Soil Erosion by Wind

Time - 25minutes

Student Outcomes
None for this teacher demonstration

Materials

• pictures of wind erosion
• aluminum - disposable baking pan (turkey size) or a cookie sheet
• a variable-speed blow dryer
• plastic drop cloth or sheet
• sand to cover base of pan
• small cedar or juniper branches
• about 40 questions covering all activities

Focus

"Is water the only problem concerning soil erosion?" "What else can cause soil erosion?" (wind, people, land slippage)

"Let's look at wind erosion."

"We will see that wind plays a role in soil erosion. Some soils are more prone to wind erosion than others. Most wind erosion occurs in areas of high prevailing wind speeds and low-annual rainfall. Soils have a smooth surface and are composed of particles that are easily moved by wind."

"What else would cause a lot of wind erosion?" (limited vegetation cover)

"Where do you think wind erosion would be of most concern?" (Somewhere where there is not a lot of vegetation: the plains, prairies. Texas has greatest land area subject to wind erosion.)

Procedure - Teacher Demonstration

"Let's do an activity to see just how wind erosion occurs."

1. Place the drop cloth on the floor with dryer at one end. Locate the blow dryer 6 to 24 inches away (dependent upon the size of the dryer) so the direction of airflow is over the drop cloth.
2. Turn on dryer at varying speeds. "What can we do to help save this soil from the wind? What do I have out for you that we could add to our pan of soil that might keep the soil from moving?" (small cedar or juniper branches) Return sand to pan. Let students place the twigs and branches in various ways to see where they protect the soil the most. Again, turn the fan on.
3. "What happened this time when the wind blew over the soil. We see again that vegetation helps prevent soil erosion. We also see that a great way to control wind erosion is to plant a cover crop or windbreak that decreases the speed of the wind at the soil surface. What are windbreaks? They can be rows of evergreen trees planted perpendicular to the wind, narrow bands of tall grasses, or grasses planted in the fields instead of row crops."
4. "What other things can cause erosion? (land slippage and people)

"Land slippage refers to blocks of saturated soil moving down slopes in response to gravity similar to an avalanche usually seen as a cave-in of a cliff or bluff that overhangs a river or stream. It can also be seen as landslides or mud slides along steep road embankments (southern California)."

"People also cause erosion. How does this happen?" (people taking short cuts through lawns, shrubs, or down banks; people scuffling feet under playground equipment; people playing in one spot continuously; a baseball field, etc.) "Can you think of any others? Has anyone seen any of these? What can we do to prevent this people-caused erosion?"