Groundwater
Contents
Agenda for the Day ....................................................................................................................................... 2
Upper Anchor for Soil Water and Groundwater ........................................................................................... 3
Learning Progression Levels for Groundwater ............................................................................................. 4
Examples of Student Responses to Groundwater FAs.................................................................................. 6
Student Learning and Instructional Activity Table: Exploring Groundwater .............................................. 10
Exploring Groundwater Activity Sequence ................................................................................................. 11
Student Learning and Instructional Activity Table: Exploring Groundwater - Completed ..................... 12
Scientific Practices and Instructional Activities: Groundwater ............................................................... 13
Teacher Practices and Instructional Activities: Groundwater ................................................................ 15
Exploring Groundwater Activity Sequence ................................................................................................. 17
Activity 1: Permeability ........................................................................................................................... 21
Activity 2: Exploring With Groundwater Models .................................................................................... 24
Activity 3: Application Assessment: Where Would You Drill A Well?..................................................... 35
Activity 4: Get the Groundwater Picture ................................................................................................ 38
1
Agenda for the Day
Day #3 Groundwater
8:30
Loose ends from previous Day
8:45
Scientific Practices: Explanations and Argument
9:15


Introduction to groundwater
Student thinking about soil and groundwater
Upper anchor for soil and groundwater
9:45
Break
10:00 Groundwater Formative Assessments
 Version #1
 Version #2
11:00 Permeability Activity & Tools for Reasoning
 Pathways Tools
 Drivers and Constraints Tools
11:30 Lunch
12:15 Groundwater Models
1:45
Get the Groundwater Picture
2:45
Break
3:00
Continuation of Milltown Issue
4:00
School year project activities
4:30
Done
2
Upper Anchor for Soil Water and Groundwater
Structure of the Soil/Groundwater System: The soil and rocks undergrounds are
heterogeneous. There are different soil horizons and stratigraphic layers that have different
porosity and permeability values. Aquifers above impermeable layers (open to the surface) are
unconfined. Aquifers below impermeable layers are confined.
 Macroscopic to Microscopic Scale: Water underground is stored in cracks and small
spaces between sediment grains. When water fills the pore spaces completely, the
sediment is saturated. The top of the saturated zone is the water table.
o The capacity of geologic materials (e.g., soil, sandstone, shale) to hold water
is determined by the porosity of the material. Porosity is the volume of the
pore spaces and cracks. Smaller grain sizes have higher porosity (e.g., clay,
shale). Larger grain sizes have lower porosity (e.g., gravel).
o Permeability is a measure of the ability of a porous material to allow fluids to
pass through it. Permeability depends on the connectedness of the pore
spaces in materials. Larger sediment grain sizes (e.g., gravel, sandstone) =
higher permeability. Smaller sediment grain sizes (e.g., clay, shale) = lower
permeability. If water is able to flow (or be pumped) into and out of the
saturated zone of a material at a rate that is useable by people (i.e., if the
material is sufficiently permeable), it is called an aquifer. Impermeable layers
are called aquitards or aquicludes.
 Large (Landscape) Scale: Stratigraphic layers can cover great distances underground.
In unconfined aquifers, the top of the water table generally follows topography.
Therefore, surface water divides are usually also groundwater divides.
Processes in Watersheds: Water infiltrates into the small pore spaces between grains of
sediment or into cracks in crystalline rocks, displacing the air that is in those spaces. Water can
move through permeable materials in both horizontal and vertical dimensions. Water can leave
the soil/groundwater system where the water table intersects the surface, when wells pump
water from aquifers, by being absorbed into plant roots and transpired back into the
atmosphere, or where soil water is close to the surface, by being evaporated directly into the
atmosphere.
Scientific Principles: Water moves into, through, and out of the soil and groundwater system
according to scientific principles.
 Drivers:
o Gravity This force is the main driver in unconfined aquifers and is the reason why
in general, groundwater follows surface topography.
o Pressure (also called hydraulic head). This driver is important in confined aquifer
systems because the fluid pressure may be greater than gravity. Water moves
from areas of high pressure (high potential energy) to areas of low pressure (low
potential energy). This driver can move water in any direction, including pulling
water upwards in wells or pushing it upwards in artesian springs.
o At the microscopic scale, capillary forces are important. Adhesion between
organic material in soil and water molecules, and surface tension (cohesion
3

between water molecules) causes water within the small pore spaces to move
upwards or to dry surfaces.
Constraints: The rate and volume of infiltration is constrained by
o Permeability – Higher permeability results in higher infiltration.
o Porosity – Water will not infiltrate into saturated areas.
o Vegetative cover – More vegetation may slow down runoff and increase
infiltration rates.
Representations: Stratigraphy is represented on cross-sections. Soil and groundwater can be
modeled and represented using cross-section diagrams.
Dependency & Human Agency: Infiltration and aquifer recharge rates can vary from a few feet
a day to only inches per year. Therefore, in many areas, withdrawal of water from aquifers can
result in a drop in the water table.
Learning Progression Levels for Groundwater
Level 4: Model-Based Accounts
Level 4 accounts trace water into and out of the soil/groundwater systems at multiple scales
and along multiple pathways, include reference to driving forces and constraining variables that
define possible pathways for water underground, use representations such as cross-sections to
trace water, and consider implications of human connections to groundwater systems.
Level 3: School Science Accounts
Level 3 accounts tell school science stories about groundwater. They trace water into the soil
and eventually into groundwater or aquifers along multiple steps and pathways.
Structure & Systems: Accounts recognize that water underground is in pore spaces, although
the scale of these pore spaces may be too large or too small. They recognize that the
groundwater and surface water systems are connected, although accounts are more likely to
describe water infiltrating into the ground and are less likely to trace water from an aquifer into
surface water (e.g., a river) unless specifically prompted.
Scale: Can trace water underground at landscape scales. May not recognize scale of pore spaces
in underground systems.
Scientific Principles: Accounts usually names processes such as infiltration. They do not consider
how gravity, pressure, or permeability constrain water movements.
Representations: Can trace water through cross-sections, but do not usually reason about
constraining factors on groundwater flow. Thus, they may trace water through the
groundwater across watershed boundaries in unconfined aquifer systems even though this is an
unlikely path.
Dependency & Human Agency: Recognizes that human actions have impacts on environmental
systems. May reason that pumping from wells can impact the water level in aquifers. May not
recognize in principled ways the limitations of human agency.
Level 2: Force-Dynamic Accounts with Mechanisms
Compared with level 1, level 2 accounts show an expanded awareness of and experience with
the physical world. These accounts provide more sophisticated force-dynamic explanations and
4
predictions about water. Most significantly, mechanisms to move water or change water are
included (compared with level 1, in which no mechanisms are included).
Structure & Systems: Level 2 pictures show water in open spaces underground, such as in
underground rivers, lakes, or caverns. Often depicts wells as the iconic stone cylinder with a
bucket and rope (Jack & Jill well). May not recognize how surface and groundwater systems
interact.
Scale: Focus is on visible macroscopic scale at familiar distances.
Scientific Principles: Includes mechanisms for water moving into the soil or ground. Mechanisms
describe agents (often inanimate things in natural systems) doing something to the water, such
as the ground absorbing the water. Accounts may also describe natural tendencies of water
(sinking into the ground) or describe familiar experiences, such as water and dirt will make
mud. Accounts may refer to special circumstances, such as groundwater may get into a bathtub
if the bathroom is in the basement. For example, river water can enter a well if the river
overflows into the top of the well.
Representations: Recognizes limited connections between representations and the physical
world. For example, reasons about maps in two dimensions (horizontal) but does not consider
the third (vertical) dimension. May describe cross-sections.
Dependency & Human Agency: Humans benefit or are impacted by movements of water
underground if the conditions are right.
Level 1: Force-Dynamic Accounts
Level 1 accounts of water focus on water in visible systems at macroscopic scales. At this level,
accounts explain that water goes into the ground, but once that water is no longer visible, the
water is considered to be gone, or to have essentially disappeared.
Structure & Systems: Drawings of underground systems tend to depict water in tanks or pipes
only. They provide anthropocentric sources for groundwater, such as from toilets or sewers.
Scale: Accounts focus on macroscopic, visible water or water in familiar places.
Scientific Principles: Accounts do not trace water into other systems. Accounts may say that
water “goes” into the ground, but do not say how or what happens to the water once it gets
there. Typically, the view is that water that goes underground is not re-available for use.
Representations: Drawings of water underground show water in pipes or tanks.
Dependency & Human Agency: These accounts portray people as the sources and movers of
water underground.
5
Examples of Student Responses to Groundwater FAs
Student Drawing
Level
Notes on levels or
foci for instruction
1
V1
2
V2
6
3
V1
4
V1
7
5
V2
V2
6
8
7
V2
8
V2
9
Student Learning and Instructional Activity Table: Exploring Groundwater
What students need to work on (Foci
for instruction)
Permeability
Groundwater Models &
Where to put a well
Get the Groundwater
Picture
Structure &
Systems:
Scale
Scientific
Principles
Representations
Dependency &
Human Agency
10
Exploring Groundwater Activity Sequence
Activity/Description
Learning Goals – Practices fused
with content
Formative
Assessments
Drivers &
Constraints
Representations
Tools
Permeability
-
Groundwater 1
Groundwater 2
-
- Gravity pulls water
down;
- Permeability
constrains infiltration
rates
Physical models
Students pour water into
cups of gravel, sand, and
clay to see what happens
to the water.
Exploring with
Groundwater Models
Investigate and analyze and
interpret data about permeability
Construct explanations for
groundwater infiltration rates
- Drivers & Constraints
tool to reason about
permeability rates
Use models to explore groundwater
systems
Investigate and analyze and
interpret data from wells
Construct explanations about water
movements in groundwater
systems
Investigate and analyze and
interpret data about wells
Construct arguments from evidence
about where to locate a well
Groundwater 1
Groundwater 2
- Physical models
- Cross-section
diagrams
- Drivers and
Constraints tool to
reason about possible
pathways for water
underground
Cross-section
diagrams
- Drivers and
Constraints tool to
reason about possible
pathways for water
underground
Use cross-section representations
to locate and trace water in the
groundwater system
Analyze and interpret well log data
to predict groundwater movements
Construct predictions for water
movements through a groundwater
system
Groundwater 1
Groundwater 2
- Gravity pulls water
down; pressure
pushes water to
areas of low pressure
- Permeability
constrains infiltration
rates
- Gravity pulls water
down; pressure
pushes water to
areas of low pressure
- Permeability
constrains infiltration
rates
- Gravity pulls water
down; pressure
pushes water to
areas of low pressure
- Permeability
constrains infiltration
rates
Cross-section
diagrams
- Drivers and
Constraints tool to
reason about possible
pathways for water
underground
-
Students use groundwater models to investigate
groundwater movement
Where would you put a
well?
Given a map/crosssection, students are
asked to suggest a
location for a new well
-
Get the Groundwater
Picture
-
Students use well data to
construct a cross-section
and then use the crosssection to analyze the
groundwater system.
-
Groundwater 1
Groundwater 2
11
Student Learning and Instructional Activity Table: Exploring Groundwater - Completed
What students need to work on (Foci for
instruction)
Permeability
Groundwater Models &
Where to put a well
Get the Groundwater
Picture
Investigate location of
water in different
sediments (L2 to L3)
Investigate and trace
movement of water through
underground systems (L2 to
L3 and L3 to L4)
Trace water through
underground systems (L2 to
L3 and L3 to L4)
Examining the size of
pore spaces and the
influence on
permeability rates (L2 to
L3 and L3 to L4)
Investigating water
movements through pore
spaces at the macroscopic
scale (L2 to L3 and L3 to L4)
Tracing water through
underground systems at
landscape scales (L2 to L3)
Recognizing that water exists in cracks and pore
spaces (L2 to L3)
Structure &
Systems:
Scale
Recognizing connections between surface and
soil/groundwater systems (L2 to L3 and L3 to
L4)
Describing groundwater systems at landscape
scales (L2 to L3)
Recognizing scale of pore spaces in
underground systems (L3 to L4)
Moving from force-dynamic agents to processes
of infiltration to describe water movements (L2
to L3)
Scientific
Principles
Representations
Dependency &
Human Agency
Moving from naming processes to considering
drivers (gravity & pressure) and constraints
(permeability) on processes to move water in
underground systems (L3 to L4)
Using cross-sections to trace water in
underground systems ( L2 to L3)
Reasoning about drivers and constraints from
cross-sections (L3 to L4)
Recognizing how humans impact and are
impacted by movements of water underground
(L2 to L3)
Recognizing the limitations of the groundwater
system to provide fresh water (L3 to L4).
Investigate permeability
of different sediments
(L2 to L3 and L3 to L4)
Using scientific principles to
explain water movements
and to predict the best
location of a well (L2 to L3
and L3 to L4)
Writing Accounts (Explaining
& Predicting) of water
pathways (L2 to L3 and L3 to
L4)
Tracing water through
underground systems (L2 to
L3)
Considering the influence of
gravity, pressure, and
permeability to trace water
through underground
systems (L3 to L4)
Writing Accounts (Explaining
& Predicting) of water
pathways (L2 to L3 and L3 to
L4)
Drawing cross sections and
using cross-sections to
explain, predict, and make
arguments (L
Using cross-sections to trace
water and explain, predict,
and make arguments about
water flow (L2 to L3 to L4)
Using cross-sections to
explain and predict
groundwater movements
and well locations (L2 to L3
to L4)
Using cross-sections to trace
water and explain, predict,
and make arguments about
water flow (L2 to L3 to L4)
12
Scientific Practices and Instructional Activities: Groundwater
Using Models
Practices
Investigating,
Analyzing,
Interpreting
Data
Constructing
Explanations
Arguments
From Evidence
(& Social
Construction)
What Students Need to
Work On (Foci for
Instruction)
Using models to develop
understanding of an
otherwise invisible system
(i.e., groundwater).
Permeability
Groundwater Models & Where
Would You Put Well
Get the Groundwater
Picture
Using models to develop
understanding of particle
size, permeability, and
water movement.
Using first-hand
experiences with models of
sediments and the
groundwater system to
explore, analyze &
interpret how water flows
through the ground.
Moving from forcedynamics & informal rules
to considering drivers
(gravity, pressure) &
constraints (permeability,
statigraphy) to explain
movement of water in
ground.
Developing, defending &
evaluating arguments &
explanations using
experience, evidence &
scientific principles in social
context (i.e., peer to peer).
Testing with different
sediment/particle sizes to
investigate permeability
through different
materials.
Using groundwater models to
explore this system. Drawing
and interpreting cross-section
diagrams of groundwater
system.
Interpreting observations/data
of pumping in a groundwater
model to make inferences
about locations of hidden well
bottoms.
Analyzing cross-section to
decide where to build a well.
Using D&C Tool to explain how
gravity and pressure drive
groundwater and how
permeability and statigraphy
constrain groundwater.
Applying explanations in
“Where would you put well?”
assessment.
Developing, sharing, defending,
and evaluating with peers
arguments about where well
bottoms are located and where
to build well.
Constructing crosssection of groundwater
system to develop
understanding of
groundwater flow.
Students us well data to
construct a crosssection and then use
the cross-section to
analyze the
groundwater system.
Using D&C Tool and
constructing explanations
about drivers and
constraints that govern
permeability of different
materials.
Sharing permeability
explanations with peers.
Students can construct
explanations of where
water flows in the
represented crosssection.
13
Cross-Cutting Concepts
What Students Need to Work
On (Foci for Instruction)
Permeability
Scale,
Proportion &
Quantity
Relating size of sediment
particles to permeability, and
permeability to groundwater
movement.
Investigating how size of
sediment relates to
permeability.
Systems &
System
Models
Developing understanding of
groundwater system (which is
usually invisible to us).
Examining groundwater
system materials in
macroscopic scale model,
which can then be
extrapolated to larger scale
groundwater systems.
Flow &
Conservation
of Matter
Tracing water into, through and
out of the groundwater system.
Examining water flow through
different sediment sizes.
Stability &
Change
Recognizing how groundwater
is recharged and how natural
events (e.g., drought) and
human actions (e.g., pumping
of groundwater) can change
the amount of groundwater
that is available.
Examining how quickly water
can be infiltrated or extracted
from different sediment types.
Groundwater Models &
Where Would You Put
Well
Developing understanding
of size of pore spaces
underground (generally
not large open lakes or
rivers).
Developing understanding
of the structure of
groundwater systems
using a small-scale model.
Connecting structure of
groundwater systems to
how water flows into,
through and from
groundwater system.
Examining how pumping
of groundwater can
impact amount and
movement of water in
groundwater system.
Get the Groundwater
Picture
Translating between
scale of cross-section
diagram and scale in
real world.
Developing
understanding of the
structure of
groundwater systems
through constructing
and using a crosssection diagram.
Using a cross-section
diagram to consider
groundwater flow
through different
materials.
Examining how
groundwater system
can change through
actions such as
pumping and/or
introducing pollutants.
14
Teacher Practices and Instructional Activities: Groundwater
Permeability
Formative Assessment
Tools for Reasoning
Supporting Explanation
Social Construction of
Understanding
Groundwater Models & Where
Get the Groundwater Picture
Would You Put Well
Groundwater Formative Assessment Use this formative assessment to identify students’ initial ideas about what
the groundwater system looks like and how water moves through the groundwater system. Some students may
think groundwater exists in underground pipes or tanks (level 1) or in open areas underground such as
underground lakes or rivers (level 2). Some students may think that groundwater is a dead end where water goes
and never comes out (level 2). The Student Learning and Instructional Activities table on p. 12 provides ideas for
using the activities to support students to develop understandings related to this formative assessment. Further
suggestions are also provided in the formative assessment teacher materials.
Use the D&C Tool to help students
Use the D&C Tool to help
Use Pathways Tool to help students
reason about drivers and constraints students explain drivers (gravity, develop understanding of multiple
that govern how water moves
pressure) and constraints
pathways into, through, and out of
differently through different types of (statigraphy, permeability) for
groundwater system.
sediment.
how water moves into, through
and out of groundwater system. Use D&C Tool to help students consider
drivers and constraints acting on
different layers of the groundwater
system.
Use the Drivers & Constraints Tool and application questions in activities (e.g., Where would you build a well?) to
press students to not just DESCRIBE WHAT will happen, but to also EXPLAIN HOW AND WHY events and
processes in groundwater systems happen.
Use participatory and collaborative teaching strategies to engage students in co-constructing their understanding.
 When you use formative assessment at the beginning of a unit or lesson, allow students to share their
different ideas about “what, how and why” questions, but do not give the correct answers at this point. Write
down different students’ ideas in a public place so they can be revisited throughout the unit (e.g., during
investigations and further development of explanations).
 During investigations and other activities, have students work in small groups first to share their ideas and
construct their explanations. Students may feel more comfortable sharing ideas if, initially, they are not asked
to share in front of the whole class. Working in small groups, students also have the opportunity to learn from
each other, and not just from the teacher. They also have the opportunity to question each other’s ideas.
 After students have worked in small groups, provide opportunities for groups to share their ideas and
explanations with the whole class (e.g., completed tools, written explanations for application questions). If
15

possible, use a document camera or other way to display groups’ responses so they can be seen by the whole
class. Rather than evaluating students’ answers as the teacher, ask the students to consider and evaluate each
others’ ideas and explanations. Do they agree or disagree? Why? Encourage students to be respectful when
they disagree.
Scientific argumentation is a central practice that scientists engage in every day. Providing opportunities for
students to engage in scientific argumentation with peers supports development of a core scientific practice.
Students learn that science is not just a body of facts to be learned from a textbook or a teacher. Rather,
science is a process of learning about the world that scientists engage in together as a collaborative and critical
community.
16
Exploring Groundwater Activity Sequence
Summary of Activities
Activity 1: Permeability
Students pour water into cups of gravel, sand, and clay to see what happens to the water. This
activity is similar to Part I of the “Get the Groundwater Picture” activity in Project Wet.
Activity 2: Exploring With Groundwater Models
Students use groundwater models to investigate groundwater movement through different
sediment types and gain knowledge of how wells impact water resources.
Activity 3: Well Problem – Where would you put a well?
Given a map/cross-section, students are asked to suggest a location for a new well and justify
their answer based on the features on the map and cross-section.
Activity 4: Get the Groundwater Picture
Students use well data to construct a cross-section and then use the cross-section to analyze
the groundwater system.
Learning Goals
These activities help students explore the following questions.
1. Where is water underground?
2. How does water get into the ground and what affects how much water infiltrates into
the ground?
3. How does water move underground? How does water move out of the ground?
4. How deep is the well (investigation question)?
5. Where should you put a well?
Scientific Practices with Content
1. Students will ask questions about groundwater structure and processes.
2. Students will use models of groundwater systems to investigate structure and processes
in groundwater, including driving forces and constraining factors that govern how
groundwater moves.
3. Students will analyze and interpret data about the permeability of different substrate
materials and impacts of well pumping on different places within a groundwater system.
4. Students will construct explanations for groundwater processes including infiltration,
groundwater flow, and well pumping using understanding of groundwater structure,
driving forces of gravity and pressure, and the constraining factor of permeability.
5. Students will make arguments from evidence about where hidden well bottoms are
located based on observations of two different wells pumping water. Students will also
make arguments from evidence about where the best place to build a well is given a
cross-section scenario problem.
6. Students will evaluate each other’s arguments about groundwater scenarios and
communicate their own arguments.
17
Crosscutting Themes
1. Students will observe patterns in type of substrate material and level of permeability to
make inferences about how groundwater system processes will work in particular
contexts.
2. Students will understand that there is a causal relationship between human pumping at
the surface and the level of the water table below the ground.
3. Students will understand the role of scale of particle size in impacting permeability, and
apply this relationship to explaining groundwater flow in large-scale groundwater
systems.
4. Students will develop understanding of groundwater as a system connected to the
surface water systems using physical system models.
5. Students will develop understanding of groundwater flow through explorations with
models.
6. Students will develop understanding of groundwater system structure and function
through exploration with models.
7. Students will develop understanding of how human actions can change the quantity of
groundwater present in aquifer systems.
Elements of the Learning Progression
1. Structure of Systems: Structure of the soil/groundwater system
2. Scale: Macroscopic (but hidden) to landscape
3. Scientific Principles
Drivers
Gravity – Water infiltrates downward into the ground due to the pull of gravity.
Pressure – Water moves from areas of high to low pressure underground. Wells work
by changing pressure within the well shaft. In the case of shallow wells (less than 20
meters deep), wells work by decreasing pressure at the top of the shaft, so that water
moves from an area of higher pressure down below, to an area of lower pressure at
surface. In the case of deep wells (greater than 20 meters), well pumps use a
compressor to increase pressure at the bottom of the well, which results in water
moving to the area of lower pressure at the surface.
Capillary action – Water will move upwards through small spaces between sediment
particles. Capillary action works through a combination of surface tension caused by
cohesion within the water and adhesion of water molecules to sediment particles.
Note: You may not want to address drivers of pressure and capillary action with
students operating at levels 1 and 2 on the learning progression. Focus on gravity as
the driver with these students, and consider pressure and capillary action with students
who show readiness to move from level 3 to level 4.
Constraints
Permeability – Permeability is a measure of the ability of a porous material (such as
unconsolidated sediments underground) to allow fluids to pass through it. Gravel is
more permeable than sand. Clay and shale are not very permeable, such that for
practical purposes they are impermeable (do not allow fluids to pass through).
Groundwater movement is thus constrained by permeability of the material that the
18
water is moving through. Water generally moves much more quickly through
permeable substrates such as gravel, and more slowly through substrate materials
that are less permeable.
4. Representations
Cross-section diagrams
5. Human Dependency and Change: The volume of groundwater available for use is
limited. People may pump water from the ground faster than it can recharge, effectively
mining the water. Changes in surface cover can change the permeability of the ground,
limiting infiltration and recharge rates. People can also pump water into the ground to
store water for later use.
Formative Assessments
Use Groundwater Formative Assessments #1 and #2 to assess student level of achievement for
understanding structure of the groundwater system and pathways of water underground.
1. Hold up a glass of tap water. Explain that in some communities (maybe your
community), the tap water comes from underground.
2. Ask students to think for a minute about how it could be possible that people can get
water from the ground. What does it look like underground? Where is the water? How
does the water get underground? How do people get the water out of the ground?
3. Distribute a Groundwater Formative Assessment sheet to each student and have
students complete it.
Target Explanations and Reasoning
Where is water underground?
The soil and rocks underground are heterogeneous. There are different soil horizons and
stratigraphic layers that have different porosity and permeability values. Impermeable layers
are called aquitards or aquicludes. Water underground is in pore spaces and cracks. Aquifers
above impermeable layers (open to the surface) are unconfined. Aquifers below impermeable
layers are confined.
How does water get into the ground and what affects how much water infiltrates into the
ground?
Water infiltrates into the ground because gravity pulls water down. The water infiltrates into
the pore spaces between grains of sediment or into cracks in crystalline rocks, displacing the air
that is in those spaces. The volume of water that can infiltrate into and out of the soil and
groundwater is determined by the connectedness of the pore spaces (permeability). Larger
sediment grain sizes (e.g., gravel, sandstone) have higher permeability. Smaller sediment grain
sizes (e.g., clay, shale) have lower permeability.
How does it move underground? How does it get out of the ground?
Water moves underground in response to gravity and pressure. In unconfined aquifers, water
moves downwards in response to gravity. In confined aquifers, water moves from areas of high
pressure to areas of low pressure. Water leaves the underground system into a lake, river, or
spring when an unconfined aquifer intersects the ground surface. Water can also leave either
an unconfined or confined aquifer when pressure in a well draws the water upwards.
19
Which Well is Deepest?
Well B is shallower because eventually it pulls out blue water from the lake. Well B is in the
unconfined aquifer. Water from the lake infiltrates into the unconfined aquifer because gravity
pulls it downwards. As well B is pumped, it creates a zone of low pressure and the water in the
well moves upwards. This situation then creates low pressure at the bottom of the well and
water from the aquifer moves into the well. Since the unconfined aquifer connects to the lake,
pumping from this well eventually pulls water from the lake into the well. Well A does not pull
out blue water. The reason is because the well is in the confined aquifer, which is below an
impermeable layer. When water infiltrating down from the lake meets the impermeable clay
layer, it cannot move through the clay because the pore spaces in the clay are so small that the
water does not move through quickly. Therefore, the water from the lake cannot infiltrate into
the gravel below. Pumping from well A does not affect the lake.
Where would you put a well?
A well next to the house above the impermeable layer will be cheapest to drill because it will be
shallow. A well in this location will be susceptible to running dry because some of the recharge
area is covered by the impermeable Cherry Lane pavement. A well near the house but below
the first impermeable layer or a well near the river will have a more reliable recharge from the
river. If the well is close to the river, it may have contamination problems from the river. A well
near the house into the lowest gravel layer will be most expensive. It will be least susceptible to
contamination. However, recharge may be very slow, if at all, and the well could be susceptible
to going dry.
20
Activity 1: Permeability
Summary of Activity
Students pour water into cups of gravel, sand, and clay to see what happens to the water. This
activity is similar to Part I of the “Get the Groundwater Picture” activity in Project Wet.
Materials
For each group:
 1 clear plastic drinking cup filled with gravel
 1 clear plastic drinking cup filled with powdered clay
 1 clear plastic drinking cup filled with play sand
 1 plastic cup of water
 3 eye droppers or plastic pipettes with narrow tips.
 Graduated cylinder for water or another cup with approximately 20 ml marked on the
side.
For each student:
 Science notebook and pencil
 Drivers and Constraints Tool in student pages below
Activity Procedures
Question: Establish a question and elicit student ideas
1. Divide students into groups of 3 to 4 and provide each group with 1 cup of gravel, 1 cup of
sand, 1 cup of clay, 1 cup of water, 3 additional cups with 20 ml marked on the side of each,
and 3 pipettes. If graduated cylinders are unavailable, provide another plastic cup or beaker
with approximately 20 ml marked on the side of the cup.
2. Have students pour 20 ml of water into each of the empty plastic cups.
3. Explain to students that they will be pouring 20 ml of water into each sediment cup. Before
they pour the water into the cups of sediment, have students write in science notebooks
and share with their group their initial ideas about the following questions.
a. In which cup will the water infiltrate (soak in), the fastest? Why?
b. In which cup will it be easiest to get water out? Why?
Explore & Investigate: Explore patterns in phenomena
4. Have students pour 20 ml of water into each sediment cup. You may direct
Practices
students to pour the water on all cups at the same time.
Using Models
5. Have students observe where the water goes in each cup and record their
observations. Prompt students to make careful drawings of the water in the
pore spaces in each of the three sediment cups. Support students in seeing
the pattern that the larger the grain size of the sediment, the faster the
Practices
water moves through.
Analyzing &
Interpreting
6. Have students use the pipette to try to pull water out of each of the three
Data
cups of sediment. Which cup is easiest to pull water out of? Why? Support
students in noticing the same pattern – the larger the grain size the easier it
is to pull water out of the cup.
21
Explain: Introduce scientific ideas and explain patterns
7. Introduce the term infiltrate - to move into and through.
8. Define permeability - how easily water moves through the pore spaces. Permeability is
relative. Gravel has a greater permeability than sand. Clay and shale have a very low
permeability, to the point that for practical purposes, they are impermeable.
9. If necessary provide the following analogy: Imagine a room filled with beach balls. How
much space is between the beach balls? Would water flow through these spaces easily?
We would say this room is permeable. Now imagine a room filled with golf balls. How much
space is between the golf balls? It would be harder for the water to flow through the golf
balls. We would say this room is less permeable than the room with beach balls. Now,
imagine a room filled with ball bearings. There is still space between the ball bearings, but
they are very, very tiny. It would be much harder, and take much longer for the water to
flow through the ball bearings than the beach balls. This room would be even less
permeable. If the room was filled with clay or concrete, water would not flow through the
room, and the room would be impermeable.
10. Have students return to their initial ideas about in which cup the water would infiltrate the
fastest. Support students in recognizing the pattern that water infiltrates (i.e., moves
through) into sediment with larger pore spaces faster than sediment with smaller pore
spaces. Sediments with larger pore spaces are more permeable than sediments with smaller
pore spaces.
11. Have students, in their groups, complete the Drivers and Constraints Tool shown below.
After groups complete their tools, engage the class in a discussion to ensure students
understand the role of gravity as a driver and the role of permeability as a constraining
factor in water moving through different materials. Students should also understand the
pattern in permeability levels for sand, gravel and clay.
12. Assign each group one of the following questions to construct an
explanation about using claims, evidence and reasoning. Make sure
Practices
each of the questions is addressed by at least one group. After
 Constructing
students complete their explanations, have them share with the class
Explanations
and check to make sure all students understand and are able to
explain the patterns using claims, evidence and reasoning.
 Making
a. Which type of material does water flow through the fastest?
arguments
from
Water moves through gravel the fastest. As gravity pulls water
evidence
down, it moves quickly through the gravel because gravel has
the largest and most connected spaces between particles for
water to move through.
b. Which type of material does water flow through the slowest?
Water moves through clay the slowest. The clay has the
smallest and least connected spaces between particles. Water
does not move through these spaces very quickly (Note: clay
also has adhesive properties that hold the water in place as
well)
22
Students can complete this activity using their science notebooks and the Drivers and
Constraints Tool (example included below).
23
Activity 2: Exploring With Groundwater Models
Summary of Activity
Students use groundwater models to investigate groundwater movement through different sediment
types and gain knowledge of how wells impact water resources.
Materials
For class:




Document camera
LCD projector or SmartBoard
Half a cup of water with two drops of blue food coloring in it
One groundwater model for initial demonstration
For each group:





A groundwater model
A container labeled “storage tank” to pump water into (e.g., recycled plastic lettuce bin)
A rain cup (paper cup with holes punched on bottom for raining on model)
A beaker or small container of water
Water source (sink or jug of water)
A rag or reusable towel available for spills

For each student:



One blank Drivers and Constraints Tool
One “Exploring With Groundwater Models” handout
Pencil
Activity Procedures
Question: Establish Questions and Elicit student ideas
Part 1 (Day 1)
1. Before class begins, write the four questions in procedure 3 below in four columns on the
whiteboard.
2. Begin class with a short review of the permeability activity. Ask students:
a. What did they find out about sand, gravel and clay?
b. What did their investigation with sand, gravel and clay have to do with
groundwater?
3. Next review students’ ideas about groundwater using the questions written on the board in
a whole class discussion. Ask multiple students to share their ideas for each question.
Record students’ ideas on whiteboard as they share.
a. What does it look like underground where there is water?
b. How does water get into the ground?
c. How does water move underground?
d. How can water get out of the ground?
4. Put students into groups of four and give one “Exploring With Groundwater Models”
handout to each student.
5. Set a groundwater model at the front of the class. The model should be prepared so that
the lake in the center is partially filled. Have each student draw the cross section of the
groundwater model on page 1 of their handout. Explain to students how the fold line works
24
and how they should draw what they see from a top view in the top part of the box, and
how they should draw what they see in the cross-section view in the bottom part. Students
can come to the front of the class to see the model more closely, including both the side
and the top. Students should label on their drawings: different layers of material, the wells
(in top view only), the lake from top and side, and water they see in the model.
Group Work with Drivers and Constraints Tool and Pathways Tool – Where will water go?
6. Establish the question: Where does water go?
7. Have students make predictions about where, how, and why water flows in the model.
Show students the rain cup and explain that soon there will be a rain storm over the
ground. Ask students to use the Drivers and Constraint Tool to predict where they think the
water will go. Encourage students to think about drivers (gravity, pressure) and constraints
(permeability). Have students write their predictions, including reasons, on the back of their
completed tool
8. Have students share their predictions.
9. Students may also use the Pathways tool to make their predictions about where the water
will go.
10. Establish the driving question: Which well goes deepest? Students may make initial
predictions.
11. Next, conduct the first investigation with the groundwater models as a
Practices:
demonstration that students need to reason about in their small groups.
Using
Note that students will not know where the bottom of the two well tubes are
Models
located, and will need to figure this out based on the demonstration. The
teacher should know, though, that the wells are configured as shown in the
diagram below.
25
Explore & Investigate: Explore phenomena for patterns
12. Show students the water with blue food coloring and tell them that this water represents
the most recent rain. Pour the water into a rain cup and rain over the groundwater model,
making sure some of the tinted water gets in the lake. Tell the students that each of the two
wells (A and B) is a solid tube that’s open at the bottom with a filter over it. Show students
an example of a well tube with a nylon filter over it. Tell students that you are going to
pump 12 times from each well pump. Based on their observations from the pumping,
students will need to decide in which layer they think the bottom of each well is located.
13. Ask students to observe carefully as you conduct the investigation. First,
Practices:
pump 12 times from Well A into the storage container. The water that is
 Analyzing &
pumped out should remain clear. Show students the clear water. Dispose of
Interpreting
the water from the storage container. Next pump 12 times from Well B. The
Data
water that is pumped into the storage container should have some blue tint
 Constructing
to it. Show the blue-tinted water to the students. Based on this observation,
Arguments
from
in their small groups, students should develop arguments for where they
Evidence
think the bottoms of Well A and Well B are located. Ask students to complete
page 2 of their handouts.
14. Next tell students that each group will get a groundwater model to work
Practices:
with. Ask students what they should remember when working with the
Using Models
models (e.g., they’re fragile and should be used with care, pump the wells
gently, allow each student a chance to explore with the model, etc.). Next
pass out a groundwater model, storage tank, rain cup, container of water,
26
and rag to each group. Students should explore with their model for about 10
minutes and complete the questions on page 3 of their handout.
15. Collect student handouts and review before second part of lesson on next day.
Part 2 (Day 2)
Explain: Introduce Scientific Ideas and students explain patterns
Review Cross-Section Diagram and Introduce Terms
1. Write following terms on board:
a. Permeability
b. Infiltration
c. Groundwater flow
d. Water table
e. Unconfined aquifer
f. Confined aquifer
2. Return students’ handouts and project the cross-section diagram WITHOUT WELLS on the
next page onto the Smartboard, or draw a similar diagram on whiteboard. Students have
their diagrams on their handouts to look at and refine.
3. Review permeability with students. Draw pictures of sand, gravel, and clay particles on
board. Define permeability as the ability of a material to allow fluid to pass through. Talk
about water residing and passing through spaces between particles of sand, gravel and clay.
Ask whether clay is permeable at all? (Maybe just a tiny bit --- it does get wet).
4. Revisit with students what it looks like underground where there is water. Check their ideas
after exploring with the models. Are there open lakes and streams? Where is MOST of the
water underground?
5. Revisit how water gets into ground. Ask them to explain what they observed and provide
the term infiltration for water soaking from the surface into the ground.
6. Ask students to describe how water moves underground based on their observations. They
should describe that it moves between pore spaces in sand, gravel and clay. This is called
groundwater flow.
7. With a marker, draw in the lake and extend surface of lake line to left and right to show
height of water table (see drawing from Where Would You Drill a Well? assessment for an
example of how to draw in water table). Explain to students that the line you drew in is the
water table and that that’s the same height as the surface of the lake. Students should draw
and label the water table on their own diagrams. Help students understand that below the
water table, the ground is saturated with water. Ask the students to talk about how the
level of the water table changed during their explorations the previous day.
8. Next explain to students that the area with water in sand and gravel above the clay layer in
the model is an unconfined aquifer. An unconfined aquifer is a layer with water that is not
below an impermeable layer. Ask the students where the impermeable layer is and how
they know (the clay, because water does not move through clay easily). Label the
unconfined aquifer on the diagram and have students label the unconfined aquifer on their
own diagrams.
27
9. Next explain to students that the area below the clay layer is a confined aquifer. A confined
aquifer is a layer with water that is below an impermeable layer. Label the confined aquifer
on the diagram and have students do the same on their own diagrams.
10. Ask students if they have any questions about the diagram or what the water table is, or
what a confined aquifer and an unconfined aquifer are.
Sharing Student Explanations About Well Bottom Locations
1. Note: Students will make and support claims and agree or disagree with each
other’s claims. Remind students that they can disagree with someone in a
polite way. Scientists participate in arguments about science all the time to
Practices
work together to learn how the world works. It’s not about being smarter
Making
than someone else. Ask students to please be considerate when they share
Arguments
their ideas and when they disagree with another student.
from Evidence
Communicate
arguments
Evaluate
arguments
2. Call on a group to come to front of class and draw on the projected diagram
how far they think Well A extends down into the ground. The group should
explain why they answered the way they did. Ask the rest of the class to
agree or disagree by showing thumbs up or thumbs down. If any students
disagree, ask them to explain why. Lead a discussion of student ideas (with
students responding to each other’s ideas, rather than only having teacher
evaluate students’ ideas) and help students come to consensus. Students
should understand that Well A is a deep well that extends into the confined
aquifer. Because it is mostly separated from the lake by the impermeable
layer of clay, pumping from Well A does not have much effect on the lake.
3. Next, call on another group to come to the front of the class and draw on the
projected diagram how far they think Well B extends down into the ground.
The group should explain why they answered the way they did. Ask the rest
of the class to agree or disagree by showing thumbs up or thumbs down.
Lead a discussion of student ideas and help students come to consensus.
Students should understand that Well B is a shallow well that takes water
from the unconfined aquifer above the clay layer. Because it is NOT
separated from the lake by an impermeable layer, pumping from Well B has
a significant impact on the level of the water in the lake. This discussion
should help students understand how groundwater is connected to surface
water.
Groups Work on Drivers and Constraints Tools
1. Hand out one blank Drivers and Constraints Tool to each student.
2. Project Drivers and Constraints Tool. Discuss what the aspects of the tool mean and how to
use.
a. Drivers are forces that move water. Use example of water on a hill that starts on
the side of the hill. If it goes over the ground, which direction will it move?
(Down). What’s the force that moves it? (Gravity). The name of this is runoff.
28
b. Constraints are things that limit how or how much something happens. So your
parents may limit how much TV you can watch. That’s a constraint. And the law
limits you from driving until you’re sixteen. That’s a constraint. With water,
constraining factors limit how fast or slow, how much, or in which direction
water moves. Use slope as an example. Draw a steep slope and a shallow slope
on the board and ask students how these two slopes will affect how fast or slow
water moves. Then draw two slopes slanting in different directions and ask
students how these two slopes will direct which direction water moves.
c. Next go through an example of a row of the Drivers and Constraints Tool as a
class --- use water in sand layer to water in a gravel layer.
3. Students should now return to their lab groups to work together on the Drivers and
Constraints Tool.
4. Show the following options for rows of the Tool to think about and work on. Each group
should pick two options and use those options to work on two rows of the Tool.
a. Water on the surface (above the ground)  Water in unconfined sand layer
b. Water in unconfined sand layer  Water in unconfined gravel layer
c. Water in unconfined gravel layer  Water in clay layer
d. Water in unconfined sand layer  Water in the lake (this one is more
challenging)
e. Water in the ground  Water being pumped out of a well (If you’d like, talk
about pumping and pressure using the balloon demo*)
f. Choose a different starting and ending place
Example Drivers and Constraints Tool responses for teachers are provided on the next page.Example
Responses to Drivers and Constraints Tool
29
30
*Balloon Demo For Explaining How Wells Work: Students may have trouble explaining drivers and constraints
for how water comes out of a well. Use this balloon demo to help students think about pressure and movement
of matter, including water. Fill a balloon with some air and squeeze the end shut so the balloon remains
somewhat full. Hold up the balloon and ask students what is the difference between the air inside the balloon
and the air outside the balloon (students should be able to describe that the air inside the balloon is more
compressed, and that the molecules of air are closer together)? Next, ask the students if they think there is
higher pressure inside or outside of the balloon (students should be able to describe that there is more pressure
inside the balloon)? Ask the students what they think will happen if you let go of the end of the balloon --- will
air move from inside the balloon out or from outside the balloon in? Why? (Students should be able to explain
that air will move from inside the balloon out and they should have some ideas to share about why). Release the
balloon and allow students to observe that air moves out from the balloon. Next, ask students to apply their
explanation to the question of whether matter moves from areas of low pressure to high pressure or from areas
of high pressure to low pressure. (Students should reason that matter tends to move from areas of high
pressure to low pressure because that is what they observed with the balloon. They may indicate that
the molecules of air are pushing against each other.). Finally, ask students to apply what they observed
to think about how a well works. The basic idea is that well pumps change the pressure within the well
tube so that there is higher pressure at the bottom of the well under the water table and lower
pressure at the surface. Because matter moves from areas of high pressure to low pressure, the driver
of pressure overcomes the driver of gravity and the water moves up to the surface where it can be
used. You can let students know that constraining factors for this process of well pumping include
things like the depth of the water table (it takes more pressure to move water a further distance to the
surface) and the power of the well pump (a stronger pump that creates more pressure at depth can
move water to the surface more rapidly than a pump that creates less pressure at depth).
Whole Class Discussion of Drivers and Constraints Tools
1. Lead a class discussion with groups reporting out their responses for the Drivers and
Constraints Tool. Project the completed Tools using a document projector, or have
students write their responses for a row on the whiteboard. Discuss one row at a
Practices
time. Use the agree/disagree (thumbs up/thumbs down) strategy to have students
Communicate
& Evaluate
argue about their claims. Make sure you ask students to discuss the reasons for their
Arguments
responses and what evidence they saw that led to their responses. See the sheet in
the supporting materials for some suggestions of what reasonable responses might
look like for the different options. Help students move toward understanding the
Drivers and Constraints for these pathways.
2. Students can edit their responses to the Drivers and Constraints Tool during the discussion. At the
end of the discussion, collect each student’s completed Tool.
Student Pages
See below.
31
Name:
Date:
Exploring With A Groundwater Model
1. Draw The Model: Below is a fold-over diagram of the groundwater model. Fold the diagram to make a 90°
angle on the fold line. The top portion of the diagram represents the view looking down at the land. The bottom
portion represents the cross-section view that you see when you look at your model from the side. Draw and
label your fold-over diagram with as much information from your groundwater model as you can.
Fold line
32
2. Where Are the Bottoms of the Wells?
Observe as your teacher pours blue-tinted water into the model and then pumps first from Well A and then
from Well B. Based on your observation, decide where you think the bottom of each well is and why.
Draw how deep you think the well tubes are for Well A and Well B in your drawing of the model on page 1.
Explain your reasoning for your ideas about how deep the wells are.
In the real world, what factors besides pumping from a well do you think could impact the level of water in the
ground?
How do you think the level of the groundwater would change in the spring? In the summer? Why?
33
3. Explore With A Model
Your teacher will give each group a groundwater model to work with. Explore with your model by gently
pumping and/or adding water as you’d like. As you explore, write down your ideas about the questions below.
Does the water seem to flow differently through different materials? Explain any patterns you see.
In the real world, what do you think determines which direction groundwater will move underground?
Write down all the ideas you can come up with about what causes water to move the way it does in the model
and underground.
4. Wrap Up
When you are done exploring with your model and responding to the questions above, please do the following:
a. Pump water out of your model until the level of the water is below the bottom of the lake.
Once you have done this, your teacher will collect your model.
b. Carefully empty the storage tank into the sink.
c. Clean up your workstation.
34
Activity 3: Application Assessment: Where Would You Drill A Well?
Summary of Activity
Given a map/cross-section, students are asked to suggest a location for a new well and justify their answer
based on the features on the map and cross-section.
Materials


Document camera
One Where Would you Drill a Well Handout for each students
Activity Procedures
1. Note: You may choose to send this assessment home as homework to collect, then conduct the
class discussion after you have reviewed students’ sheets.
Question: Establish a Question
2. Show students the handout and model how to use the diagram. Make sure students understand
the task. The river in particular may be confusing to students. The river is at a lower elevation than
the road and house. Thus, river on top looks disconnected from the river in the cross-section
portion of the diagram.
Apply: Apply knowledge to new context
3. Handout the assessment sheet to each student. Students will work alone on this task
Practices
as a homework assignment (or, if time is available, provide time in class for students
Analyze &
to work on this assessment in pairs).
Interpret
Data
4. (Next day) Collect and review students’ responses next day.
5. Return handouts to students and have them present their choices and reasons to
the class. If possible, use a document camera so students can show their drawings as
they present their ideas. Ask individuals in the class if they agree or disagree with
Practices
the presenting student’s choice and to provide their reasons (use thumbs
Construct
up/thumbs down strategy). Without giving the students the “correct” answer, guide
Arguments
the discussion to help the students come to consensus. The best location for a well
from
in this cross section is near the river, below the first confining layer. Here, the
Evidence
aquifer will be recharged by the river. A student could put the well above the first
Communicate
confining layer, but there is less surface area to recharge the aquifer, this aquifer is
Arguments
fairly shallow, and the recharge area is partially covered with a road (Cherry Lane).
However, in this activity, it is just as important that students provide reasonable
Evaluate
evidence and reasons for their well positions as that they locate the well in the
Arguments
“right” place.
Student Pages
See below.
35
Reasoning Tools for Understanding Water Systems
Name:
Date:
Where Would You Drill A Well?
You own all of the land in the picture on the back of this sheet. You need to drill a well for water for your
house. You do not want to take the water directly from the river because the river water is not a clean
as the groundwater.
1. Examine the cross-section diagram below and DECIDE and DRAW IN where you would like to drill
your well and how deep you will drill it.
Keep in mind: It costs about $9 per foot to drill a well, so you don’t want to have to spend too much
money. But you also want to make sure you have enough water for your how.
2. Explain why you chose to put the well WHERE and HOW DEEP you did.
36
Reasoning Tools for Understanding Water Systems
37
Reasoning Tools for Understanding Water Systems
Activity 4: Get the Groundwater Picture
Activity Summary
Students use well data to construct a cross-section and then use the cross-section to analyze
the groundwater system.
Project Wet: Pages 136-143
Prior Activities
Prior to doing this activity, students should be familiar with cross-sections and permeability.
Activities 1-3 in this sequence would provide these experiences.
Tools for Reasoning
Tracing Pathways
Part III, Step 5c, page 140: What are water sources for the unconfined aquifer?
1. Label several spots on the cross-section. Have students use the Pathways
Tool to trace back to possible sources of water. Encourage them to
Practices
think about multiple pathways that the water might take.
 Using Models
 Analyzing
and
Interpreting
Data
Before
After
Before
#5 in Wetland
at surface
#6 in fine
sand 1” (50
feet) down
After
Before
#7 in medium
sand, 2” (100)
down
#8 in fine
sand at
surface
farmland
#8 in fine
sand 1” (50
feet) down
# 8 in fine
sand 2” (100
feet) down
After
Where is the
water?
#8
in medium sand 3”
(150 feet) down
#8 in medium
sand 4” (200
feet) down
#9 in medium
sand 4” (200
feet) down
#8 in
sandstone 6”
(300 feet)
down
#8 in medium
sand 5 “ (250
feet) down
#10 in
medium sand
5” (250 feet
down)
#11 in
medium sand
6” (300 feet)
down
Gravity pulls the water downward. The water table is lower toward well #16, so the water will
likely flow towards this low point in the water table. Once the water reaches the clay layer, which
is impermeable, the water will not go any deeper and will flow only towards the cone of
depression at well #16.
38
Reasoning Tools for Understanding Water Systems
Drivers and Constraints Tools
1. Part III, Step 4, page 139: Students are asked to trace a drop of water through their well log
and identify where the water would move fastest, where it would move slowest, and where
it would be restricted. Before students can answer this question, they first have to trace the
water through their column. Use the Drivers and Constraints Tool to support students in
considering the effects of permeability in each layer.
Where does the
water start?
Farmland at # 8
What are the drivers?
Gravity pulls water
down
What are the constraints?
Permeability –
Fine sand – permeable
Medium sand – more permeable
Sandstone – permeable but not as
permeable as fine sand
Clay – Impermeable
Where does the water go?
The water will flow
down and stop at
the clay layer
Process - Infiltration
The water will infiltrate at the top of the ground (farmland). Gravity will pull the
water down. The water will flow fastest through the medium sand layer because it
has the highest permeability. It will flow slowest through the sandstone layer and
then stop flowing down at the impermeable clay layer.
39
Reasoning Tools for Understanding Water Systems
2. Part III, Step 5b, page 140. Ask students what direction the groundwater is moving in the
unconfined aquifer. The biggest hint is the decrease in elevation of the impermeable layer,
which would allow water in the unconfined aquifer to move down in elevation, similar to
how surface water moves downhill. The cone of depression shows that well pumping has
altered this general trend in the area to the right of the well (columns 16-21). Use the
Drivers and Constraints Tool to support students in considering the drivers that would pull
water downward and the constraints (impermeable layer) that would define the pathway.
Where does the
water start?
Column #3
What are the drivers?
Gravity pulls water
down
What are the constraints?
Permeability –
Fine sand – permeable
Medium sand – more permeable
Sandstone – permeable but not as
permeable as fine sand
Clay – Impermeable
Where does the water go?
The water will flow
towards column 16
Process - Infiltration
The water will infiltrate at the top of the ground (farmland). Gravity will pull the
water down through the sand layer. The coarse sand has the highest permeability.
The sandstone has a low permeability and the clay is impermeable. The water will
not infiltrate below the clay layer. The sandstone layer dips to the right and the
water table dips to the right forming a cone of depression. There may be a well at
column 16 that is pulling water out. The water in column 3 will flow along the
sandstone and clay layers towards column 16 where it may be pulled out in a well.
40