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Aquifers and Groundwater  

Confined and unconfined aquiferGrade Level: 4-6

Subject: Science

Time Frame:  One 45 minute class period.

Overview: Using peer cooperation and communication students will build and experiment with a model aquifer system.  Through this model, students will acquire relevant vocabulary to enhance their understanding of the environment and explore the importance of groundwater, aquifers, and their important components.

Students will further investigate how the Barnegat Bay was formed and how human water usage is directly related to the amount and location of brackish water in the Barnegat Bay.  

Image Source: http://www.learner.org/courses/envsci/unit/text.php?unit=8&secNum=3#confined_unconfined_aquifer      

NJ Core Content Standards

STANDARD 5.1 (Scientific Processes) All students will develop problem-solving, decision-making and inquiry skills, reflected by formulating usable questions and hypotheses, planning experiments, conducting systematic observations, interpreting and analyzing data, drawing conclusions, and communicating results.

A. Habits of Mind

·          Evaluate the strengths and weaknesses of data, claims, and arguments.

·          Communicate experimental findings to others.

·          Recognize that curiosity, skepticism, open-mindedness, and honesty are attributes of scientists.

B. Inquiry and Problem Solving

·          Identify questions and make predictions that can be addressed by conducting investigations.

·          Collect, organize, and interpret the data that result from experiments.

STANDARD 5.8 (Earth Science) All students will gain an understanding of the structure, dynamics, and geophysical systems of the earth

B. Atmosphere and Weather

·          Describe the composition, circulation, and distribution of the world's oceans, estuaries, and marine environments.

·          Describe and illustrate the water cycle.

D. How We Study the Earth

1.        Utilize various tools such as map projections and topographical maps to interpret features of Earth's surface.

STANDARD 6.6 (Geography) All students will apply knowledge of spatial relationships and other geographic skills to understand human behavior in relation to the physical and cultural environment.

A. The World in Spatial Terms

·          Translate maps into appropriate spatial graphics to display geographical information.

·          Use geographic tools and technologies to pose and answer questions about spatial distributions and patterns on Earth.

B. Places and Regions

·          Explain how regional systems are interconnected (e.g., watersheds, trade, transportation systems).

Multiple Intelligences

Spatial, Kinesthetic, Linguistic, Interpersonal, Intrapersonal, Logical/Mathematical, Naturalistic

 

Materials

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Access to internet or download of groundwater video at http://www.youtube.com/watch?v=uQRvN6MUajE

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Large tupperware container, fishtank or other water tight container

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Sand

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Modeling clay

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Gravel

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Green fabric

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Water in squirt bottle

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Turkey baster

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Food coloring

Objectives

SWBAT

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·        Explore the relationship between the aquifer system and the groundwater

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·        Connect the aquifer system to the water cycle previously learned

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·        Investigate how the aquifer system works

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·        Experiment the aquifer system and ground water concepts to their lives

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·        Relate how the aquifer system and ground water concepts to their lives

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·        Demonstrate how it all is related to the Barnegat bay

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·        Recall how this model and the lesson is directly related to the Barnegat Bay

 

Anticipatory Set:

Teacher will toss some beach balls around to the students, while he / she asks students if they ever dug a hole deep enough in beach sand away from the water for water to seep into the hole from the bottom.  Teacher will explain that this is very similar to how water enters a well dug into an aquifer collects groundwater and that this is what they will be learning about today.

Sequence Instruction:

1)      In this activity students will focus on understanding how the infiltration of precipitation forms groundwater.  To introduce this, if possible play the movie on groundwater at http://www.youtube.com/watch?v=uQRvN6MUajE and discuss this with your students.

***If the following activity seems to take too long for a given time period, teacher is able to create this model prior to class and present students with the information as they observe the model. Students will still be able to learn about the aquifer, new vocabulary, and experience the groundwater connection with Barnegat Bay and our own water use. Teacher would then able to move to the next lesson plan to connect water use with the groundwater model.***  

2)      Teacher will separate students into groups of about 10.

3)      The groups will be given the necessary materials to be used. 

4)      Students will be informed that today they will be creating their own aquifer system. 

Note to teacher: The model will demonstrate how the freshwater from the rain infiltrating the ground replenishing the groundwater and flow into the Barnegat Bay (the “lake” on the one side of the container) with freshwater to create brackish water as it combines with the ocean water. This is also the same groundwater formed to be taken up by the water tower for human use.

5)      Each group will have the students circle the materials and each student will do one of the steps around the circle as described:

a.       Student 1:  Pour ¼ inch of white sand on the bottom of the container

Teacher will explain: That sand represents an aquifer.  Aquifers can be made of many different types of materials from the earth.  Around New Jersey, by the east coast our aquifers are made mostly of sand and gravel. Because the material within such sediments has lots of spaces, they can hold lots of water.  Normally the water would keep on running through such sediments because there’s nothing to hold them in the spaces, but often the sand sits on a later of bedrock which won’t let the water sink in any further (like the bottom of the container holds the water, preventing it from running out onto the desk and all over the floor!).  The water can move horizontally within the sand, so if the sand layer is on a slope the water will run downhill through the spaces, but it can’t sink any further vertically because of the rock layer below.   When all the spaces between the grains of sediment are filled with water, we say that the layer is “saturated” with water.  The top of the saturated layer is termed the “water table”.  On wet years the water table will be quite close to the surface, whereas in drought years you would have to go much deeper to find saturated sediments and the water table will thus be much deeper (lower).

b.      Student 2: Pour water into the sand only to wet it, *IT IS IMPORTANT* for this exercise that student not fill the water up past the sand.

Teacher will explain: The water being poured demonstrates how the sand particles can hold the groundwater forming the aquifer.

c.       Student 3: Flatten the clay into a pancake large enough to cover about 2/3 of the sand layer.  Press the clay against three sides of the container to keep about 2/3 of the sand sealed between the container below and the clay above.

Teacher will explain: The clay is the “confining layer” that often sits on top of an aquifer and prevents new groundwater from entering the aquifer in this area. Areas where there is no “top” on the aquifer are called “recharge” areas because water here can get into the aquifer.   The bits of the aquifer with rocks above and below them are termed “confined” aquifers

d.      Student 4: Push a syringe or turkey baster through the clay and into the sand on the “confined” side of the container.

Teacher will explain: This represents the “bore hole” or deep well from which many  towns pump water out of aquifers to provide the inhabitants with their water for their homes and businesses. 

e.       Student 5: Place a second layer of sand on top of the clay.

Teacher will explain: The second layer of sand represents the unconfined portion of a second aquifer which is again collecting groundwater. In many areas of New Jersey there are 2 or 3 different aquifers and different depths, each representing a layer of “porous” rock or sediment (like sand) separated by layers of solid rock  (http://water.usgs.gov/ogw/aquiferbasics/uncon.html).   A hole dug into this unconfined aquifer is called a well, and that well will fill with water, just so long as there is water in between the grains of the aquifer sediment in the areas near the well.

f.        Student 6: Place fine grained aquarium rocks so that they cover both the sand and clay. 

Teacher will explain: The top layer is the layer one we usually see and call “soil”.  Because this soil is porous, groundwater flows through it (infiltrates it) and flows into to lower layers of earth. The top layers of soil usually contain some water, but also have many empty spaces between soil grains.  Such soil is termed “unsaturated”.  Only if all the areas of soil below it are so full of water that the newly arriving rain has no place to go would this soil become “saturated” and this would usually not last for long after the rain stopped and the water starts to drain away.  See diagram below (or show class) for a better understanding.

g.       Student 7: Tip the model with the end with the "constrained aquifer" (with the baster in it) toward the bottom of the slope (take care to do this without knocking the baster over).

Teacher will explain: This represents the typical slopes of land between the mountains in New Jersey’s Western areas and the ocean and Barnegat Bay toward the East. 

h.       Student 8: Place a  thin piece of green porous fabric over top of the model.

Teacher will explain: This represents the plants growing on the soil surface.

i.         Student 9: Slowly pour water on the top of the hill while the rest of the students watch where the water runs, down the hill, into the rocks, sand and clay as well as forms a “lake” on side of the container.

Teacher will ask: Which directions did the water flow?  Did it flow on the surface (over the green) or through the soil?  Or both? Where does the water end up (should get some in each of the aquifers, as well as some creating a pool at the downslope end). 

It is important to point out that the “lake” formed by the stream and groundwater represents the Barnegat Bay.  This is a good way to show how not only surface run-off water, but a lot of the groundwater in unconstrained aquifers contributes to replenishing the Barnegat Bay’s freshwater.

Something to research later:  Does the town you live in get its water from surface water (a river or stream) a unconfined aquifer or a confined aquifer? (It depends on the area whether the water company collects their water from confined or unconfined aquifers.

j.        Student 10:  Squeeze the bulb gently while supporting the tube (so it doesn’t pull out) and allow the it to relax.  Hopefully water will comes up the tube. 

 Teacher will explain:  This models what happens when your local water utility uses the bore hole and pump to obtain the water you use in your home and yard (the water is often stored in water towers within the township). 

Question:  Where does the water come from to replace the water removed (answer: the unconstrained parts of the aquifer where rain can penetrate into the sand).  

Observation:  If you pull water out too fast with your baster you will find that no more water comes out, even if there is water is still elsewhere in the sand in model.  This is because the water can’t flow through the sand fast enough to get to the baster in time to get sucked up.  The same happens in aquifers.  Recharge areas are often hundreds of miles from the location of the town’s “bore holes”.  If you pull water out too fast new water can’t reach the area being pumped as fast as the water is being removed, and the aquifer “runs dry”.

 (http://www.freedrinkingwater.com/water_quality/experiment4-build-aquifer.htm)

It is important for the teacher to prompt students to think of the entire project, and to relate it to what's going on in the area where they live.  Helping students to see the connection between the content and their lives will help them to see why this is important to understand.  In addition, they will use much of this information again in the lecture on water conservation, so linking water use with the processes in this lesson plan is another important learning goal.  The goal is to get the entire class to realize that the fresh water running into the Barnegat Bay as surface and ground water is the same water we are sucking up from the aquifer (formed by the ground water) to provide the water we use in our homes and communities.

When you flush your toilet or let the water down the drain of your sink, bath or shower it is sent to a sewage processing plant and then, in Ocean County, is pumped into pipes that go out into the ocean.  Thus the water pulled out of the aquifers and wells by local water utilities doesn’t go back into the ecosystem and thus isn’t there to fill the Bay.

Assessment Activity:

Have each student write a paragraph explaining what you observed from this model.

Alternately have the students draw a side-view picture of the model aquifer and label the following: bedrock,  confined aquifer, unconfined aquifer, water table, soil (land), bore hole (deep well) and Barnegat Bay.

Closure:

Students fill out an exit slip explaining why it is important for them to learn about groundwater in order to understand why we need to conserve water for the health of the Barnegat Bay.

Resources and References

Great Website with list of links  http://mail.groundwater.org/kc/kc.html 

The following posters are optional for the activity, but will greatly enhance it and single copies can be ordered free:

Groundwater the Hidden Resource and How Do We Treat Our Wastewater?

U.S. Geological Survey-Branch of Distribution
P.O. Box 252860
Denver Federal Center
Denver, CO 80225

Diagram of how ground water occurs underground.

(http://ga.water.usgs.gov/edu/earthgwaquifer.html; http://ga.water.usgs.gov/edu/earthgwwells.html)

What is groundwater and picture   http://www.groundwater.org/kc/whatis.html

 

Power point on how to make the aquifer  http://www.epa.gov/safewater/kids/flash/flash_aquifer.html

Why is ground water important? http://www.ngwa.org/programs/educator/lessonplans/groundwater1.aspx

 

Other important definitions

1.      The amount of pore space present in rock and soil is known as porosity.

2.      The ability of fluids to travel through the rock or soil is known as permeability.

3.      The permeability and porosity measurements in rock and/or soil can determine the amount of water that can flow through that particular medium. A “high” permeability and porosity value means that the water can travel very quickly.

4.      Ground water can be found in aquifers. An aquifer is a body of water-saturated sediment or rock in which water can move readily.

5.      There are two main types of aquifers: unconfined and confined.

6.      An unconfined aquifer is an aquifer that is exposed to the surface of the land. Because this aquifer is in contact with land, it is impacted by meteoric water and any kind of surface contamination. There is not an impermeable layer to protect this aquifer.  It is also where new water can enter or “recharge” the confined areas of the aquifer

7.      A confined aquifer is an aquifer that has a confining layer that separates it from the land surface. This aquifer is filled with pressurized water (due to the confining layer).

8.      Porosity and permeability of the sediment, soil, and bedrock in the area also affects the recharge rate of the ground water. This means that in some areas, the ground water can be pumped out faster than it can replenish itself. This creates a number of problems. (http://www.ngwa.org/programs/educator/lessonplans/groundwater1.aspx )

Lesson Plan Extensions:

Edible Aquifers – ice cream sodas / parfaits: http://mail.groundwater.org/kc/activity5.html and http://www.dnr.state.wi.us/org/caer/ce/eek/cool/ameliaedibleaquifer.htm

Class activity on different water usages using strings and jugs: http://www.nps.gov/archive/wica/Hydrology/PDF/Hydrology-Water_Works.pdf

More experiments about soil layers retaining groundwater: http://www.nps.gov/archive/wica/Hydrology/PDF/Hydrology-Soil_Layers_and_Groundwater.pdf 

 

Useful Resources on Aquifers in New Jersey

USGS Aquifer Information http://nj.usgs.gov/gw/table_1.html

Point Pleasant Borough's page on watersheds and aquifers: http://www.ptboro.com/gov_pages/open%20space/index.html

Status of the water supply in South Eastern New Jersey: http://www.gehwa.org/Water%20Resource%20Files/South%20Eastern%20Water%20Supply%20Executive%20Summary.pdf

Understanding the Barnegat Bay Watershed:  http://www.bbep.org/Chapters/chapter_2.pdf

EPA's Drinking Water and Ground water page: http://www.epa.gov/safewater/kids/kids_4-8.html

 

Other Resources

How does water get from the source to your home?  http://www.njawwa.org/kidsweb/treatment/treatment_distrib_to_home.htm

 

TEACHER FEEDBACK REQUEST:  We are always to working to improve these lesson plans. If you use this lesson plan, we'd love to hear from you with your thoughts, comments and suggestions for future improvements.  Please take the time to fill in our survey at http://www.zoomerang.com/Survey/?p=WEB229JAHPF748.  Thanks!

 

 © 2009.  Amanda Traina (Author), Louise Wootton (Editor)

 

    

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