In this hands-on activity, participants will model how much of Earth’s surface is covered by water, and then will see how much of that water is actually freshwater that is accessible to us for our needs. This activity will be done by pairs of participants (each pair will need a plastic cup, a smaller medicine cup, an eye-dropper, and a water source). I will use a PowerPoint presentation to introduce the directions and provide additional information on each aspect of the model that we make. We will also see a GPM video clip entitled, “The Freshwater Connection” (1:24 )
Engage: Ask students what they observe. Help them to identify water in all three forms- as a liquid in the oceans, as a gas in the clouds, and as a solid in the North Pole ice packs.
Use this slide to reinforce the fact that water exists in three forms- and help them to discover that it is the temperature that causes water to change from one form to the other.
Each small group (about 4-6) of students will need a clear plastic cup, access to water, a smaller medicine cup or petri dish, and an eye-dropper.
In the pie charts above, the top pie chart shows that over 99 percent of all water (oceans, seas, ice, most saline water, and atmospheric water) is not available for our uses. And even of the remaining fraction of one percent (the small brown slice in the top pie chart), much of that is out of reach. Considering that most of the water we use in everyday life comes from rivers (the small dark blue slice in the bottom pie chart), you'll see we generally only make use of a tiny portion of the available water supplies. The bottom pie shows that the vast majority of the fresh water available for our uses is stored in the ground (the large grey slice in the second pie chart). http://ga.water.usgs.gov/edu/earthwherewater.html
Where is Earth's water located and in what forms does it exist? You can see how water is distributed by viewing these bar charts. The left-side bar shows where the water on Earth exists; about 97 percent of all water is in the oceans. The middle bar shows the distribution of that three percent of all Earth's water that is freshwater. The majority, about 69 percent, is locked up in glaciers and icecaps, mainly in Greenland and Antarctica. You might be surprised that of the remaining freshwater, almost all of it is below your feet, as groundwater. No matter where on Earth you are standing, chances are that, at some depth, the ground below you is saturated with water. Of all the freshwater on Earth, only about 0.3 percent is contained in rivers and lakes—yet rivers and lakes are where most of the water we use in our everyday lives exists.
Discuss difference between fresh and salt water- emphasize need for freshwater to meet our needs, explain why we can’t use salt water for our needs
Freshwater is not evenly distributed over the planet.
You can skip these slides unless you have time and want to discuss the ways we use freshwater in our daily lives.
See note for previous slide
Graphic display of data presented- amount of freshwater we use in US for various purposes.
Freshwater: A Precious Resource
June 26th, 2013
: Hav Begun?
ue G e Wars
Freshwater vs. Saltwater
How much of Earth’s water is freshwater?
We will make a model of Earth’s freshwater.
1.Take the plastic cup, and imagine that the cup is a
model of Earth’s surface.
2.Fill up ~ 75% with water. This represents how much
of Earth’s surface is covered with water.
3.Take out one eye-dropper of water, and place it in
the small medicine cup. This represents how much of
Earth’s water is freshwater- ~ 2.5%
4.Take one drop of this water- this represents how
much freshwater is easily accessible to us!
Freshwater is a precious resource.
How do we use freshwater?
In addition to home use, fresh water is used for
transportation, agriculture, heating and cooling,
industry, livestock, and many other purposes. That one
percent of water is primarily used in eight different
ways, or categories:
• Domestic. Residential home indoor and outdoor use,
such as drinking, cleaning, and watering lawns
• Public supply. Public and commercial buildings, such
as schools and restaurants
• Irrigation. Watering systems for farms that grow food
• Livestock. Watering systems for animals on ranches
• Aquaculture- Watering systems for fish farms and
• Industrial -Water used for manufacturing products,
including food, paper, and petroleum products
• Mining- Water used for extracting natural resources
such as metals, minerals, natural gas, and oil
• Thermoelectric- Water used for generating electricity
using steam-driven generators
Estimated Water Use in US
Public Supply 11%
Other- 8%: Mining 1%, Industrial 4%, Aquaculture 2%, Livestock 1%
From the American Water Works Assoc.
Keeping track of freshwater
• Rain gauges- not evenly distributed, none over
oceans, measures at local level which varies widely
• Weather radar- ground-based, not evenly
distributed, not over oceans, measures at local level
• Satellites: operational and research, global level
NOAA, NWS- operational: predicting, forecasting
Impact of climate change on freshwater availability
Impact of global rainfall on natural disasters:
drought, tropical cyclones, landslides, etc…
World health concerns: water-borne disease, water