A-2: Create Your Own Watershed

Appendix 2. Create Your Own Watershed

A three-dimensional model of a watershed is one of the best ways to demonstrate the watershed concept to your students. With a three-dimensional model, you can demonstrate how water runs from peaks and ridges, to low points such as valleys, wetlands and other depressions. In addition, with the use of a few household kitchen items, such as cool-aid and cocoa you can demonstrate how pesticides and sediment are washed off the earth’s surface during rain events and into our lakes, rivers and oceans.

Materials:

spray bottle with blue-colored water
a large aluminum roasting pan
numerous rocks of various sizes
several pieces of white scrap paper or newspaper
one kitchen-size white trash bag
Cocoa and cool-aid mix

Procedure:

Wrap the rocks in newspaper and place on the bottom of the roasting pan to create an uneven surface (the topography of your watershed).
Cover the rocks with the white trash bag, being careful to tuck the edges under the rocks (use a few rocks on top to hold the trash bag in place).
Ask the students where they think water that falls on this watershed will flow
Spray the model with the blue-colored water until water begins to run-off the higher points and pool in the lower areas (depressions).
To show how pollutants are washed off the land surface, sprinkle cocoa and cool-aid in key locations (where erosion or pesticide use might occur) - then spray the model again until the pollutants run-off into the depressions.

This activity can be done as a class, or in smaller groups. If small groups create their own watersheds, have the groups compare their results at the end.

To make a permanent model, use the above supplies, but substitute paper-mache material for the white trash bag. Once the paper-mache has dried thoroughly, paint the model with white water-proof paint. The model can now be re-used with numerous classes.