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)
5.
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
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.