Our Water Resources
Susan Davidson
Indian Trail Junior High School
Olathe, Kansas

Overview:

These learning strategies seek to first define both aquifers and groundwater. Based upon these definitions, a model is then built which explains the formation of groundwater zones, water tables, and aquifers. A second activity focuses on the pollution of an aquifer.

Grade Level: 7th and 8th grade

Time Needed: 2-3 days

Geographic Themes:

Movement, Environmental Interaction

Kansas Social Studies Standard for Benchmarks, Grade Levels 8-K:

The student will understand the connections among people, places, and environments in the local school and community, Kansas, the United States, and different nations in the world.

National Geography Standard, Grades 5-8:

#7	The geographically informed person knows and understands the physical processes that shape the patterns of the Earth's surface.
#14	The geographically informed person knows and understands how human actions modify the human environment.

Outcomes:

1. To understand the sources of groundwater and will describe the water table as well as the zone structure of an aquifer.
2. To recognize the interrelationship between surface water and groundwater.
3. To describe how an aquifer may become polluted.

Performance Objectives:

1. The student will build a model of an aquifer using materials of various porosity and permeability.
2. Using the above model, the student will infer how groundwater zones and a water table form.
3. The student will observe which types of rock and soil hold the most water. Then the student will generalize the water-holding capacity of the minerals.
4. The student will make a model of two aquifers and measure the movement of contaminated groundwater in each.
5. The student will generalize from the model aquifers how groundwater can become polluted.

Vocabulary (see Glossary):

groundwater

zone of saturation

water table

zone of aeration

aquifer

Materials Needed:

A. Aquifer Model

1. stones
2. cut-up pieces of sponge
3. gravel
4. soil
5. vegetation (leaves, grass clippings)
6. water
7. clear glass or plastic container

B. Water Table Model

1. three clear glasses or beakers (identical in size)
2. gravel
3. sand (course)
4. soil
5. red food coloring
6. water
7. china marker

C. Polluted Aquifer Model

1. transparent plastic shoe storage box
2. modeling clay
3. course sand (nonsorted)
4. watering can, water
5. 12 plastic straws
6. metric ruler
7. dropper
8. green and red food color
9. paper towels
10. single-edge razor blade or scalpel
    

D. Resources

• DiSpezio, Linneruebe Lisowski, Skoog & Sparks. (1996). Science insights: Exploring earth and space. student text book. Menlo Park, CA: Addison-Wesley.
• DiSpezio, Linnerluebe Lisowski, Skoog, & Sparks. (1996). Science insights: Exploring earth and space. laboratory manual. Menlo Park, CA: Addison-Wesley.
• National Geographic Society. (1993). Water matters: Everyday. everywhere. every way. Washington, DC: Author.
• U.S. Geological Survey. (1995). Groundwater: The hidden resource. Denver, CO: Author. [Poster]

Procedures:
A. Aquifer Model

1. In a clear glass or beaker, arrange in approximately the same volumes: pebbles or stones, bits of cut-up sponge, gravel, soil, and vegetation.
2. Add water slowly until it collects to the top of the gravel.

B. Water Table Model

1. Fill three identical beakers: one with gravel, the second with sand, and the third with soil. These materials must be of equal volume and completely dry.
2. Add red food coloring to a supply of water. Pour an equal volume of water into each beaker.
3. Using a china marker, mark the outside of the beakers where the level of wet material is separated from the remainder of the material.
4. Observe and compare where the mark occurs in each of the three beakers.
5. Draw a diagram of the model on a sheet of paper. Label each diagram with the following: impermeable layer, zone of saturation, zone of aeration, and water table.
6. After a day, observe and compare the level where unsaturated and saturated soils separate.

C. Polluted Aquifer Model

1. Layer clay and sand as shown in diagram below. First, press a layer of modeling clay firmly against the sides and bottom of the plastic shoe box. Note that the clay should be sloped considerably higher at one end of the box than the other. This is the bottom of Aquifer A.
2. Place a layer of sand on top of the clay layer, following the slope of the clay. Sprinkle the sand layer slightly with water.
3. Put a thinner layer of clay on top of the sand again, paralleling the slope of the other layer. Press the clay layer against the sides of the box.
4. Add a layer of sand over the clay layer, again molding it to the slope of the layers below. This is Aquifer B.
5. Place a plastic straw into the model at a location 10 cm from the top of the slope and to one side. Insert the straw until it just touches the bottom layer of clay under Aquifer A.
6. Twist the straw slightly and remove it. You now have a core sample of the clay and sand in both Aquifers A and B.
7. Put a new straw into this hole. Using an eye dropper, place several drops of green food coloring into the straw. This represents the source of pollution for Aquifer A.
8. Repeat steps 5, 6, and 7 with another straw except place the straw down to the upper clay layer below Aquifer B and 10 cm from the side opposite the straw in step 5.
9. Place several drops of red food coloring into the hole. This is the source of pollution for Aquifer B. Refer to the diagram above for guidance concerning the placement of the straws.
10. Sprinkle entire surface of sand with water. This represents rain water. Allow the water to soak into the model.
11. Take core samples of the sand and day levels according to the illustration below. Insert 8 new straws all the way to the bottom of the box. Note that the straws should be evenly spaced about 5 cm apart.
12. Measure the distance in cm between each of these locations and the first two straws. Place the measurements on a chart, noting whether the distance is uphill or downhill from the original two straws. Twist each straw slightly to remove core samples.
13. Place core sample 1 on a purple towel. Use a single-edge razor blade and slit the straw lengthwise to examine the soil layers. On the data chart, note whether Aquifer A and Aquifer B have taken on color. Also note what color each aquifer is, as well as the intensity of that color.
14. Repeat step 13 for the seven remaining holes.
15. A sample data chart is provided below, but expect the actual data to vary.

Core Sample Distance from the Source of Pollution (cm) Color Observed . Green Source Red Source Aquifer A Aquifer B 1 11 uphill 5 uphill none none 2 10 downhill 5 downhill dark green dark red 3 14 downhill 10 downhill green red 4 17 downhill 15 downhill light green light red 5 5 uphill 11 uphill none none 6 5 downhill 10 downhill dark green dark red 7 10 downhill 14 downhill green red 8 15 downhill 17 downhill light green light red

Assessment Activity:

1.

Water Table Model Describe what happened when you first poured water into each beaker. What force moved the water down? Is the location of the water table the same in each beaker? Compare and contrast the changes you observed in the location of unsaturated and saturated soil from the first day to the second day. What caused this change? Suggest one way to prevent this. What factor seems to determine which water level is the lowest? Rank the water-holding capacity of soil, sand and clay. Use a scale of 1-3, with 1 having the lowest water-holding capacity, 3 having the highest water-holding capacity.

2.

Polluted Aquifer Model Did you observe red pollution in Aquifer A? Why or why not? Did you observe green pollution in Aquifer B? Why or why not? Describe any patterns of pollution you observed in Aquifers A and B. Compare and contrast the pollution patterns in each. What does the modeling clay represent in nature? Why was sand used in your model? Briefly explain and conclude how pollution enters groundwater.

Assessment:

1. Record level of completion of model aquifer.
2. Check for accuracy of assessment #1.
3. Check the data chart for completion.
4. Check accuracy of assessment #3.

Extensions:

1. The Ogallala Aquifer allowed agriculture to flourish in areas of low rainfall. Students could locate and map this important aquifer in Kansas. Then a comparison of crop fields before and after irrigation would show the economic importance of this resource.
2. Encourage students to research various sources of groundwater pollution and various strategies to protect this resource from future damage.

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irc staff 11/28/97 (updated kn 06/17/99) Disclaimer