of Economic Geology
1: Aquifer Model in a Tank
simple model is intended for student inquiry into ground-water systems.
Have your students try things (within the context of the model), observe
what happens, and record and interpret their observations. After this
inquiry they will better understand aquifers and the issues of climate,
spring flow, environmental protection, and water use that are so hotly
debated in Austin and elsewhere in Texas.
model can be productively used in the context of process TEKS (4.3) and
(5.3) to "represent the natural world using models and identify their
limitations" and concept TEKS (5.5) describing groundwater as part of
the water cycle; (5.11) renewable resources, (6.14) groundwater and surface
- Vadose zone
- Water table
- PVC pipe
with holes drilled to serve as screen interval. Screen interval can
be at the bottom or about 10 cm from the bottom end of the pipe. Pipe
2.5 cm in diameter and 38 cm long
- Plug to fit
the bottom of the PVC pipe
- Several liquid-soap
- Plastic tubing
to extend the tubing on the soap pump (the end of the plastic pipe
should reach the screen interval in the PVC pipe.)
- Scoops to
handle gravel and sand
- 80 lbs gravel
- 20 lbs sand
- Binder clips
to hold hoses to tank and buckets
- Squirt bottle
or rain maker (container with holes punched in bottom)
- Several graduated
(1- or 2-liter) pitchers to measure water
- Dishpan or
1- to 2-gallon tub for ocean
- Plastic tubing
for siphon (river)
to look down well
- 1 small plastic
container (yogurt or butter tub) with holes punched in the bottom
for spring swimming pool
for Lab 1: Aquifer Model in a Tank
the well casing out of the PVC pipe:
- Using a nail
or drill, make numerous holes in the pipe. Make one well casing with
holes in the bottom 2 cm of the pipe and another with holes about
8 to 10 cm from the bottom of the pipe. These are the screen intervals,
the parts of the well that the water from the aquifer goes through.
In the real world, we normally drill a well until we hit the water
table and then set the screen interval at the top of the aquifer.
In our model, we push the well casing to the bottom of the aquifer
to keep it from wobbling during our experiment, and the 10-cm screen
interval will be near the top of the aquifer.
- Cap the bottom
of the PVC pipe well casing.
- Making the
pump: Extend the tube on the soap pump by attaching plastic tubing
to the bottom of it, such that it reaches from the top of the PVC
pipe to the screen interval (holes made in the pipe).
- Put gravel
in the tank. It will serve as the first laid-down layer of the aquifer.
Make the layer approximately 6 cm thick.
- Put a 1-cm
sand layer on top of the gravel layer. It will serve as another layer
of the aquifer. You can experiment with various sand thicknesses.
- Lay another
layer, 5 to 12 cm thick, of gravel on top of the sand. Make it hilly.
Total thickness of the fill in the tank should be 12 to 17 cm.
- Make a spring
by digging into the fill and placing there a plastic container with
holes in the bottom.
- If you like,
decorate the land with vehicles or a house.
the aquifer. Slowly pour/squirt a measured volume of water onto the
land. Start with 3 L of water. Observe what happens and record this
event on the data sheet.
- Label aquifer,
vadose zone, water table, spring, and well.
- Measure the
water level with respect to a datum (the bottom of the tank); record
on data sheet.
- Start spring
- Make a siphon.
This is going to be the "river" to transfer the water from the spring
to the "ocean."
- Cut 3 ft
of plastic tubing.
- Fill the
tubing with water; make sure there are no bubbles. You can do this
in a tub full of water or at tap.
- Use your
thumbs to seal both ends of the pipe so that there are no air bubbles
- Put one end
of the pipe into the spring and the other into the ocean tub, which
must be at a lower level than the spring. Release both thumbs from
the ends of the pipe. You will see the water coming into the tub from
the spring. Use the squirt bulb to restart flow if it stops.
- Drill the
well (push PVC pipe down into the aquifer). Start with the well screened
at 10 cm.
- Pump the
well and collect and measurethe water in a cup. See what happens.
- Record what
happens on your data sheet. Be sure to fill in all the columns each
time an event occurs.
the aquifer by slowly raining on the surface. Be sure to measure the
volume of water that you add.
with the variables. Stop the rain and have a drought. Try recharge
events of different magnitudes (a sprinkle and a flood). Install the
deeper well and pump the wells hard. Be sure to measure and record
volume of water added and removed and the effect of each experiment.
- Analyze the
- Analyze the
Sheet for Lab 1: Aquifer Model in a Tank
Model in a Tank: Analyze the Data Qualitatively
and label the parts of the aquifer using the vocabulary.
with arrows how the water moves in the system.
happens to the system when it rains?
happens to the system when it stops raining (during a drought)?
does what we see in the model matter in the real world?
1: Aquifer Model in a Tank: Analyze the Data Quantitatively
your data sheet, circle all the volumes of water that you added as rain
(recharge), and then add them together. Total recharge = ____ L
your data sheet, box all the volumes of water that you pumped out (well
discharge), and then add them together. Well discharge = _____L
the volume of water that flowed out of the spring, down the river and
to the ocean. Spring discharge = _______L
a histogram of the water budget of your aquifer:
2: Contaminants in a Tank, Cleaning up Spills
lab is a continuation of lab 1. In that lab we focused on water resources,
that is the quantity of water in the system and how it works as a cycle.
In this activity we look at water quality and how human activities can
make an impact on surface and ground water.
addition to the set-up from lab 1, make the following analogs for contaminants:
to 5 mL yellow food coloring in 100 mL water
spill, water soluble
pesticides, and herbicides
to 5 mL green food coloring in 100 mL sugar
into solution by rain
in water, less dense than water
from landfill and disposal sites, sewage
mL red food coloring, 100 mL cornstarch, 100 mL elbow macaroni.
Add cooking flavor of your choice to add garbage "aroma."
soluble, leached from disposal sites by rain
how each contaminant enters the environment.
your ground-water system to running, with spring flow, pumpage, and recharge.
Experiment with contaminating the environment to simulate various contamination
events that have happened or might happen and observe what does happen.
up the model, recycling the materials.
2: Contaminants in a Tank: Observations and Conclusions
- How does
the contaminant get into the groundwater?
- How does
it come to the surface to affect people and animals?
- What could
the people who live in the model do to clean up their contaminated
- What conclusions
did you come to from observing the model that you can tell people?
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