Healthy Aquifers
Overview:
Youth identify the geological components of a healthy aquifer by building an edible
model, defining vocabulary, and observing changes that can take place that affect the
world’s water supply.
Most rainwater leaves the area where it falls instead of infiltrating into the soil and
becoming part of the groundwater system. Rainwater harvesting can keep rainwater in
an area for a longer period of time by enabling more rainwater to soak into the ground.
Materials:
For each participant, pair, or small group:
• 2 clear plastic cups
• Straw
• Spoon
General Material List:
• 1 clear plastic cup to use as a demonstration model
• 1 straw to use as a demonstration model
• 3 different kinds of fruit, cut into different sizes and placed in separate bowls (could include
grapes, cantaloupe, honeydew melon, pineapple, apples, blueberries, strawberries, or other
choices)
• Serving spoon for each fruit type
• Bottle of 100% white grape juice (or as much as needed for
participants)
• 1 box of granola cereal
• Blue food coloring
• Small rocks to cover bottom of demonstration cup
• ¼ cup of gravel
• ¼ cup of sand
• 1 cup of water
• Plastic gloves for handling food (for those who will actually
handle the food)
• Photocopy of aquifer handout (included)
Duration:
25 minutes
Preparation:
•
•
•
Gather all necessary materials.
Add food coloring to the bottle of white grape juice for greater visibility.
Photocopy the needed number of aquifer handouts.
Activity Steps:
1. Ask participants to think about what they might find
underground. (Youth might name rocks, worms, roots, etc.)
2. Ask participants to think about an orange. Explain that if one
slices an orange in half, the inside looks very different than the
surface. In the same way, the earth looks very different
underneath the ground. This lesson is an exploration of what is
below people’s feet every day and how we “tap” into a hidden
resource for many of our daily needs.
3. Distribute copies of the aquifer handout and explain to
participants that there are different layers of different kinds of
rock under the ground. Some of the layers can hold water. An
area underground that can hold water is called an aquifer. In
some places aquifers can be like small lakes, like in caves, but
in most places, and throughout the arid Southwest, the water is
held in cracks in rocks, clay layers, and in between gravel and
sand particles.
4. Place small rocks in the bottom of the demonstration cup and ask youth if water could fill in the
spaces around the rocks.
5. Add a layer of gravel to the cup and ask if water could fit in the spaces between the gravel.
Note that the spaces are smaller.
6. Add a layer of sand to the cup and ask if water could fit in the spaces between the sand. Note
that the spaces are even smaller.
7. Slowly add water to the cup—first just enough to wet the sand. Mention that the water is like
rain, which, like snow, is a way that water gets down into the ground. Note that if there is not
very much rain and the water only stays close to the surface, it will evaporate without being
stored.
8. Slowly add more water to the cup so that it moves through the sand to the gravel layer. This is
an area that could store water because it is further underground. However, the spaces are
larger so water would move more quickly through the spaces.
9. Slowly add more water to the cup so that it fills the spaces between the rocks. Let the
participants see the water in the spaces.
10. Explain to youth that the bottom of the cup is a confining layer—it is solid so the water is trapped
and cannot soak further into the ground. Ask participants how water might get trapped
underground (caught in cracks in large rock formations, caught in clay layers, etc.)
11. Have participants look at their aquifer handouts and define the terms. Mention that the diagram
is a simplified picture. In reality, underground layers are rarely as even and clearly defined. In
many places it would be as if the demonstration cup were shaken and then filled with water—a
jumble of different materials all together.
12. Explain that much of the water used in many arid regions is groundwater—water stored in
aquifers. Ask participants how that water could be removed.
13. After participants provide answers, place a straw into the cup, through the layers to the bottom.
Explain that wells pull water from underground and bring it to people’s houses through pipes.
Sometimes that water is stored in storage tanks, especially in urban areas.
14. Slowly add more water until there is a layer of water on top of the sand. All the spaces have
been filled. Explain that the area is saturated. Because all the spaces have filled up, there is
nowhere for the water to go except to stay above ground. In lower places, this water becomes
surface water in a river, pond, or lake.
15. Explain that participants are going to create their own aquifers that will become healthy treats.
16. Distribute two cups to each participant; one will be for the aquifer and the other for grape juice.
17. Go through the steps of creating “underground” layers, using fruit of different sizes. Participants
should leave enough room at the top to add the yogurt and granola layers.
18. While participants are building their “aquifers,” fill their second cups with grape juice.
19. After discussing their fruit layers, participants slowly pour a little bit of grape juice into their cups
and watch how it begins to move through the top layer(s).
20. Participants keep adding grape juice slowly until the level reaches just below their top layer.
Have them look at the way the liquid filled in the spaces.
21. Remind them that the base of the cup is a confining layer but mention that confining layers can
be much closer to the surface. (For example, there is a layer of hard subsoil encrusted with
calcium-carbonate, called caliche, which can be found close to the surface in arid regions).
22. On top of the fruit layers, participants next add a layer of vanilla yogurt to represent soil. This
layer is just below the surface. Water infiltrates into the soil where it is used by plants but most
of the water evaporates rather than soaking in and becoming part of the groundwater system.
23. Participants add a top layer of granola which represents topsoil. This is the layer people walk
on. It is the most susceptible to evaporation and erosion.
24. Distribute straws.
25. Participants “pump” “groundwater” by sucking grape juice through their straws. They should do
this process slowly so that they can see the “water level” drop. As the liquid moves out of the
spaces, participants may see shifts and compression occur in the layers and the yogurt may
ooze down into the spaces.
26. Ask youth what might happen if all the “water” is pulled from their aquifers.
27. Ask youth to imagine what might happen if they were to pour a lot of grape juice onto their
aquifers. Get responses (runoff or flooding, for example). Participants can imagine this
scenario because the yogurt is not solid and if participants were to really pour the grape juice, it
would liquefy the yogurt and might be less appealing to eat later; however, some youth might
want to try it.
28. To demonstrate the recharging of an aquifer, participants can pour more grape juice on top of
their aquifers and watch the time it takes for the liquid to move through the layers. Explain that
most water that falls on a landscape during a rain event evaporates instead of soaking into the
ground. Groundwater is a limited resource.
29. Participants suck the grape juice out again, depleting the aquifer.
30. Explain to youth that just like the food in their models is healthy, it is critical to keep aquifers
healthy. Passive rainwater harvesting can help more water recharge the aquifer.
31. Distribute spoons so that participants can eat their healthy aquifers. Review vocabulary terms
and concepts.
Sources:
Developed by Alison Barrett, Instructional Specialist, Senior
The University of Arizona Cooperative Extension, Cochise County
450 S. Haskell Avenue
Willcox, AZ 85643-2790
(520) 384-3594
http://extension.arizona.edu/cochise
Diagram of surface water and groundwater adapted from U.S Geological Survey (USGS)
USGS web site: http://www.usgs.gov/
Diagram: http://ga.water.usgs.gov/edu/pictures/gwaquiferflow.gif
Diagram of soil layers adapted from Riverina Environmental Education Centre
Riverina Environmental Education Centre web site: http://www.reec.nsw.edu.au/
Diagram: http://www.reec.nsw.edu.au/k6/image/so3g.gif
Aquifer Handout
Groundwater fills the spaces between soil particles and fractured rock underground.
Underground layers of
clay, sand, gravel, and
rock that can store
water.
Aquifer model before adding water.
Aquifer
Aquifer model after adding water.
Bedrock