Hands-on Activity Where Does All the Water Go?

Learning Objectives

After this activity, students should be able to:

• Understand how water flows through the ground.
• Compare a groundwater model with what it represents.
• Find the velocity of groundwater flow through a model.
• Describe the role of engineers in the treatment of aquifers.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

Common Core State Standards - Math

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

Each group will need:

• A groundwater model tank, such as one made by enVISION Environmental Education; or use the movie in the attached PowerPoint® presentation.
• 1 sheet of large poster board
• Variety of colored markers (including brown and blue)
• Three copies of the Where Does the Water Go? Worksheet

Worksheets and Attachments

Pre-Req Knowledge

Basic number operation skills

Introduction/Motivation

The sun causes water to evaporate into the atmosphere, and then once water vapor condenses to form clouds, water can return the surface of the Earth in the form of rain. What happens when it rains? Where does the water go? (Accept student answers.) It either runs over the surface of the earth to a body of surface water — such as a lake, river or stream — or it filtrates down through the ground. Gravitational force is the driving force behind water's movement into the ground. Once in the ground, it becomes groundwater. Groundwater flows very slowly through the dirt or soil under the ground to a space called an aquifer.

(Draw the following figure on the white/chalk board.)

What is soil? Can you think of different types of soil? How would these types of soil affect the water's ability to flow through the soil? (Answer: Soil with larger pore spaces allows greater water flow. For example, water flows through rocks or large pebbles faster than through sand.) We call the spaces between the individual particles of soil, pores or porosity and the ability for the water to flow through the soil as permeability.

Environmental engineers have developed methods to treat the water in aquifers so that it can be used as a source for drinking water. However, sometimes toxic chemicals that are dumped into the ground seep into our aquifers and make the water harmful to use. Environmental engineers not only figure out how to treat the water for these hazardous chemicals, but they also use groundwater modeling to determine where the chemicals came from and how fast they are moving through the soil. When they model the groundwater flow, they need to figure out the porosity and permeability of the soil, the direction of flow and the velocity of the chemicals. They need to look at these measurements in the areas surrounding a chemical spill, because chemicals spread out in all directions. This is called a chemical plume. Today, we are going to look at a groundwater model and investigate different types of soil. We will also calculate the velocity of a harmful chemical to see how fast it flows through the different soils.

Procedure

Before the Activity

• Obtain a groundwater tank of some sort. If this is not possible, the activity can be replaced with the "What's Down the Well" activity (from Lesson 4 of this unit). Find a groundwater model to use; many schools have one. If yours does not, you could likely borrow one from a local college/university. (Also, it would be a good idea to check with surrounding high schools.)
• Make enough copies of the Where Does the Water Go? Worksheet so that each student has their own copy.

With the Students

1. Write the following terms on the board and ask students to think about what they mean: water table, groundwater, aquifer and soil.
2. Demonstrate groundwater flow using a groundwater model tank. It is best to have different types of soil — one coarser grained like gravel and a finer grain soil (like sand) — and include an example surface water feature (like a lake). Add food coloring to the surface water so students can visualize how the water can flow from the surface water to the ground and then move under the ground. Remind students that gravity is the force that causes water to flow and move in this way.
3. Ask students how fast they think the water is flowing through the tank. Ask the students to recall anything they know about velocity. Tell them velocity is equal to distance divided by time. Ask students how they could calculate the groundwater velocity.
4. As a class, have one student measure the length of the tank and one student time how long it takes for die added to one side of the tank to reach the other side of the tank. With these two numbers they should be able to calculate velocity.
5. If time permits, have students calculate the velocity through individual types of soils.
6. In groups of three, have students make a poster of what they saw in the demo. Their posters should include all the different types of soil in the tank and a key that labels and describes the different types of soils. Students should also label and define the following items: water table, aquifer, flow direction.
7. If time allows, have students present their drawings to the classes.
8. Have students complete the Where Does the Water Go? Worksheet in class or as homework.

Vocabulary/Definitions

Aquifer: Layer of soil or rock containing water that yields useable water when pumped.

Groundwater: Water under the ground often in permeable layers of rock or soil.

Saturated zone: The zone underground that is completely saturated with water.

Vadose zone: Also know as the unsaturated zone, it is the zone underground above the water table that is not saturated with water.

Water table: The line between the saturated zone and the vadose zone.

Assessment

Pre-Activity Assessment

Discussion Question: Solicit, integrate and summarize student responses.

• An environmental engineering firm has been notified of a chemical spill outside the city. What do you think they need to know about the area of the spill before they can begin treating it? Accept all answers.

Brainstorm: In small groups, have students engage in open discussion. Remind students that in brainstorming, no idea or suggestion is "silly." All ideas should be respectfully heard. Encourage wild ideas and discourage criticism of ideas. Write down all of their ideas on the board. Do not provide the answer. Group their answers together as much as you can. For example, ideas having to do with: water, people or animals. Ask students:

• What is an aquifer?
• What is groundwater?
• What does water looks like under they ground?

Activity Embedded Assessment

Posters and/or Presentations: Have students make a poster of the groundwater demo labeling and defining the new vocabulary. (If time allows have students present their poster to the class.)

Post-Activity Assessment

Question and Answer: Ask students the following questions. Have the students write their answers down on a piece of paper first, but stress the answer will not be graded. After everyone has had a chance to write an answer down, call on a student to answer the question. Did everyone get the same answer?

• What is an aquifer? (Answer: Soil or permeable rock that is saturated with water.)
• What is the water table? (Answer: the line that water comes to in soil)
• Does groundwater flow like a river? (Answer: No, normally water flows slowly through the pores in between soil grains.)
• What force causes water to move through the ground? (Answer: Gravitational force.)
• What does saturated mean? (Answer: When all the pores are filled with water.)
• What do engineers have to know about groundwater flow when treating the aquifer for harmful chemicals? (Answer: porosity, permeability, direction and velocity of flow.)
• Why must engineers take measurements in all areas surrounding a chemical plume? (Answer: Because chemicals often spread in all directions, not just in a straight line.)

Problem Solving: Present the class with the following problems and ask the students to calculate which case has the greatest velocity. (Answer: Case B) Which soil had the largest permeability? (Answer: Case B)

• Case A: A chemical reaches the local city drinking water supply 25 miles away in 36 hours. (Answer: 25 miles / 36 hrs = 0.69 miles/hr or 0.01 miles/minute)
• Case B: A chemical enters the aquifer 5 miles below the spill in 120 minutes. (Answer: 5 miles / 120 minutes = 0.04 miles/minute.)
• Case C: A chemical is spilled on March 1st. It enters the local aquifer 30 miles away on March 15th. (Answer: 30 miles / 15 days = 2 miles/day = 0.08 miles/hour or 0.001 miles/minute.)

Troubleshooting Tips

There are many different ways to create a tank to simulate groundwater flow. It can be done using a fish tank and creating siphons with ½" plastic tubes on either end. Search the internet for ideas. A few states, such as Wisconsin, have a website listing places from which you can borrow a tank. In addition, if there is a university in your area, it is likely that a tank exists that can be used to model groundwater; begin with the environmental engineering department.

Activity Extensions

Have students build their own groundwater module.

Activity Scaling

For 6th grade, use less technical vocabulary for younger grades.

For 7th and 8th grades, do activity as is.

References

Copyright

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.