The water cycle recycles the Earth's water supply, with water evaporating from oceans, lakes and vegetation before condensing into clouds and falling as precipitation. Most of the Earth's water is saltwater, while just over 1% is fresh surface and groundwater. Groundwater is stored in aquifers underground, where it is recharged through infiltration and flows through porous rock, being pumped up by wells. However, overuse and pollution threaten this important freshwater resource.

1. Chapter 11, Section 1: Water Resources
Standards: SEV5e

2. The Water Cycle
 The same amount of
water had been on the
planet for billions of
years.
 The water you drink
today is the same water
dinosaurs drank!
 Water is a renewable
resource that is recycled
through the water cycle.

3. The Water Cycle
 Evaporation
 Water evaporates when heated by
sun (leaves salts behind)
 Transpiration- water evaporation
from plants
 Condensation
 As water vapor rises it cools,
condenses, and collects on dust
particles in the sky (condensation
nuclei) and forms clouds.
 Precipitation
 When clouds get too full of water
they drop it as precipitation
 Infiltration and Runoff
 Water either
 Infiltrates the soil- pass slowly through
soil to recharge an aquifer
 Runs off into a nearby lake or stream.

4. How much water is on Earth?
 97% is saltwater in
oceans & saltwater lakes.
 3% is freshwater
 2% frozen in ice caps &
glaciers (unusable)
 1% groundwater &
surface water (usable)

6. How is our usable water distributed?
 Surface water
 Groundwater

7. What is surface water?
 Fresh water above
ground.
 Important for
 Drinking water
 Transportation of goods
via ships
 Irrigation
 Aquaculture
 Power for industry

8. What are the types of Surface Water?
 Rivers & streams
 Fast moving
 Cold, highly oxygenated
 Insect larvae, trout, long narrow
plants, algae
 Lakes & ponds
 Slow moving
 Warm, less oxygenated
 Bass, catfish, cattails, leeches
 Wetlands
 Covered with water most of the
year
 Absorb and slow water flow
 Filter pollutants & sediment
 Provide breeding ground for
water birds, shellfish, fish

9. What is a river system?
 Streams form in higher
elevations from rainfall or
melting snow.
 As they move downhill they
combine with other streams
to form rivers.
 Streams that feed rivers are
called tributaries.
 This interconnection of
streams to form rivers is the
river system
 Ex: McEachern creek flows
to Noses Creek to Sweetwater
Creek to Chattahoochee
River

10. Lake Lanier
West Point
Lake
Walter F.
George
Lake
Lake
Seminole
Apalachicola
River
Flint River
Chattahoochee
River

11. What is a watershed?
 Area of land that drains
into a stream/river.
 Pollution anywhere in
the watershed could end
up in that river.
 We live in the
Chattahoochee River
watershed

12. What is groundwater
 Fresh water stored
underground in aquifers
 Most fresh water
resources are stored here
 Aquifer- area
underground with rocks
& gravel that have spaces
where water can
accumulate.

13. What is the water table?
 Top layer of water in
aquifer where soil is
saturated.
 In wet regions the water
table may reach surface
and create a natural spring.
 If aquifer is confined by
layer of rock may be under
pressure and squirt out of
ground as artesian well
 In desert regions water
table is usually very deep.

14. Ogallala Aquifer
 One of the largest in the world.
 Supplies 1/3 of groundwater used in
the U.S.
 Used mostly for irrigating crops.
 Now being used at increasing rate
(faster than can be recharged)
 Water table has dropped 100 ft in
some places of Ogallala.
 Wetlands rely on water table of
Ogallala where it comes to surface.
 If water table decreases, wetlands
dry out, water birds (sandhill
cranes) lose feeding & breeding
site.
 Farmers are trying to limit their use
by switching to crops that require
less water (wheat & sorghum)

15. What factors affect aquifer
recharge rate?
 Porosity
 Percentage of total volume of a
rock that has spaces
 Water is stored in these pore
spaces
 More porous the rock, the more
water it can hold.
 Permeability
 Ability of rock or soil to allow
water to flow through it.
 Sand- high permeability- lets
water flow through quickly.
 Clay- low permeability- holds
water so it flows slowly.
 Limestone, sandstone are
permeable materials that often
form aquifers.

16. How does an aquifer recharge?
 When it rains, water
percolates through region
of soil called recharge
zone.
 Recharge zone is
determined by what is on
surface of soil above
 Buildings, parking lots
reduce recharge zone
 Pollution can contaminate
recharge zone &
contaminate aquifer.
 Can take 10’s of 1,000’s of
years to recharge

17. How do wells impact groundwater
sources?
 Well- hole dug/drilled to
reach groundwater
 Well water is filtered by soil
before it reaches aquifer-
relatively clean. (usually
filters are added on the pump
that draws the water up)
 Must reach way below the
water table b/c water table
changes seasonally.
 If water is pumped out
quickly it will create a cone of
depression that may prevent
other wells from reaching
water.

18. You should be able to…
 Describe the distribution of water on Earth. Where is
most of the freshwater located?
 Explain why fresh water is considered a limited
resource.
 Explain why pollution in a watershed poses a potential
threat to the river system that flows through it.
 Describe how water travels through rocks and soil.