Groundwater Flow Model Demonstration Outline
Review Big Ideas:
1. Groundwater is in the pore spaces between sand grains, gravel and other soil
2. Water flows because gravity works below ground just like it works above
3. Groundwater is a part of the water cycle. Ground water and surface water are
4. We use ground water in our homes! Using a well installed with a pump and a
screen water companies pump, store and transport water for human use.
Materials: 1 groundwater flow models, 1 hand pumps with tubing attached to flask, 2
recharge bottles, 1 squirt bottles, 2 wooden stands, green dye, 1 grease pencil, paper
Introduce yourself: Who are you and what do you do? Why are you going to the
University of Arizona (if you are)?
Write your name, your teachers name, school and date on your paper
We have something called groundwater in Tucson. Has anyone ever heard of
groundwater? Does anyone know what it is? If not can anyone guess? Water under the
ground. What does groundwater look like? Have any of you ever seen what it looks like
underground? Draw what you’d imagine ground water looks like. Label your drawing
with the things that you know.
POROSITY TUBES (5 Minutes) This is review if they’ve done Investigation 4, Part 4.
Can water move through earth materials? How does water move through sand?
Gravel? Look at this porosity tube model. What do you see inside the tubes? Sand
and gravel. Which material do you think water will move through faster if we pour
water in through the top? Have students predict how long it will take for water to
move through each tube.
Have two students pour 250 ml of water in each tube and time the amount of time
that it takes for water to come out the bottom of each tube. Why does water move
faster through the gravel? Answer: Because the space between the particles is larger
than between the sand grains—we call the space “pore space”. It moves more
easily through the larger spaces.
Discussion: How do we find out what it looks like under the ground? Talk with your table
groups for 2 minutes about this. Ask one person in each group to share what their group
talked about. Answer: We drill a well and note the sediments that we go through as we
drill. So as we drill a well the earth material that we are drilling through comes out of the
hole. So if we the drill bit is at 100 feet and coarse grained sand is coming out of the
hole we know that there is coarse grained sand 100 feet below the ground surface. If
we put together many well logs across the Tucson basin we have a cross-section or a
picture of what it might look like underground.
This groundwater flow model represents what it might look like if you were able to sink
down in the ground 200 feet or so and you see across the entire basin. So from this side
of the model to this side represents miles and miles across the Tucson basin. And from
the ground surface down to the bottom represents hundreds of feet below the surface.
Explore the groundwater flow model. What do you thing it does? What is a model?
Explore and talk with your group about these questions.
What do you see in the model? There are two groundwater units represented here. Can
you tell me what one of them is made of? Gravel. What about the other groundwater
unit? Sand. Tell students that there are holes in each side of the model that allows
water to flow in to and out of the sand and gravel.
Where does groundwater come from in the earth system? The ground. How does it get
in to the ground? Rain or precipitation
Where does it rain most often around here? Up in the mountains
Have a student put a recharge bottle up on left side of model. This is our mountain rain
or mountain front recharge.
Open the valve on the right side of the model.
Have students study the ground water flow model to see if anything happens. As you
watch water bubbling out of the bottle and coming out of the outlet ask the question:
Where is the groundwater? (Point out again that there are holes in the column on the
left side of the model allowing water to enter). If they have a hard time with this
question point out that water in going in one side and coming out the other. How is it
getting there? It’s in the spaces between sand grains, gravel and other soil particles.
THIS IS A BIG IDEA!
Put green dye in observation wells B, C, and D. Make sure recharge bottle is still flowing
and that the valve is still open. Have students again study the groundwater flow model
to see what happens. What is happening to the green dye? It’s moving. Which
direction? To the right. Why? Gravity works! - water flows from up high to low. If they
don’t get this, drop a pen and ask why that pen dropped. Gravity works below ground
just like it works above ground. THIS IS A BIG IDEA!
What will groundwater move fastest through sand or gravel? Point to the porosity tubes.
Why? Because the pore space is greater.
So if rain travels through rock in the mountains and goes in to the groundwater. And
then goes miles and miles through the ground. Where does it come out? In the surface
water. Ground water in some areas is connected to surface water. Have you seen a
flowing river before? Most of those rivers are connected to ground water. Is ground
water a part of the water cycle? It is it can move from the ground water to the surface
water. Can water move from the surface water to the ground water? Fill one of the
surface features with water and have students observe what happens. Have a group
describe what happened. Water moved down in to the ground water. The
groundwater is a part of the water cycle. THIS IS A BIG IDEA!
Why do we care about groundwater? We use ground water in our homes! THIS IS A BIG
IDEA! How is groundwater withdrawn from the ground? Using a well installed with a
pump and a screen to keep soil from being drawn in with the water. There are two kinds
of wells represented here. There are two pumping wells. These are the wells with the
rectangular box at the end. That is a well screen and keeps the sand from coming into
the well when we pump it. With grease pencils, we will label pumping wells 1 and 2.
There are also wells called observation wells; they are wells that we use to look at the
water level and take hand samples.
Pump well number 1, put more green dye in well D and have a few volunteers come up
one by one and pump the well. What happens to the green dye? Moves into the well.
What happens to the green dye in well D? It comes back to the well against gravity.
Pump wells until dye is cleaned up. Answer questions that students have about the
models or groundwater.
So ground water is one source of water for Tucson. Does anyone know another source
of water for Tucson? We get Colorado River water through the Central Arizona Project
(CAP) canal. The water from the Colorado River on the western side of our state moves
in a canal 336 miles across the state to Tucson where we store it in the ground!
Review Big Ideas:
Groundwater is in the pore spaces between sand grains, gravel and other soil
Water flows because gravity works below ground just like it works above ground.
Groundwater is a part of the water cycle. Ground water and surface water are
We use ground water in our homes! Using a well installed with a pump and a
screen water companies pump, store and transport water for human use.
Write your name, your teachers name, school and date on your paper (this is not a test!)
What does groundwater look like? Draw what you think the ground water system looks
like. Label your drawing with the things that you know.
Preparation for Wetlands fieldtrip (if there is time):
You will be coming to the Sweetwater Wetlands on _______ to engage in more hands
on water lessons. You’ll have a lot of fun with other Americorps members and
University of Arizona students. Does anyone know what a wetland is? A place that is
wet for at least part of the year. The Sweetwater Wetland is wet all of the year but it
is a human created wetland that was created for a purpose. Can anyone guess
what that purpose is? Wetlands can help to clean water.
In the case of Sweetwater Wetland we send water from the wastewater treatment
plant to the wetland. Where does that water that comes in to the wastewater
treatment system come from? It’s the waste from our homes (what goes down the
drain and what is flushed down the toilets). At the wetlands you will learn how our
wastewater is filtered and that the waste that is caught on the filter goes to the
wetland, where the wetland helps to clean it.
Did you know that we had a wetland area in our city? You'll get to go there soon
and participate with University of Arizona students in some really fun learning
activities. And we hope when you’re older you’ll come learn at the University of