1. Water on Earth
Notes

2. How much water? About 70-71% of the Earth is covered in water.
Almost 97% of the Earth’s water is saltwater.
Approximately 3% of the Earth’s water is freshwater.
Humans and many living things can only survive in/on freshwater.

3. Where is water found on Earth?
Water is found in oceans, lakes, rivers, streams and in rock layers underground called aquifers.
A large amount of water is also found in living things.

4. Available fresh water for drinking is less than 1%!
Water on Earth
97% of Earth’s water is saltwater and 3% is freshwater.
Available fresh water for drinking is less than 1%!

5. Fresh Water
Approximately 76% of Earth’s freshwater is frozen. This means humans and other organisms cannot use it for survival.
Icebergs and glaciers = frozen freshwater.
Icebergs break off from massive (large) glaciers at the north and south poles.

6. How have people used water?
The first human settlements were established near springs, rivers, and lakes.
In order for civilizations to grow and flourish (succeed), they needed reliable fresh water sources for :
Drinking water: for themselves and their livestock.
Irrigation: the process of supplying water to areas of land to make them suitable for growing crops (bringing water to fields to grow plants for food).

7. As cities grew, different ways were invented to collect water.
Tunnels: underground pathways for water.
Aqueducts: artificial above ground water pathways.
Wells: natural pockets of groundwater in aquifers.
Pumps: used for bringing water up from underground.
Cisterns: artificial tanks for storing water.
Reservoirs: artificial or natural lakes where water is stored.

8. Aqueducts
Cisterns
Reservoirs
Well

9. Main Uses for Water in the United States
Agriculture (farming): water that is used for irrigation (bringing water to crops).
Industry: water is used to make products. It is also used to run and cool machines in factories.
Transportation: rivers and oceans serve as natural highways to move people and goods from one place to another.
Recreation: swimming, boating, fishing and skiing.

10. Hydroelectric Power
Water is also used for hydroelectric power generation (making electricity using water).
Water is stored in a reservoir behind a dam (has potential energy).
When allowed to flow through floodgates, it has kinetic energy and turns the blades of a turbine producing mechanical energy.
The shaft of the turbine is connected to a generator that has a large magnet surrounded by coils of wire. The shaft turns the magnet and produces electricity.
Electricity is sent to homes through cables.

11. STORED water behind the dam has POTENTIAL energy
FLOWING water released when floodgates open has KINETIC energy
Cables transport electricity to homes and businesses
reservoir
dam
floodgate
generator
turbine