How Much Water is Available? Video Lecture | Class 7 Oxford Science: Chapter Notes, Worksheets & Tests

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As humans, we're well
aware we need water to live. Fortunately for us, we live on
a water planet. But that doesn't mean we have an entire globe of H2O
to use as we please.
So just how does the usable water break down for us?
A giant 97 percent of Earth's water is in the ocean, so we can't
use that. Three percent is freshwater, but even in that small
sliver, about two percent is locked in glaciers, ice caps, and groundwater.
That leaves about one percent of the freshwater on
Earth that is accessible and usable by humans. Let's imagine
all of that accessible freshwater fits into this tiny pool. Now we'll get to
some small numbers when we look at global freshwater.
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There really is a small fraction of usable and accessible freshwater on this
water planet, so how do we use that tiny pool? In the
United States, about 49 percent is used in thermoelectric power production.
While agricultural irrigation makes up about 31
percent. Eleven percent goes to public use in our cities and towns.
Four percent goes into industry and manufacturing,
and one percent is domestic use. The water coming out of our faucets
largely comes from precipitation. Measuring how much or
how little precipitation falls can impact how we live our daily lives.
Elsewhere around the globe, in developing countries, agricultural irrigation
accounts for about 70 percent of freshwater use,
while industrial use is 20 percent, and 10 percent for public consumption.
In places where access to usable freshwater is greatly limited,
knowing when and where precipitation may fall is critical to livelihoods.
Precipitation replenishes these tiny reservoirs of
freshwater, and data from the Global Precipitation Measurement mission will help
farmers, ranchers, and policy makers in these regions plan for
periods of drought, flooding and other extreme weather.
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