Lesson 3 surface water and groundwater

Unit 1 Lesson 3 Surface Water and Groundwater
Copyright © Houghton Mifflin Harcourt Publishing Company

Getting Your Feet Wet
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.

• 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.

• 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.

• How does fresh water move through this
environment?

Cry Me a River
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.

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.

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.

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.

surface?
• Identify the tributary, river, divide, load, and
watershed in the environment below.

In Deep Water
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.

• 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.

• 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.

• Gauge the extent of porosity and permeability
(high or low) in each image.

• 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.

• Label the discharge and recharge zones of the
aquifer.

Making a Splash
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.

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.

Troubled Waters
• 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.

Lesson 3 surface water and groundwater

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