Lab_Groundwater
GSCI 121 Our Geologic Environment Lab
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This lab will help you familiarize yourself with the following basics of water resources:
-What is groundwater?
-How does groundwater move?
-What happens when contamination is introduced to a groundwater system?
Part 1: Groundwater Modeling
Model #1 – Plain ol’ pumping:
1. Saturate the gravel: add water until it is almost at the top of the gravel.
a) Can you see the water table? ___________
b) If you can’t see the water table, add a little more water.
c) Predict what will happen in the model if the water is sucked out through the pump.
Prediction: _____________________________________________
2. Pumping the aquifer.
a) Stick the pump into your aquifer. Make it deep enough so that you can supply a
small village with water.
b) Start pumping out water with the pump.
c) Sketch below and describe in words what you observed after pumping out some of
the water.
Side effects of pumping:
______________________________
______________________________
______________________________
______________________________
BEFORE
PUMPING
AFTER
PUMPING
3. When this sort of pumping occurs a cone of depression forms. Why didn’t this happen in
your aquifer?
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Lab_Groundwater
GSCI 121 Our Geologic Environment Lab
Model #2 – Contamination due to an injection well:
4. Inject a contaminant.
a) Insert a straw into your aquifer. Place the straw on the other side of your aquifer far
from your pump. Place it so that you can see it through the side of the bottle.
b) Inject contaminant (food coloring) into the injection well (straw).
c) Describe your observations after injection occurs:
Observations: _____________________________________________
________________________________________________________
5. Begin pumping water again. Describe what you observe after pumping water:
Observations: _____________________________________________
________________________________________________________
Model #3 – Landfills:
6. Create a landfill. This landfill follows state regulations and has a lining.
a) Excavate a small pit in your surface (don’t penetrate the water table though) – do
this on the edge of your bottle so that you can see if there is any downward
movement of contaminants.
b) Place a two-inch square plastic sheet on the surface.
c) Add one or two drops of food coloring to the center of the plastic sheet.
d) Let it rain just a little (use your squirt bottle), and describe your observations:
Observations: _____________________________________________
________________________________________________________
7. Create another landfill…this time break the law! To do this, place your contaminants down
without a liner.
a) Make a small depression in the surface – again do this on the edge of your bottle to
help you see if there is any downward movement of contaminants.
b) Add 1-2 drops of food coloring into the center of the depression.
c) Let it rain just a little again. Describe your observations after rain occurs:
Observations: _____________________________________________
________________________________________________________
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Lab_Groundwater
GSCI 121 Our Geologic Environment Lab
Synthesis:
8. What happens to the zone of saturation when a pumping well removes water from below
the water table?
9. What happens when an injection well introduces a contaminant to the zone of saturation?
What would change if the contaminant was only injected into the zone of aeration?
10. What might happen when a pumping well is near an injection well?
11. Do you think industry has a right to inject industrial wastes without regulation? Defend
your position with at least three good reasons:
12. How might a community go about cleaning up contaminated groundwater?
Part 2: Mapping Groundwater and Gradient, Case study: Woburn, MA
**complete parts 1 and 2 before completing this section**
Groundwater and contaminants move differently depending if water wells are pumping. Let’s see
how the movement of groundwater and contaminants changes depending on the pumping activity.
SCENARIO 1: No wells active. (Figure 1)
13. Draw in the contour lines for Figure 1 and label them. These lines represent the surface of
the water table. Use a 10-foot contour interval. This is just like drawing topographic
contour lines – each line represents a single elevation.
GRADIENT:
Ø Water (and contaminants) flow from areas of high potential energy to areas of low
potential energy (…high elevation to low elevation). The steepness of that energy
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Lab_Groundwater
GSCI 121 Our Geologic Environment Lab
change is called gradient. Water (and contaminants) will follow a path with the
steepest gradient.
Ø Gradient is calculated with the following equation.
% gradient = 100 x Change in elevation from point A to point B
Distance between point A and B
To find gradient, look at the elevation for points A and B on the map and subtract to find the
change in elevation between those two points. Then, measure with a ruler the distance between the
two points. You will have to convert measured distance to a map distance using the scale on the
map. Here are two examples of gradients…which has a steeper gradient?
If you said the example on the right has a steeper
gradient, you are correct. This is because it has a
greater change in elevation from top to bottom
over a shorter distance.
ALSO! Elevation change and distance must have the same units…that way when you divide,
units cancel!
14. Using Figure 1, calculate the gradient from the 70* (by WR Grace) to:
a. 56*
b. 55*
c. Which of the above gradients is steeper?
d. Based on the above, explain why flow lines must cross contour lines at right angles.
CONTAMINANT MOVEMENT:
15. Assume that Unifirst, WR Grace, and Beatrice are illegally dumping contaminants onto
their properties and these contaminants leak into the zone of saturation. Draw flow lines on
Figure 1 showing how contaminants will move from these three point sources.
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Lab_Groundwater
GSCI 121 Our Geologic Environment Lab
SCENARIO 2: Active pumping at wells H and G. (Figure 2)
16. Look on Figure 2 and find wells H and G. These wells are now pumping; draw in the
contour lines on Figure 2 and label them. Use a 10-foot contour interval.
CONTAMINANT MOVEMENT:
17. Draw flow lines showing how contaminants will move from the three point sources,
Unifirst, WR Grace, and Beatrice.
Synthesis:
18. Describe the changes in the water table contour map between scenario 1 and scenario 2.
19. Describe the changes in the groundwater flow direction (and contaminant movement)
between scenario 1 and scenario 2.
20. Where would you place a well for drinking water extraction that would be contaminant free
regardless of whether wells H and G are actively pumping or not? Explain your reasoning.
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Lab_Groundwater
GSCI 121 Our Geologic Environment Lab
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Lab_Groundwater
GSCI 121 Our Geologic Environment Lab
Part 3: Water and Land Use Change
Direct your web browser to:
http://earthshots.usgs.gov/
“Earthshots introduces remote sensing by showing examples of environmental change from around
the world. Explore this site to see how satellite imagery is used to track change over time.”
**Basic information on how to read these images is found while perusing this website.**
21. Click the “About Earthshots” box on the left side of the screen. Clicking on the five tabs to
the right gives information on the images. Click the segment “What the Colors Mean.”
Images are made up of what three color combinations? ________ ________ ________
These colors are combined in bands, such as 4,3,2 or 3,2,1 or 7,4,2 to produce natural color,
false color, or color-infrared images. Move your cursor over the images starting with Mt.
St. Helens, WA; click the arrow on the right of the image to page through the rest of the
images – be sure to read the image captions so you can answer the questions below!
a) Scroll through the images to find the image of M. Vernon, Washington; it is a
predominantly red and blue Landsat satellite image. The band used to color this
image is a combination called 4,3,2. What type of image does it produce (in
parentheses)?
b) What do you think the red color in this photo represents?
c) And the light blue color?
d) Click the to the next photo of Mt. Vernon, Washington; mostly a green and tan
image. The band combination is 3,2,1…what type of image does it produce?
22. Click on the “Table of Contents” box on the left to go back to the home screen. From there,
click the Agriculture link and select Garden City, Kansas. This location can also be
selected by clicking the red indicator over Garden City, Kansas on the map. Read the text
on the right of the screen to answer the questions below.
a) What does red on this map indicate?
b) What do the light-colored areas indicate?
23. Why are the agricultural areas (farms) in Garden City generally round?
24. What is the source of the water used for irrigation in Garden City?
25. How has the total number of circles changed between 1972 and 2011 (scroll through the
images)?
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Lab_Groundwater
GSCI 121 Our Geologic Environment Lab
26. Based upon your answers for questions 14 - 17, what do you learn about the use of water in
Garden City?
27. The article mentions the Ogallala Aquifer. An aquifer is an underground geologic
formation (layers of rock) that contains and transmits large quantities of groundwater. The
Ogallala Aquifer stretches underground from Texas to the Dakotas! How will the land
and groundwater use changes in Garden City farming affect this aquifer?
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