Aquifers and recharge areas
The student will do the following:
- Create a model of an aquifer.
- Describe how an aquifer works.
- Describe how pumping affects an aquifer
- Prepare a model presenting to local planners the important aspects of protecting recharge areas.
An aquifer is a layer of underground rock or sand
which stores and carries water. A recharge area is
the place where water is able to seep into the ground
and refill an aquifer because no confining layer is present.
Recharge areas are necessary for a healthy aquifer. Few rules
and regulations were made to protect these areas
Aquifers form significant natural reservoirs of water and can
form a large
proportion of water used for drinking purposes. In some countries
supply of water from underground can be the only source of
water available. The location and extent of aquifers is dependent
upon the geological conditions of the underlying rock. There
are three types of aquifers: perched, unconfined, and confined.
Perched aquifers occur in isolation as small
quantities of water in suitable confining strata
above the water table. Unconfined aquifers form
when the permeable strata forms an outcrop on
the surface. The upper part of the aquifer is
represented by the water table whose levels fluctuate
according to the groundwater balance. Confined
aquifers have impermeable strata above and below
and are not recharged by percolating rainwater.
Note that impermeable strata do not always represent
a complete barrier to water movement and that
recharge of the aquifer may take place many kilometers
away where the strata forming the confined aquifer
form a surface outcrop.
- aquifer: an underground layer of unconsolidated rock or soil that is saturated with usable amounts of water (a zone of saturation).
- recharge area: an area where water flows into the Earth to resupply a water body or an aquifer.
- Gather information from the city planning staff concerning a local recharge area that needs special protection from pollution and development.
- Have the students visit the site and take pictures of the area.
- After the trip have the students divide into groups of four.
1. Setting the Stage
- Tell the groups that they are going to conduct an experiment that includes creating an aquifer.
- Explain what an aquifer is and the importance of a recharge area.
- Brainstorm how this information will help us
develop a plan to protect our recharge area
A. Have each group mimic you as you:
- Place 4 inches of gravel in a bowl. Measure correct amounts of gravel, topsoil, and sand with the ruler.
- Put three syringes upright in the gravel. Do this before Step 3, or they will clog with sand. The syringes show an example of wells pumping from the aquifer.
- Hold the syringes and at the same time put 3 inches of sand on top of the gravel and 2 inches of topsoil over the sand.
- Add food coloring to 2 cups of water.
- Slowly pour enough water over the topsoil to saturate. This is the example of rain seeping into the aquifer and becoming groundwater.
- Put the bowl at eye level, observe, and record changes.
- Pull the stopper up to fill one syringe. This is an example of how water well pumping affects the aquifer.
- Repeat Step 6 using two syringes at once. Record changes in groundwater.
- Repeat Step 6 again using all the syringes. Record changes in groundwater.
3. Follow Up
A. Each group must answer the following questions:
- Is this aquifer model a recharge area?
- How do you know?
- Describe how an aquifer works.
- Are the sand and topsoil permeable or impermeable?
- What do you think would happen if more syringes
- Why is it necessary that we protect recharge areas?
A. Each group should brainstorm
ways to construct a model that they could present to
the city planning committee. This model will show why
this area needs protection. The model will show pictures
of the site, the results of the
experiments, and why a recharge area is important.
B. The winning group may present their model to the planning committee.
Johnson Cynthia C., Waterways, Division of Public
Information St. John's River Water Management
District, Jacksonville, FL, 1991.
Click here for Teacher Sheet #1
Click here for Teacher Sheet #2
Click here for Student Sheet
Printed with permission from
Michal L. Le Vasseur
Directions: Draw your investigation set up, record your observations,
and answer the questions.
1. Fill the syringe 1/3 full. Record changes in groundwater.
2. Fill the syringe 2/3 full. Record changes in groundwater.
3. Fill the syringe all the way. Record changes in groundwater.
4. Is this aquifer model a recharge area? Why or why not?
5. How does an aquifer work?
6. How are the syringes similar to wells in an aquifer?
7. Why is it necessary to protect recharge areas?
Aquifers and recharge areas (Adobe PDF document)