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● ! this is interesting
● * this is important information to answer the teaching task
How much water is there on, in, and above the Earth? USGS
The World's Water "Water, Water, Everywhere...."
This text was adapted from Where is Earth's water? USGS Water-Science School
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"Water, Water, Everywhere...." You've heard the phrase, and for water, it really is true. Earth's
water is (almost) everywhere: above the Earth in the air and clouds, on the surface of the Earth
in rivers, oceans, ice, plants, in living organisms, and inside the Earth in the top few miles of the
ground.
Below are two representations of where Earth's water resides. The left-side bar chart shows
how almost all of Earth's water is saline and is found in the oceans. Of the small amount that is
actually freshwater, only a relatively small portion is available to sustain human, plant, and
animal life.
Figure 1: Where is Earth’s
Water?
● In the first bar, notice how only
2.5% of Earth's water is
freshwater - the amount needed
for life to survive.
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The middle bar shows the
breakdown of freshwater. Almost
all of it is locked up in ice and in
the ground. Only a little more
than 1.2% of all freshwater is
surface water, which serves
most of life's needs.
The right bar shows the
breakdown of surface freshwater.
Most of this water is locked up in
ice, and another 20.9% is found
in lakes. Rivers make up 0.49%
of surface freshwater. Although
rivers account for only a small
amount of freshwater, this is
where humans get a large portion
of their water from.
"Where is Earth's water? USGS Water-Science School." 2014. 1 Sep. 2015
<http://water.usgs.gov/edu/earthwherewater.html>
The globe image represents how much actual water exists, compared to the total size of the
Earth. Notice the blue spheres (representing water). They look small because they are being
compared to the size of the whole globe. The image shows that Earth's water resides in a very
thin slice all around the Earth's surface.
● Look at the globe below. Notice the tiny bubble hovering over Georgia, USA. This ball of water
represents all of the freshwater in lakes and rivers. The water in that bubble has the huge
responsibility of meeting most of the needs of humans and animals.
Figure 2: How much water is there on, in and above the Earth?
All Earth's water, liquid fresh water, and water in lakes and rivers
Spheres showing:
(1) All water (sphere over western U.S., 860 miles in diameter)
(2) Fresh liquid water in the ground, lakes, swamps, and rivers (sphere over Kentucky, 169.5 miles in diameter), and
(3) Fresh-water lakes and rivers (sphere over Georgia, 34.9 miles in diameter).
Credit: Howard Perlman, USGS; globe illustration by Jack Cook, Woods Hole Oceanographic Institution (©); Adam Nieman.
View full size
The Earth is a watery place. But just how much water exists on, in, and above our planet? About 71
percent of the Earth's surface is water-covered, and the oceans hold about 96.5 percent of all Earth's
water. Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, in the
ground as soil moisture and in aquifers, and even in you and your dog.
Water is never sitting still. Thanks to the water cycle, our planet's water supply is constantly moving from
one place to another and from one form to another. Things would get pretty stale without the water cycle!
All Earth's water in a bubble
This drawing shows blue spheres representing relative amounts of Earth's water in comparison to the size
of the Earth. Are you surprised that these water spheres look so small? They are only small in relation to
the size of the Earth. This image attempts to show three dimensions, so each sphere represents
"volume." The volume of the largest sphere, representing all water on, in, and above the Earth, would be
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about 332,500,000 cubic miles (mi ) (1,386,000,000 cubic kilometers (km )), and be about 860 miles
(about 1,385 kilometers) in diameter.
The smaller sphere over Kentucky represents Earth's liquid fresh water in groundwater, swamp water,
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rivers, and lakes. The volume of this sphere would be about 2,551,000 mi (10,633,450 km ) and form a
sphere about 169.5 miles (272.8 kilometers) in diameter. Yes, all of this water is freshwater, which we all
need every day, but much of it is deep in the ground, unavailable to humans.
Do you notice the "tiny" bubble over Atlanta, Georgia? That one represents fresh water in all the lakes
and rivers on the planet. Most of the water people and life on earth need every day comes from these
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surface-water sources. The volume of this sphere is about 22,339 mi (93,113 km ). The diameter of this
sphere is about 34.9 miles (56.2 kilometers). Yes, Lake Michigan looks way bigger than this sphere, but
you have to try to imagine a bubble almost 35 miles high—whereas the average depth of Lake Michigan
is less than 300 feet (91 meters).
Water is on and in the Earth
The vast majority of water on the Earth's surface, over 96
percent, is saline water in the oceans. The freshwater
resources, such as water falling from the skies and
moving into streams, rivers, lakes, and groundwater,
provide people with the water they need every day to live.
Water sitting on the surface of the Earth is easy to
visualize, and your view of the water cycle might be that
rainfall fills up the rivers and lakes. But, the unseen water
below our feet is critically important to life, also. How do
you account for the flow in rivers after weeks without
rain? In fact, how do you account for the water flowing
down a driveway on a day when it didn't rain? The
answer is that there is more to our water supply than just
surface water, there is also plenty of water beneath our feet.
Even though you may only notice water on the Earth's surface, there is much more freshwater stored in
the ground than there is in liquid form on the surface. In fact, some of the water you see flowing in rivers
comes from seepage of groundwater into river beds. Water from precipitation continually seeps into the
ground to recharge aquifers, while at the same time water in the ground continually recharges rivers
through seepage.
Humans are happy this happens because we make use of both kinds of water. In the United States in
2005, we used about 328 billion gallons of surface water per day,and about 82.6 billion gallons of
groundwater per day. Although surface water is used more to supply drinking water and to irrigate crops,
groundwater is vital in that it not only helps to keep rivers and lakes full, it also provides water for people
in places where visible water is scarce, such as in desert towns of the western United States. Without
groundwater, people would be sand-surfing in Palm Springs, California instead of playing golf.