Groundwater

Groundwater

Middle School

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Learning Objectives

• Define groundwater and how it gets underground through the process of infiltration.

• Explain the difference between porous, permeable, and impermeable rock layers.

• Describe an aquifer, the water table, and factors affecting its level.

• Understand the key concepts of capillary action and what fossil water is.

Key Vocabulary

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Groundwater

Freshwater that is located and flows beneath the Earth's surface in soil and rock spaces.

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Aquifer

An underground layer of rock or sediment that holds and stores a usable amount of groundwater.

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Water Table

The highest level of the underground surface where the ground is completely saturated with water.

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Permeable

A quality of materials that allows liquids like water to pass through them via pores.

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Infiltrates

The water seeps into the soil from the surface, moving into the spaces between soil particles and aggregates

What is Groundwater?

• Groundwater is fresh water found beneath the Earth's surface.

• Surface water seeps into the ground through a process called infiltration.

• This water fills the empty spaces in soil and rock layers.

Multiple Choice

What is the process called when water seeps down from the surface into the ground?

• Saturation

• Infiltration

• Evaporation

• Permeation

Storing Groundwater: Rock Properties

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Porosity

• ​Rocks have tiny holes or empty spaces called pores within them.

• ​​Porosity measures the amount of this empty space in a rock.

• ​More empty space means the rock can hold much more water.

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Permeability

• ​Permeability is how easily water can move through a rock's pores.

• ​​Water can flow through when the tiny pores are well connected.

• ​Permeable rocks allow water to pass through them without much difficulty.

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Impermeability

• ​Impermeable rocks are layers that do not let water pass through.

• ​​This occurs when pores are not connected or the rock is solid.

• ​Water stops moving down when it hits an impermeable rock layer.

Multiple Choice

For an underground rock layer to store water, it must be:

• Porous and impermeable

• Dense and impermeable

• Porous and permeable

• Smooth and non-porous

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Aquifers and the Water Table

• The top underground layer is the unsaturated zone, not full of water.

• Below is the saturated zone, where all rock pores are filled with water.

• An aquifer is this saturated layer of rock that stores our groundwater.

• The water table rises with rain and falls during dry weather.

Multiple Choice

What is the name for the top of the saturated rock layer that rises and falls with rainfall?

• The aquifer

• The impermeable layer

• The unsaturated zone

• The water table

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Groundwater Movement and Collection

• Capillary action helps water move through porous materials, like from wet to dry soil.

• The amount of water that collects as groundwater in an aquifer is called recharge.

• Recharge is affected by climate, land slope, rock types, and land usage.

• Water that stays in an aquifer for thousands of years is called fossil water.

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Multiple Choice

Which of the following factors does NOT determine the recharge of an aquifer?

• The slope of the land

• The type of vegetation

• The age of the water

• The climate

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Common Misconceptions About Groundwater

Misconception	Correction
Groundwater exists as underground lakes and rivers.	It is held in small pores and cracks in soil and rock.
The water table is a flat and still surface.	Its level rises and falls, often matching the shape of the land.
All groundwater is clean and safe to drink.	It can be contaminated by pollutants from the surface.
Groundwater is an unlimited resource that will never run out.	It can be used up faster than it is replaced by rainfall.

Multiple Choice

What is the primary role of an impermeable rock layer in the formation of an aquifer?

• It allows water to move quickly through the ground.

• It helps the water to evaporate back to the surface.

• It filters impurities from the water.

• It acts as a barrier, preventing water from seeping deeper.

Multiple Choice

How would an extended period of drought affect the water table and an aquifer?

• The water table would fall, and the aquifer would have less water.

• The water table would remain the same, but the aquifer would shrink.

• The water table would rise, and the aquifer would fill up.

• There would be no effect on either the water table or the aquifer.

Multiple Choice

A city replaces a large forested park with a parking lot and several buildings. What is the most likely long-term effect on the groundwater in that area?

• The aquifer's recharge will increase because of faster water runoff.

• The amount of fossil water will increase.

• The aquifer's recharge will decrease because there is less permeable surface.

• The water table will rise significantly due to less water usage by trees.

Multiple Choice

A community relies on an aquifer that is known to contain 'fossil water'. Why might this be an unsustainable practice?

• The water has been there for thousands of years and is not quickly recharged.

• The water is too deep to be accessed with modern wells.

• Fossil water is non-potable and cannot be used for drinking.

• The water will cause excessive mineral buildup in pipes.

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Summary

• Groundwater is the world's largest accessible source of fresh water.

• Water seeps into the ground and is stored in layers called aquifers.

• An impermeable rock layer below an aquifer traps the water inside.

• The water table is the top of the saturated zone and its level can change.

• The process of refilling an aquifer with water is called recharge.

• Capillary action helps water move, and ancient groundwater is called fossil water.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4