This document discusses where fresh water is found on Earth, how it moves through surface water and groundwater systems, and how humans use fresh water resources. Only 3% of Earth's water is fresh, with 1% as liquid water found on the surface in streams, rivers and lakes (surface water), and below the surface in aquifers (groundwater). Surface water flows downhill and joins together in river systems within watersheds, eventually discharging into the ground to recharge aquifers, or into the ocean. Groundwater flows through aquifers, being recharged in upland areas and discharging in lowlands. Humans rely on both surface and groundwater for agricultural, industrial, and domestic uses.

1. Unit 1 Lesson 3 Surface Water and Groundwater
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2. Getting Your Feet Wet
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Where on Earth is fresh water found?
• Only 3% of Earth’s water is fresh water, and most
of that is frozen as ice and snow. So only about
1% of Earth’s water is fresh liquid water.
• This fresh liquid water is found both on and below
Earth’s surface.
• This tiny percentage of Earth’s water must meet
the large demand that all living things have for
fresh, clean water.
Unit 1 Lesson 3 Surface Water and Groundwater

3. Where on Earth is fresh water found?
• Water that collects on Earth’s surface is called
surface water. It is found in streams, rivers, and
lakes.
• It may begin as precipitation in the form of rain,
snow, sleet, or hail. On Earth’s surface, it flows
from higher ground to lower ground.
• The water that flows across Earth’s surface is
called runoff. Eventually, runoff can enter bodies
of water.
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Unit 1 Lesson 3 Surface Water and Groundwater

4. Where on Earth is fresh water found?
• Some rainwater and water from streams seeps
down into the ground, collecting in spaces
between rock particles.
• Water found in the spaces between rock particles
below Earth’s surface is called groundwater.
• The water table is the upper boundary of the
rock or sediment that is saturated with water.
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Unit 1 Lesson 3 Surface Water and Groundwater

5. Where on Earth is fresh water found?
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Unit 1 Lesson 3 Surface Water and Groundwater
• How does fresh water move through this
environment?

6. Cry Me a River
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How does water move on Earth’s
surface?
• Water trickling down a hillside may flow together
to form a stream, eroding soil and rock to make a
channel.
• A channel is the path that a stream follows. Over
time, the channel gets wider and deeper, as the
stream erodes rock and soil.
• Streams typically flow along weaknesses in
bedrock.
Unit 1 Lesson 3 Surface Water and Groundwater

7. How does water move on Earth’s
surface?
• A tributary is a smaller stream that feeds into a
river and eventually into a river system.
• A river system is a network of streams and rivers
that drains an area of its runoff.
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Unit 1 Lesson 3 Surface Water and Groundwater

8. How does water move on Earth’s
surface?
• A watershed is the area of land drained by a
river system.
• Streams, rivers, flood plains, lakes, ponds,
wetlands, and groundwater all contribute water to
a watershed.
• Watersheds are separated from one another by a
ridge or an area of higher ground called a divide.
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Unit 1 Lesson 3 Surface Water and Groundwater

9. How does water move on Earth’s
surface?
• Gradient is a measure of the change in elevation
over a certain distance. In other words, it is a
measure of the slope of the land.
• A river’s flow is the amount of water that moves
through the river channel in a given amount of
time.
• Materials carried by a stream are called stream
load. Rivers eventually deposit their stream loads
downstream.
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Unit 1 Lesson 3 Surface Water and Groundwater

10. How does water move on Earth’s
surface?
• Identify the tributary, river, divide, load, and
watershed in the environment below.
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Unit 1 Lesson 3 Surface Water and Groundwater

11. In Deep Water
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How does groundwater flow?
• When water trickles down from the surface and
reaches a rock layer with no pores or cracks, the
water pools to form an aquifer.
• An aquifer is a rock layer that stores groundwater
and allows the flow of groundwater.
• The water table can rise or fall depending on the
amount of water in the aquifer.
Unit 1 Lesson 3 Surface Water and Groundwater

12. How does groundwater flow?
• An aquifer stores water in open spaces, or pores,
between particles of rock or soil.
• The storage space in an aquifer is measured by
porosity, which is the percentage of the rock that
is composed of pore space.
• The greater the pore space is, the higher the
porosity is.
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Unit 1 Lesson 3 Surface Water and Groundwater

13. How does groundwater flow?
• Permeability is a measure of how easily water can
flow through an aquifer.
• High permeability means that the pores in the
aquifer are connected to one another, so that
water can flow easily.
• A useful aquifer has both high porosity and high
permeability.
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Unit 1 Lesson 3 Surface Water and Groundwater

14. How does groundwater flow?
• Gauge the extent of porosity and permeability
(high or low) in each image.
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Unit 1 Lesson 3 Surface Water and Groundwater

15. How does groundwater flow?
• The process by which surface water trickles down
and enters an aquifer is called recharge. It occurs
in an area called the recharge zone.
• The process by which groundwater becomes
surface water is called discharge and happens in
discharge zones.
• Through discharge and recharge, the same water
circulates between surface water and
groundwater.
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Unit 1 Lesson 3 Surface Water and Groundwater

16. How does groundwater flow?
• Label the discharge and recharge zones of the
aquifer.
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Unit 1 Lesson 3 Surface Water and Groundwater

17. Making a Splash
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How do people use surface water and
groundwater?
• In a typical home, about 50% of all water used is
for washing clothes, bathing, washing dishes, and
flushing toilets.
• About 33% is used to water lawns and gardens.
The rest is used for drinking, cooking, and
washing hands.
• In the United States, about 40% of fresh water is
used for agricultural activities like growing crops
and raising livestock.
Unit 1 Lesson 3 Surface Water and Groundwater

18. How do people use surface water and
groundwater?
• About 45% of the fresh water used in the United
States is used for industry.
• Surface water in rivers, streams, and lakes is used
to transport products and people, and for various
recreational activities.
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Unit 1 Lesson 3 Surface Water and Groundwater

19. Unit 1 Lesson 3 Surface Water and Groundwater
Troubled Waters
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• The limited supply of fresh water must be
managed to meet the demands of a growing
population.
• Scientists estimate that about 1 billion people
around the world do not have an adequate supply
of clean, fresh water.
• Scientists are developing technologies to obtain
clean, fresh water to meet global needs.