Unit 3 – The Water Cycle How Do Californians Get the Water They Need?
Jan 01, 2016
California Science Standard3.e Students know the origin of the water
used by their local communities.
Shasta Dam, California
Where does the water in the Sacramento River come from?
Is the water in the river fresh water or salt water?
Why would a community consider building a dam?
VocabularyWatershed – The area of land in which water
runs off into a particular system of creeks and rivers.
Water ResourcesFreshwater is vital to human health.It is also necessary for growing many kinds of
plants that people rely on for food.
Water ResourcesFresh water is vital to human health.It is also necessary for growing many kinds of
plants that people rely on for food.
What are some other ways that people use freshwater resources?
What are some ways that people use saltwater resources?
Local Water SourcesMost communities in California get their fresh
water from lakes and rivers.These communities’ water supply depends on how
much rain and snow falls during the year.When rain or snow falls it collects in a watershed.
As snow melts from the top of a mountain, it flows down in small creeks.
The creeks join to form rivers.The rivers join to form larger rivers.
This system of creeks and rivers “drains” the watershed.
Local Water SourcesA community may be able to take its water
directly from the rivers of a watershed.The amount of water in a river changes from
season to season.During spring, rivers may have plenty of water
from melted snow.Dry seasons, the water level may be very low.
There may not be enough water to meet the community needs.
Local Water SourcesMany communities build dams to store water
for dry seasons.In California, dams are often used to hold
water.Water collects behind a dam to form a
reservoir. This water is being stored for future use.
Local Water SourcesIf a community uses more water than is
available from its watershed, it may need to bring in water from another watershed.The community would use an aqueduct, a pipe
or channel, to transport water.
Local Water SourcesLos Angeles uses two large aqueducts.
The first aqueduct was built in the early 1900’s. As the city grew, so did it’s need for water. The
second aqueduct was build in 1970.
How has Los Angeles provided its citizens with water?
GroundwaterNot all of California’s water supply is surface
water.About 40% of California’s population uses
groundwater.Groundwater is water under Earth’s surface
located in the spaces between rocks and soil.Not all the rain that falls on land runs off into
creeks and rivers. Some soaks in the soil and inside rocks.
GroundwaterAs water moves through these spaces, some
of it sticks to soil particles, but most of the water continues moving downward.It soon reaches an area that is filled with
water. This is called a water table.
GroundwaterYou can think of a water table as a line under
the ground.The ground above the line has air gaps in it.The ground below the line is totally filled with
water.The water table rises during wet season, and
drops during dry seasons.
GroundwaterGroundwater is can be found in rocks that have
pores, or small openings.The pores and spaces allow water to pass between
them.A rock layer can store a lot of water and let it flow
through. This is called an aquifer. Water can be obtained from them by drilling
wells.
GroundwaterA well is drilled from the surface to a spot
below the water table.A pump is used to bring the water to the
surface.A well can supply a house, neighborhood, or
even a city.If too much water is removed from a well, the
water table will drop. This will cause the well to become dry.
People should not use more well water than is replaced naturally by rainfall. Why?