Water Resources

1. Environmental Geology Chapter 11 - Water Resources

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2.

11-2

3. Introduction to Water Resources

A person can live 1 – 2 weeks w/out water
Human body is 70% water
Food plants / crops need water
Oxygen result of photosynthesis
Water used for manufacturing, producing
concrete, and electricity
Water use in homes, landscaping
Population growth increases demand for fresh
water
11-3

4. Origin of Earth’s Water

Large meteor impact on Earth ejected debris
and formed the Moon
Then melting occurred, volcanic activity
Volcanic gases plus comet impacts formed
atmosphere rich in water vapor
Planet cooled, water condensed and rain fell
forming oceans
Tectonic activity allowed land masses to rise
above sea level and oceans became deeper
11-4

5. Hydrologic Cycle

Continual and cyclic transfer of water
between oceans, fresh water bodies,
atmosphere and land
Driven by solar radiation which causes
evaporation
“The Water Cycle II” – MySTAR > Library
tab > Films on Demand
11-5

6. Hydrologic Cycle – Figure 11.1

11-6

7. pH – Process of Hydrogen

https://water.usgs.gov/edu/ph.html
pH scale is logarithmic;
each step up is 10 fold
Water flowing out of
abandoned mines about 2
pH
Pure water is 7 pH
Normal rainfall 5.6 pH
due to CO2 in atmosphere
Heavy metals more toxic
as acidity increase

8.

9. Salinity

Amount of electrically charged ions (salts)
dissolved in water
Fresh water:
Few dissolved ions
Produced by evaporation (salts left behind)
Salt water (marine) – highly saline; 35,000
mg/L
Brackish – varying levels of salinity, where
fresh water meets marine
11-9

10. Fresh Water in Limited Supply

2.8% of planet’s water is fresh
77.4% of fresh water is locked up in glacial
ice
22.1% is ground or subsurface water
0.5% surface water
Fresh water is not evenly distributed across
Earth
Supply varies seasonally and throughout
geologic time
11-10

11.

Figure 11.2
Page 330
Table 11.1
Page 330
11-11

12. Human Use of Freshwater

Large increase following Industrial
Revolution
Use for manufacturing, producing energy,
flushing toilets
Agricultural irrigation
Withdrawals have declined and remained
steady since 1980s due to more efficient
use
11-12

13.

14. Use of Fresh Water

Consumptive – water is lost or consumed
City or municipal
Electricity generation
Personal
Irrigation – water lost due to evaporation and
transpiration
Non-consumptive
Washing dishes – almost all water returned to a water
supply source
Off stream use – water withdrawn from one source and
returned to a different source
Consumptive and off stream can disrupt natural systems
11-14

15. Surface Water Resources

River and streams – collect precipitation and
transport it to ocean
Some infiltrates in to groundwater
Water table – depth where porous materials are
completely saturated
Romans used aqueduct system
California uses aqueducts to deliver water to
L.A.
Impact of water withdrawal versus where it is
discharged
11-15

16. Supply of Freshwater

Unsustainable use harming natural systems and
beginning to limit growth and development of
human populations around world
Five options when faced with water shortages:
1. Increase storage, build reservoirs
2. Transport water from other sources
3. Conservation programs
4. Nontraditional sources
5. Voluntarily limit growth
11-16

17. Lakes and Reservoirs

Natural lakes relatively rare
Reservoir created when rivers are
dammed to create an artificial lake
upstream; stockpile of large amount of
freshwater; dam assists flood control
Negative impacts: floods large area
upstream, no or less sediment transported
downstream, more evaporation
11-17

18. Groundwater Resources

Groundwater – water that resides with the
void or pore space of subsurface materials
Three factors determine if groundwater is
a viable source:
Quantity – depends on porosity
2. Ease of withdrawal – hydraulic conductivity
and permeability
3. Quality
1.
11-18

19. Groundwater

11-19

20. Types of Aquifers

Aquifer – water bearing rock or sediment layer
that readily transmits water; hydraulic
conductivity is high
Aquitard – low conductivity, clay rich sediment,
shales, unfractured crystalline rocks; “confining
layers”
Unconfined aquifer – highly conductive, open to
atmosphere and surface waters
Confined aquifer – overlain by aquitard, sealed
off from surface
11-20

21. Groundwater

11-21

22. Movement of Groundwater

Hydraulic head
Height of water
table or
potentiometric
surface – height
water will rise;
measure of
potential energy in
confined aquifer
Hydraulic gradient
Slope or steepness
of water table
11-22

23. Movement of Groundwater

11-23

24. Groundwater Recharge

Process by which aquifers are replenished
by infiltrating water that ends up at the
water table
11-24

25. More Groundwater Sources

Springs – groundwater discharges at the surface
Mineral – high salinity
Warm water/hot water
Water wells and drawdown cones
Modern wells – small hole drilled into subsurface,
well casing lowered into well and submersible
pump brings water up; most are 50 – 100 feet
deep
Cone of depression - caused by pumping action
of well in water table or potentiometric surface;
can reverse direction of water flow
11-25

26. Springs

11-26

27. Draw Down

11-27

28. Impacts of Groundwater Withdrawals

May resort to groundwater mining
(Tucson, AZ)
Dry wells
Land subsidence (Mexico City)
Increased well costs
Reduced spring and stream flow
Saltwater intrusion
11-28

29. Selecting a Water-Supply Source

Groundwater
River
Reservoir
11-29

30. Case Study 11.1 Page 346

Ogallala Aquifer of western U.S.
Groundwater mining allowed this area to be
major grain producer
Semi arid region receives <16 inches rain/year to
28 inches/year
Transpiration prohibits much infiltration
Groundwater levels reduced by 200 feet
11-30

31. Alternative Sources

Desalinization – removing salts or dissolved ions
from sea water
Sea water is 35,000 mg salt/L and must be 500
mg/L to be safe for humans
Distillation – salt water boiled and water vapor
captured
Reverse osmosis – semi-permeable membrane
traps salts and allows H20 molecules to pass
Problem with disposing of super saline waste water
Expensive, only used in areas with acute water
supply problems
11-31

32. Alternative Sources

Reclaimed/recycled
Municipal wastewater recycling – can be
treated to be safe to drink
Reclaimed water not safe for drinking can be
used for irrigation or industrial use – cost
savings over using drinking water
Mixing treated waste water with normal water
to go through natural processes then filtration
and treatment resulting in drinking water
11-32

33. Alternative Sources

Industrial and domestic recycling
Non contact cooling water – reusing
water used as a coolant as temperature
changes does not contaminate it
“Graywater” – home waste water that
has not been used in a toilet can be
collected and reused
11-33

34. Alternative Sources

Aquifer storage and recovery – storing
excess surface water in an aquifer
Rain water harvesting
Underground or above ground cistern
11-34

35. Conservation

Use water more efficiently, more sustainably
2 basic categories - engineering practices and behavioral
practices
Domestic and commercial users – largest use of water for
irrigating lawns and landscaping
Xeriscaping – use native plants adapted to local climate
Efficient appliances
Municipal supply systems
Education, repair leaks, fees based on usage
Agriculture – better practices
No till farming
Contour plowing
More efficient irrigation
11-35

36. 20 Ways to Conserve Water in Your Home

1. Shower Bucket. Instead of letting the water pour down the
drain, stick a bucket under the faucet while you wait for your
shower water to heat up. You can use the water for flushing the
toilet or watering your plants.
2. Turn off the tap while brushing your teeth. Water comes out
of the average faucet at 2.5 gallons per minute. Don’t let all that
water go down the drain while you brush! Turn off the faucet after
you wet your brush, and leave it off until it’s time to rinse.
3. Turn off the tap while washing your hands. Do you need the
water to run while you’re scrubbing your hands? Save a few gallons
of water and turn the faucet off after you wet your hands until you
need to rinse.
4. If it’s yellow, let it mellow. This tip might not be for
everyone, but the toilet is one of the most water-intensive fixtures
in the house. Do you need to flush every time?
11-36

37.

5. Fix your leaks. Whether you go DIY or hire a plumber, fixing
leaky faucets can mean big water savings.
Re-use your pasta cooking liquid. Instead of dumping that water
down the drain, try draining your pasta water into a large pot.
Once it cools, you can use it to water your plants. Just make
sure you wait, because if you dump that boiling water on your
plants, you might harm them.
7. Head to the car wash. If you feel compelled to wash your
car, take it to a car wash that recycles the water, rather than
washing at home with the hose.
8. Cut your showers short. Older shower heads can use as
much as 5 gallons of water per minute. Speed things up in the
shower for some serious water savings.
9. Choose efficient fixtures. Aerating your faucets, investing
in a low-flow toilet, choosing efficient shower heads, and opting
for a Water Sense rated dishwasher and washing machine can
add up to big water savings.
11-37

38.

10. Shrink your lawn. Even better: lose the
lawn completely. Instead, opt for a xeriscaped landscape
that incorporates water wise ground cover, succulents, and
other plants that thrive in drought conditions.
11. Don’t run the dishwasher or washing machine
until they’re full. Those half-loads add up to gallons and
gallons of wasted water.
12. Keep an eye on your bill to spot leaks. If your water
bill spikes suddenly, there’s a good chance that a leak is
the culprit. Call in a plumber to check your lines to save
water and cash!
13. Install a rain barrel. Rainwater harvesting is a great
way to keep your plants hydrated without turning on the
hose or sprinkler.
11-38

39.

14. Flush with less. Older toilets use a lot of water.
You can reduce your usage by sinking a half gallon jug
of water in the toilet tank. Do NOT use a brick, because
it will break down and the sediment can damage your
tank.
15. Water in the early morning. You’ll need less
water, since cooler morning temperatures mean losing
less water to evaporation. It’s not a great idea to water
in the evenings, since this can promote mold growth.
16. Hand-washing a lot of dishes? Fill up your sink
with water, instead of letting it run the whole time that
you’re scrubbing.
11-39

40.

17. Use less electricity. Power plants use thousands of
gallons of water to cool. Do your part to conserve power, and
you’re indirectly saving water, too!
18. Wash Fido outdoors. That way, you’re watering your
yard while you’re cleaning your pup. Just make sure that the
soap you’re using isn’t harmful to your plants!
19. Skip the shower from time to time. Do you really
need to shower multiple times a day or even daily? Skipping
even one shower a week adds up to big water savings.
20. Re-use grey water. Check to make sure that this is
legal where you live, but in some areas you can do things like
re-route the runoff from your clothes washer and use that
water for things like flushing the toilet.
http://www.care2.com/greenliving/20-ways-to-conserve-water-at-home.html
11-40