Chapter 5A: Groundwater – I dig it!

---

To the teacher

Purpose

To help students see the extent and importance of groundwater in Canada.

Subject areas

History, Environmental Studies, Math, Language Arts, Science

Procedure

Review: Remind the students that groundwater is a large part of the hydrologic cycle and the world's water supply. Because we can't see groundwater, we tend to forget about it.

• Groundwater is an essential and vital resource for about a quarter of all Canadians, yet few of us understand or appreciate its value. Our knowledge about groundwater seems to depend on where we live in Canada.
  
  
• Ask the students if they have ever drunk water from a well. Try to find out how much they know about groundwater before distributing the information sheets.

Vocabulary aquifer confined crevice impermeable unconfined unsaturated

References

• Freshwater Series A-5: Groundwater – Nature's Hidden Treasure
• A Primer on Fresh Water: "Water – Underground"

Student information

Picture the postcard view of Canada. What do you see? Sparkling blue lakes, long meandering rivers, and glistening white glaciers. Groundwater, which exists everywhere under the surface of the land, is not part of this picture. And because it is "hidden" from view, we tend not to think of it too much, instead we concentrate on the quality of our beautiful lakes and rivers. The question is, should we be concerned about groundwater quality since there is so much of it and since it is protected by ground cover? What do you think?

What's going on down there?

About one third of all the fresh water in the world is found underground! Look at the diagram "Groundwater and the world's freshwater supply" to get an idea of the amounts.

Groundwater and the world's freshwater supply

Over one quarter (30.3%) of Canadians rely on groundwater for all their daily needs. If you look at the diagram of Canada below you can see which areas depend entirely on groundwater and which regions hardly use it.

Percentage of population reliant on groundwater

Water witches??

Your Current Events class this afternoon has set off a special spark of interest in you. As you thumb through the newspaper looking for headlines of noteworthy events in the world, your eyes light on the following:

Water Witch Will Find Water For You Using the latest "divining rod," this water witch will point out the best place to dig a well on your property!

Come on now, water witch? Divining rod? Pointing to water in the ground? Sounds like one of these headlines you read at the grocery checkout.

Believe it or not, many people will not start to dig a well until they have called in a water witch, or diviner, to locate the spot where they are likely to find water. A water witch will use a steel divining rod or a forked stick (or even a clothes hanger!) and walk back and forth over the property. When the rod twitches or vibrates over a certain spot, this means there is groundwater below. Fact or fiction? Check it out with older people in your area. You may be surprised by some of the stories you hear.

Whether water witches can locate the best spot to dig for groundwater or not, the fact is that there is lots of groundwater beneath us. Even under deserts!

Did you know? Groundwater provides nearly all the water used to raise livestock in Canada.

Groundwater flow

We know that groundwater moves underneath the soil because it is part of the hydrologic cycle, but just how fast does it flow?

Groundwater flows through the soil at different rates: it may move quickly, depending on the kind of soil it is in, but fast flow is unlikely; it can move as slowly as 10 centimetres a day and travel only 1 to 2 kilometres a year; or, one water molecule can be in the ground thousands of years before being discharged.

When you think of groundwater flowing you should know that it does not flow as our rivers above ground do, nor does it collect in underground lakes.

Rather, it is found almost everywhere underground – in the spaces between particles of rock and soil, or in crevices and cracks in rock – as you can see in the following diagram.

Look at the diagram "Groundwater flow". In it you can see the unsaturated zone, where the spaces in the rock and soil contain air as well as water; and the saturated zone, where the water is called groundwater and it is always on the move.

Remember: Although groundwater may move very slowly through the system, it is a very important part of the hydrologic cycle. Eventually it finds its way back to the lakes, rivers, and oceans.

Aquifers

The underground areas of soil or rock where quantities of water are found are called aquifers. These aquifers are the sources of wells and springs.

Look at the diagram "Aquifers and wells" and see if you can tell the difference between confined and unconfined aquifers.

Did you know? Water can be hard or soft. Groundwater tends to be harder than surface water because it has been filtered through soil and rock, picking up some minerals from the process. Which do you think would make it easier to work up a good lather in the shower or bath – hard or soft water?

What is a water table?

That's what we call the top or surface of the groundwater supply. Water progresses slowly down through the sand and gravel until it comes to impermeable rock where it can't go any further down because the rock is watertight. Above this rock is the groundwater supply or the saturated zone, and the top part of that supply is the water table.

Learning activities

Activity 1 – Math, Research

Check back to the diagram "Percentage of population reliant on groundwater".

• Show these percentages on a bar graph.
  
  
• Research: Find out how many people live in Canada. How many people live in each province and territory? Based on the percentages of groundwater users provided, calculate how many people from each province rely on groundwater supplies.
  
  
• If there is an average of four persons per household, how many households rely on groundwater?
  
  
• Make up five math problems based on your research.

Research: Why do so few people in the Northwest Territories use groundwater? Why is this so different from the Yukon? Why does everyone in Prince Edward Island use groundwater?

Explain the use of groundwater in your own province or territory. Do you have lots of other sources of supply?

Activity 2 – Local Research

Which witch is the water witch?

As mentioned earlier, it might be interesting to find out if people in your area have ever used "witches," or "diviners," to locate good places to dig wells especially if you live in a rural area, or if your parents and grandparents have come from a rural area.

You may find out other beliefs or superstitions which have some truth in them.

Interview people from the community. Ask them about water witches, or diviners, and find out if they have heard about them. Come back and report to the class what you have learned.

If you can find someone to give you instructions, try your own hand at being a water witch.

Activity 3 – Science

Groundwater occurs in the tiny spaces between soil particles (silt, sand, and gravel) or in cracks in bedrock, much like a sponge holds water. The underground areas of soil or rock where abundant quantities of water are found are called "aquifers," and this is where we find the sources of wells and springs which provide water for 26% of Canadians.

1. Demonstrate how much water can be held between grains of sand:
   
   
   • Fill a container with sand and gradually pour in water. You will be surprised at the amount of water a "full" container can hold.
     
     
2. Test to find out which soil is the most absorbent: sand, gravel, potting soil, or clay. This will also show you which soil is easier for water to travel through quickly. (Just for review, absorbent means that something will hold water.)
   
   What you will need:
   
   
   • four beakers the same size (or you can use funnels with cloth covering the hole)
   • one beaker to hold 500 milliliters of water
   • four kinds of soil: sand, gravel, clay, potting soil
   • water
     
     
   What to do:
   
   
   • Fill each of your beakers three quarters full with sand.
     
     
   • Put 500 milliliters of water in the water-beaker.
     
     
   • Pour water into the sand until the soil is saturated. Record the exact amount of water the sand absorbed.
     
     
   • Top up the water beaker to 500 milliliters three more times and repeat the same step with the clay, the gravel, and the potting soil.
     
     
   • Show the results on a bar graph.
     
     
   Which type of soil is the most absorbent?
   
   
   • Do you think the results will be the same each time you do the experiment?
     
     
   • Report your findings. Write a sentence for each of the different kinds of soil. Find out what kinds of soil can be found in the area where you live.

Activity 4 – General

Look at the diagram "Aquifers and wells." Explain the difference between confined and unconfined aquifers. What is an artesian well?

Activity 5 – Historical Review

You have just met a very befuddled water molecule who has recently been discharged from an underground source. The water molecule is having trouble understanding all the changes that have occurred in Canada during the past 300 years.

• Your assignment is to review what the water molecule has missed. Explain the changes and events clearly so that they can be easily understood.
  
  
• Brainstorm together. What areas need to be covered in your review? For example:
  
  
  • Who lives in Canada? Where did people come from?
    
    
  • What historical events have happened in 300 years. Make a time line.
    
    
  • What has happened in science? Technology?
    
    
  • What are recreational uses of water?
    
    
  • What about living accommodations? Cities? Transportation? Boats? Water ways? Roads? Water contraptions like taps, showers, pipes, toilets, dishwashers?
    
    
  • Explain new sources of water pollution and the need for water treatment plants.
    
    
  • Identify other areas that need to be explained.

Activity 6 – Environmental Studies

Contact your local Department of Health to find out the regulations controlling the drilling of water wells in your area. Write a report, create a chart, or make a presentation to the class.

Activity 7 – Research

Do you know what a "sink hole" is? If you lived in parts of the United States like Texas or Florida, you might be familiar with one. Sink holes occur where there is not enough water on the surface to support the people who live there, so they keep pumping up the underground supply. Unfortunately, the underground supply only contains so much water; the groundwater supply is depleted (or mined) and the ground sinks.

Find out more about sink holes. Have there been any around where you live? Explain. What can be done to prevent sink holes?

---

| What's New | About Us | Topics | Publications | Weather | Home |

The Green LaneTM, Environment Canada's World Wide Web site

Important Notices