Adapted with permission.by Earth Science Information Partners.
After rain falls on relatively high land, it moves downwards into drainage areas called watersheds. You will create a model of a watershed by spraying rain on a plastic cover representing Earth’s surface. By watching how it flows, you can identify drainage divides and learn about the movement of water.
• Large aluminum roasting pan
• 6–10 pages of newspaper
• Masking tape
• A sheet cut from white plastic trash bag slightly larger than the pan
• Spray bottle
• Blue food coloring
• Paper towels
• 2 colors of permanent markers
• Blocks or a notebook to lift one end of the tray
• Computer with internet access
- Crumble several pieces of newspaper into balls and rolls of different sizes and shapes. Place them into your roasting pan. Use tape to keep them in place.
- Smooth out any wrinkles in your plastic sheet.
- Raise one end of the pan on blocks or a notebook, then cover the entire pan and its contents with the plastic. Gently press the plastic down around the crumpled paper balls. Leave the excess plastic around the outside of the box.
- The plastic cover represents Earth’s surface. The lumps represent mountains and hills, and the areas between them represent valleys. Use your imagination to visualize your model as a portion of Earth’s surface.
- Fill your spray bottle with water and add a few drops of blue food coloring for visibility. Spray just enough rain to see how the water interacts with your model landscape.
Look for these features in your model:
• Streams or rivers — linear flows of water running downhill.
• Ponds or lakes — areas where water pools in low areas.
• Drainage divides — imaginary lines where the “rain” goes to one side or another.
7. When you think you can predict the locations of streams and drainage divides on a model landscape, wipe your plastic dry and set up the model again.
Draw your predictions for the locations of streams and divides directly on the plastic.
8. Pair up with another lab group and test each groups’ predictions about the location of their streams and divides.
9. Discuss the results and your ideas for improving the model.
10. Examine the pattern of the flow of water in your watershed using a map (https://water.usgs.gov/wsc/map_index.html).
Discuss how well the model represents reality for the concept of watersheds and drainage divides.
This lab is adapted from a larger collection provided by EarthLabs. View a teacher guide and access to other labs and modules (https://serc.carleton.edu/earthlabs/drought/2.html). The activity comes from TERC, an Earth Science Information Partners (ESIP) Type III partner, and was adapted by the ESIP Education Committee which promotes the use of Earth science data in education and offers “Out2Lunch” webinars (https://wiki.esipfed.org/Education/Out2Lunch) highlighting Earth science tools and resources for educators.