Where Does
the Water Go?
Part II
Rainfall/Erosion Simulator
Where
Does the Water Go?
Runoff
Runoff
Use this as a demonstration to show erosion and how streams, rivers and lakes can become filled with sediment. Also, agricultural practices such as contour plowing and terracing can be demonstrated.
Procedure:
| 1. | At one end of each pan bend the edge so that it forms a spout for runoff water to drain. |
| 2. | Box 1 - fill 2" from the top
with soil and lay sod on top. Box 2 - fill 1" from top with soil and cover generously with grass clippings. Box 3 - fill 1" from top with soil and leave bare. |
| 3. | Prop one end of each box 2-3" above the table. Hang the lower edge off the edge off the table. |
| 4. |
Predict which box will be the most likely to suffer erosion. |
| 5. | Predict which box will have the least runoff. |
| 6. | Predict which jar will have the cleanest runoff water.. |
| 7. | Place a jar under the spout below each box. |
| 8. | Pour a measured amount of water in sprinkling can and use it to "make it rain" on one box at a time. Continue to add water in measured amounts until water runs into jar. |
| 9. | Repeat for each box. |
| 10. | Have students answer questions based on their observations. |
Additional Demonstration:
|
1.
|
On the pan with the bare soil, construct ridges running across the pan, to simulate contour plowing. Repeat the sprinkling demonstration. |
|
2.
|
Using the same pan, construct two higher ridges of soil to simulate terraces. Place one about 3" from the top edge of the pan and the other about 3" from the bottom edge of the pan. Repeat the sprinkling demonstration. |
Questions for discussion:
| 1. | Which box had the most runoff? |
| 2. | Which box had the least runoff? |
| 3. | Which box had the cleanest runoff? Why? |
| 4. | What happens to soil in a farmer's field when water runs off too quickly? |
| 5. | What effect might this have on the soil that remains in the field? |
| 6. | What effect might this have on the crops the farmer plants in this field? |
| 7. | If you were a farmer, what could you do to help protect your soil from erosion? |
Diagram of how Rainfall Simulator should be set up.
Additional Demonstrations to show how
contour plowing helps control erosion.
contour plowing helps control erosion.
