DAY 2 Get the Ground Water Picture
AIM: What are the different parts of a ground water system?
AIM: How does water move through the different layers of the ground system?
AIM: How can different types of land uses potentially contaminate ground water?
Background Information: Ground water is one of Earth’s most
valuable natural resources. The water stored in the pores, cracks and
openings of subsurface rock material is ground water. Wells dug by
hand or machine have been used throughout history to retrieve water
from the ground. Scientists use the word AQUIFER to describe an
underground formation that is capable of storing and transmitting
water.
Questions
1. What is an aquifer?
Aquifers come in all shapes and sizes. Some aquifers may cover
hundreds of square miles and be hundreds of feet thick, while others
may only cover a few square miles and be a few feet thick. Water
quality and quantity vary from aquifer to aquifer and sometimes vary
within the same system. Some aquifers can yield millions of gallons of
water per day and maintain water levels, while others may only be able
to produce small amounts of water each day. In some areas wells
might have to be drilled thousands of feet to reach usable water, while
in other areas water can be located only a few feet down. One site
might contain several aquifers located at different depths, and another
site might yield little or no ground water.
2. How much water do aquifers hold?
The age of ground water varies from aquifer to aquifer. For example,
an unconfined surface aquifer might hold water that is only a few days,
weeks, or months old. On the other hand, a deep aquifer that is covered
by one or more impervious (water can’t get through it) layers may
contain water that is hundreds or even thousands of years old.
3. How old is the water in one aquifer?
The rate of movement of ground water varies based on the rock
material in the formation through which the water is moving. After
water percolates (goes through) down to the water table, it becomes
ground water and starts to move slowly down gradient. Pressure comes
from the weight of overlying water and earth materials. Ground water
moves toward areas of least resistance.
HYDROGEOLOGISTS, scientists who study ground water, know
that the in order to really learn how the ground water system works,
they must drill wells. When this well is drilled, the data collected
becomes part of the well’s WELL LOG. The driller’s record provides
valuable information for determining ground water availability,
movement, quantity, and quality.
If hazardous waste, chemicals, heavy metals, oil, etc. collect on the
surface of the gorund, rain or runoff percolating into the soil can carry
these substances into ground water. That is why when hydrogeologists
drill the wells, they consider the land use practices in the watershed
areas.
4. Where does ground water tend to
move towards?
5. Who are hydrogeologists?
6. What is a well log?
DAY 2 Get the Ground Water Picture
WARM-UP
Directions: Choose ONE of the following and provide you answer in the space below.
1. Draw a picture representing what you think underground water system looks like.
2. Write a brief description of what you think happens to water after it seeps into the ground.
ACTIVITY 1: AIM: What are the different parts of a ground water system?
MATERIALS
12 plastic cups
Gravel
Sand
Clay
Magnifying Lens
PROCEDURE
1. Place gravel, sand and clay in separate plastic cups.
2. Closely look at each container with the magnifying lens.
3. Pour water into each container to demonstrate how water moves through underground rock formations.
4. Observe what happens and write down you observations.
DAY 2 Get the Ground Water Picture
DISCUSSION QUESTIONS
1. Which container emptied the fastest?
2. Which container emptied the slowest?
3. How would the different materials influence water movement in natural systems?
ACTIVITY II: AIM: How does water move through the different layers of the ground system?
DEMONSTRATION
Prior to beginning this part of the lab, please watch the demonstration.
MATERIALS
Strip of white paper
Well Log Data Chart
Ground Water Student Page
PROCEDURE
1. The white paper represents the length of a well that has been dug.
2. The number on your white strip corresponds to the WELL NO. written on the Well Log Data Chart.
3. Use the data provided on the Well Log Data Chart for you number and transfer the information to the strip
of paper. (as during the demonstration)
4. Divide your strip into 12 inches (as doing the demonstration)
5. Mark the level of the water table by drawing a double-line at the appropriate point (ex. 2 means 2” from the
top).
6. Complete the drawing by coloring light blue the area between the water table and the top of the clay layer.
Also color the gravel layer with a different color.
7. Make sure to note the land use existing above the well site.
DISCUSSION QUESTIONS
1. The horizontal scale of the cross section is 1 inch= 1 mile. The vertical scale is 1 inch=50feet. How many
miles are horizontally represented in the cross section? How many feet are vertically represented in the cross
section?
DAY 2 Get the Ground Water Picture
2. How many feet below the surface is the water table?
3. Imagine a drop of water falling on the surface above your well. What pollutants might this drop of water
pick up as it filters into the ground?
4. Describe the drop’s movement down the column. Through which layers would it move the fastest? The
slowest?
5. At which layer might the drop’s movement be restricted? If clay will stop them the most, how did the water
get to a layer below the clay?
ACTIVITY III: AIM: How can different types of land uses potentially contaminate ground water?
PROCEDURE
1. Place your log number in order, and tape it to the poster in the front of the classroom.
2. Using the Ground Water Student Page and the definitions in the WORD BOX please complete the
following steps.
WORD BOX
WATER TABLE: the top of an unconfined aquifer.
CONFINED AQUIFER: an aquifer that is bounded above and below by nonpermeable layers that transmit water
significantly more slowly than the aquifer. Also called artesian aquifer.
UNCONFINED AQUIFER: An aquifer in which the upper boundary is the top of the water table.
PERMEABLE LAYER: Portion of aquifer that contains porous rock materials that allow water to penetrate freely.
IMPERMEABLE LAYER: Portion of aquifer that contains rock material that does not allow water to penetrate;
often forms the base of unconfined aquifers and the boundaries for confined aquifers.
ZONE OF SATURATION: the part of a water-bearing formation in which all spaces (between soil particles in
rock structures) are filled with water.
ZONE OF AERATION: Portion of unconfined aquifer above the water table where the pore spaces among soil
particles and rock formations are filled with air.
DAY 2 Get the Ground Water Picture
3. Locate all the parts in the WORD BOX on the Well Log Ground Water Chart (Cross Section).
4. Make sure at this point to CALL MS. KASIA to confirm you have located the parts correctly. (check)_____
DISCUSSION QUESTIONS
1. What direction is the water moving in the unconfined aquifer?
2. What are water sources for the unconfined aquifer?
3. How long would it take the water in the sandstone formation to move from WELL#1 to WELL#15?
(NOTE: Assume the water moves at a constant rate and flows at 100 feet per day [1 mile = 5280feet]).
4. Imagine a drop of water falling on the surface above your well. What pollutants might this drop of water
pick up as it filters into the ground?
5. Refer to Cone of Depression diagram. The cone of depression results from water being drawn up the well.
Locate the cone of depression on the Well Log Ground Water Chart (Cross Section).
6. Refer to the Ground Water System (Simiplified). What are possible sources of water in the confined aquifer
portion of the well?
7. Compare you answer from Question 6 to your answer in Question 5 from ACTIVITY II.
WRAM-UP
EXTENSION: If you had to drill a well, which sites would you consider most favorable on the Well Log Ground
Water Chart (Cross Section)?