7th grade science, Friendswood, Texas

1. Water!
Surface Water, Ground Water,
and Treatment Systems
TEKS 7.8C
The effects of human activity
on groundwater and surface water
in a watershed.

2. The History of Water
• Water is continually moving around, through, and above the
Earth as water vapor, liquid water, and ice.
• Water is continually changing its form.
• The Earth is pretty much a "closed system," like a terrarium.
That means that the Earth, as a whole, neither gains nor loses
much matter, including water.
• Although some matter, such as meteors from outer space, are
captured by Earth, very little of Earth's substances escape into
outer space. This is certainly true about water. This means that
the same water that existed on Earth millions of years ago is
still here.
• Thanks to the water cycle, the same water is continually being
recycled all around the globe. It is entirely possible that the
water you drank for lunch was once used by Mama Allosaurus
to give her baby a bath.

3. The Water Cycle
• Earth's water is always in
movement on, above, and below
the surface of the Earth.
• Since the water cycle is truly a
"cycle," there is no beginning or
end.
• Water can change states among
liquid, vapor, and ice at various
places in the water cycle, with
these processes happening in
the blink of an eye and over
millions of years.

5. Distribution of Earth’s Water

6. So That Means…
Of all the water on
Earth, humans
cannot use 99% of
it. Of the 1% we
can use, 99% is
ground water, and
1% is surface
water.

7. Surface Water
Clear Creek near
IH-45 and 518.
• Surface water is
any water that is
on the surface of
the Earth.
• This includes
rivers, streams,
creeks, lakes, and
reservoirs.

8. Watersheds
• A watershed is the area of
land where all of the water
that falls in it and drains off
of it goes into the same
place (in our case, Clear
Creek).
• The word watershed is
sometimes used
interchangeably with
drainage basin or
catchment.
• The watershed consists of
surface water -- lakes,
streams, reservoirs, and
wetlands--and all the
underlying ground water.
Clear Creek tributary near
Blackhawk Road.

9. Harris County Watersheds
Kemah
You are here!

10. Clear Creek Watershed
Drainage Area:
197 square miles
Watershed
Population
(Harris County):
118,026
Open Stream
Miles:
154 miles
Kemah
You are here!
Primary Streams:
Clear Creek
Turkey Creek
Mud Gully

11. All About the Clear Creek
Watershed
Clear Creek tidal
area. Near IH-45 and
FM 518.
• The Clear Creek watershed
is located in southern
Harris County.
• The watershed
encompasses portions of
Harris, Galveston, Brazoria
and Fort Bend counties; 16
cities including Houston,
Brookside Village,
Pearland, Friendswood,
League City, Pasadena,
and the Clear Lake Area
communities.

12. Environment of the Clear Creek
Watershed
• Clear Creek between Clear
Lake and the City of
Friendswood is in a natural
state.
• Its bottom elevations are
below sea level and subject
to tidal influences.
• A number of natural and
recreational parks have been
developed along the creek.
• Much of the channel
Clear Creek from Challenger
upstream of this line also
Seven Memorial Park
supports heavy vegetative
growth.

13. Flooding in the Clear Creek
Watershed
• Flooding occurs
frequently along
various reaches of the
main channel and its
tributaries.
• Storm surge has also
caused flooding within
the watershed and has
the potential to extend
upstream from Kemah
to I-45.

14. Land Use in the Clear Creek
Watershed
As development continues,
there is a great need for
systems that reduce flooding.
• Development activity has
historically been
concentrated in the lower
end of the watershed
around Clear Lake and
several smaller cities in the
mid and upper portions of
the watershed.
• However, in recent
decades, development
activity has increased
throughout the watershed
and is expected to
continue.

15. Flood Reduction Measures in
the Clear Creek Watershed
STRUCTURAL TOOLS
• Channel modification is a
man-made change to a
channel's characteristics,
typically for the purposes of
reducing flood damages by
increasing its overall
conveyance capacity.
• This can be accomplished by
widening and/or deepening
the channel, reducing the
friction by removing woody
vegetation, or by occasionally
adding concrete lining.

16. Flood Reduction Measures in
the Clear Creek Watershed
STRUCTURAL TOOLS
• A stormwater detention basin
is a large, usually excavated
area of land, frequently
adjacent to a channel, which
is designed to receive and
hold above-normal
stormwater volumes.
• The detained stormwater
then slowly drains over time
out of the detention basin as
water surface elevations in
the receiving channel
recede.

17. Flood Reduction Measures in
the Clear Creek Watershed
STRUCTURAL TOOLS
• Bypass channel
construction involves
building a new
channel that is
attached to an
existing channel and,
as mentioned,
conveying the excess
stormwater runoff
around its original
path.

18. Flood Reduction Measures in
the Clear Creek Watershed
NON-STRUCTURAL TOOLS
• Buyout and demolition of
structures that were built
deep in flood prone areas
where structural projects to
reduce flood levels are
impractical is a nonconstruction solution.
• Once a flood prone house
is bought and demolished,
it will never incur flood
damages again. The
District actively pursues
voluntary buyout
opportunities.

19. Uses of Surface Water
• The main uses of
surface water
include drinkingwater and other
public uses,
irrigation uses, and
for use by the
thermoelectric-power
industry to cool
electricity-generating
equipment.

20. Surface Water Withdrawals,
2000.

21. Total Fresh Surface Water
Withdrawals, 2000

22. 160,000
135,000
140,000
120,000
100,000
80,000
80,000
60,000
40,000
27,300
20,000
59
747
2,640
14,900
1,240
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Withdrawals in millions of gallons per day
Fresh Surface Water
Categories by Use, 2000
Categories of Surface Water Use

23. Ground Water
• Below a certain depth, the ground that is permeable
enough to hold water is saturated with water.
• The upper surface of this zone of saturation is called
the water table.
• The saturated zone beneath the water table is called
an aquifer, and aquifers are huge storehouses of
water.

24. Ground Water
• Groundwater is the part of precipitation that seeps down
through the soil until it reaches rock material that is
saturated with water.
• Water in the ground is stored in the spaces between rock
particles (no, there are no underground rivers or lakes).
• Groundwater slowly moves underground, generally at a
downward angle (because of gravity), and may eventually
seep into streams, lakes, and oceans.
Unsaturated soil
Saturated
soil

25. Aquifers
• Aquifers are underground
reservoirs.
• Almost no bacteria live in
aquifers. Many pollutants
are filtered out as the water
passes through the soil on
its way to the aquifer.
• To tap the groundwater in
an aquifer, wells are dug
until they reach the top
layer of the aquifer, the
water table.
• When a lot of water is
pumped from an aquifer, or
when there is a dry spell,
the water table sinks lower.

26. Aquifers
•
•
•
Wells can be drilled into the aquifers and water can be pumped out.
Precipitation eventually adds water (recharge) into the porous rock of
the aquifer.
The rate of recharge is not the same for all aquifers, though, and that
must be considered when pumping water from a well. Pumping too
much water too fast draws down the water in the aquifer and eventually
causes a well to yield less and less water and even run dry.

27. Water Treatment
Alum and other
chemicals are
added to water to
attract dirt
particles.
A small amount
of chlorine is
added or some
other disinfection
method is used
to kill any
bacteria or
microorganisims
that may be in
the water.
Coagulated particles
sink to the bottom.
Clear water moves
on to filtration.
The water passes
through filters, some
made of layers of sand,
gravel, and charcoal that
help remove even
smaller particles.
Water is placed in a
closed tank or
reservoir in order for
disinfection to take
place. The water then
flows through pipes to
homes and businesses
in the community.

29. Bibliography
•
•
•
•
http://ga.water.usgs.gov/edu/mearth.html
http://www.gma.org/katahdin/aquifer.html
http://www.hcfcd.org/photogallery.html#
http://water.epa.gov/learn/kids/drinkingwater/