Hands-on Activity: How Fast Does Water Travel through Soils?
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Familiarity with basic number operations, including addition, subtraction, multiplication and division.
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
To share with the entire class:
Introduction/Motivation (Return to Contents)
When it rains, where does all the water go? The water is in constant motion—some of it travels along the surface to rivers or lakes, some of it is absorbed by roots and plants, some evaporates and returns to the atmosphere, and much of it goes underground! Let's imagine pouring water onto a mountain of sand we have built on the beach. Where would that water go? Some portion of the water would go down the sides, while the rest is absorbed by the sand. Water tries to fill voids between sand or soil particles. Permeability is a measure of how willing the sand or soil particles are to let water fill the spaces between them.
Permeability is very important in civil engineering. In fact, permeability is often studied by engineers when designing water resource structures, such as dams. When designing and building retaining walls, excavations, bridges, land slopes, etc., engineers perform soil permeability analysis. Water flow analysis is also important in these construction projects.
For instance, in landslides and earth dams, the concepts of water flow and permeability are often used to estimate or predict the amount of water expected to come out in a certain period of time. The stability of slopes (such as in highways, excavations and dams) mainly depend on the presence of water runoff, infiltration and permeability because the water pressure built inside earth bodies causes additional forces that eventually act against the overall stability of the project.
Having knowledge of permeability allows engineers to design, calculate and build great structures, as well as correct and mitigate natural disasters in order to guarantee safe conditions and reduce the risk of damage or collapse.
(Optional: Show students the attached Soil Permeability Presentation.)
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Permeability values can be determined in the field or in the lab. Soil permeability is determined in the lab with the help of two tests: constant and falling head (see attached PowerPoint presentation for details). In the field, soil permeability is determined by a pumping test, in whcih water is pumped from a well at a constant flow rate and the time it takes for the water to flow to reach steady state is measured (having a constant groundwater level makes the water come back to its original position).
This hand-on activity has three parts. First, students are introduced to permeability tests. Then, they conduct permeability tests with the use of a chronometer and rulers (students measure volumes and take analogue times). Finally, students conduct permeability tests with ultrasonic sensors, allowing them to minimize measurement error by using better technology (mechatronic components).
If possible, have students perform each test for all three soil samples. After testing soils with varying permeability (such as clay, sand and gravel), have students analyze their data and see that collecting data with digital vs. analogue practices affects the quality of the data collected.
Before the Activity
With the Students
Part 1: Basic Permeability Test with Soda Bottles
Without any sophisticated permeameter device, have students run their first soil permeability test.
Part 2: Permeability Test without Ultrasonic Sensor
To run the test without digital measurements:
Part 3: Permeability Test With Ultrasonic Sensor
This section is devoted to running the same experiment with another data recording system, a LEGO ultrasonic sensor. Ultrasonic sensors are able to detect the proximity of objects (in this case a changing water level). Conducting the experiment a second time with the use of an ultrasonic sensor allows students to witness the differences between data-gathering with analog (manual) and digital (mechatronic) tools.
Attachments (Return to Contents)
Assessment (Return to Contents)
Worksheet: Have students complete the Soil Permeability Pre-Evaluation. Review their answers to gauge their familiarity with the activity topics.
Activity Embedded Assessment
Student Explanations: Randomly select students to explain what they see during the permeability tests. Ask them to tell you which soils are more or less permeable based on the variety of samples you have in the classroom. Have them defend their answers with data and observations.
Post Activity Worksheet: Have students complete the Soil Permeability Post-Evaluation. Review their answers to gauge their takeaways from the activity.
Question and Answer: Ask students the following questions. Have the students write down their answers. Call on students to share their answers with the class. Did everyone get the same answer?
References (Return to Contents)
ContributorsEduardo Suescun, Ryan Cain, Russ Holstein, Magued Iskander
Copyright© 2012 by Polytechnic Institute of New York University
Supporting Program (Return to Contents)Applying Mechatronics to Promote Science (AMPS) Program GK-12, Polytechnic Institute of New York University
Acknowledgements (Return to Contents)
This activity was developed by the Applying Mechatronics to Promote Science (AMPS) Program funded by National Science Foundation GK-12 grant no. 0741714. However, these contents do not necessarily represent the policies of the NSF and you should not assume endorsement by the federal government.