water that is causing the erosion.  Matting provides a protective barrier to soil until vegetation takes hold.

19. Erosion Prevention A windbreak (the row of trees) planted next to an agricultural field, acting as a shield against strong winds. This reduces the effects of wind erosion.

20. Erosion Prevention Some Key Points • Vegetation cover is vital to prevent erosion, as it protects the soil, reduces water flow and encourages water to soak into the soil. • Plant roots hold the soil in position and prevent it from being blown or washed away. • Plants/ground cover break the impact of a raindrop before it hits the soil, reducing the soil’s ability to erode. • Plants in wetlands and on the banks of rivers are important as they slow down the flow of the water and their roots bind the soil, preventing erosion.

21. Erosion Prevention Some Key Points • Wind erosion is of particular concern when the soil type present is loose, such as sand. Planting wind breaks to act as a barrier is one way of preventing wind erosion. • To stabilise erosion prone areas such as banks, matting can be used to hold the soil in place until vegetation takes hold. • To reduce erosion in drainage channels, small rock barriers can be placed throughout the channel to slow down the water flow, along with controlling the amount of sediment which is lost.