Transcript QOD Calculate how many liters of water are wasted in 1 month by a faucet that leaks 2 drops of water per second. (1

QOD
Calculate how many liters of water are
wasted in 1 month by a faucet that leaks 2
drops of water per second.
(1 liter of water equals about 3500 drops)
How many gallons is this?
(1 liter equals 0.265 gallons)
Water Resources
G. Tyler Miller’s
Living in the Environment
13th Edition
Chapter 14
Key Concepts
 The physical properties of water
 Availability of fresh water
 Methods of increasing freshwater supplies
 Using water more efficiently
 Problems associated with flooding
Water’s Unique Properties
Hydrogen bonding
• Major factor in determining
water’s unique properties
Hydrogen bonds
-
-
O
Covalent bonds
H
-
- +
H
+ -
O
H
+
O
H
+
H
+
H
+
Water’s Unique Properties
 Liquid over wide temperature range
• High boiling point 100°C (212°F)
• Low freezing point 0°C (32°F)
 Changes temperature slowly
• Helps protect organisms
• Moderates the earth’s climate
• Excellent coolant
 High heat of evaporation
• Absorbs heat as it changes into water vapor
• Releases heat as vapor condenses
Water’s Unique Properties
 Great dissolving power
•
•
•
•
Carries dissolved nutrients into tissue
Flush waste products out of tissue
All-purpose cleanser
Remove and dilute water-soluble wastes
 pH
• Helps maintain balance between acids and
bases
 Adhesion and cohesion
• Surface tension
• Wetting ability
 Expands when it freezes
• Ice floats
Water: A Vital Resource
Fresh
Water
2.6%
Oceans
and saline
lakes
97.4%
Supply of Water Resources
Freshwater
Readily accessible freshwater
Groundwater
0.592%
Biota
0.0001%
Lakes
0.007%
Ice caps
and glaciers
0.1.984%
0.014%
Soil
moisture
0.005%
Rivers
0.0001%
Atmospheric
water vapor
0.001%
Surface Water
• Surface runoff
– Water flowing off the land into bodies of
water
• Reliable runoff
– One-third of world’s annual runoff
– Represents a stable source of water
• Watershed (Drainage Basin)
– Region from which water drains
Groundwater
Ground Water
Flowing
artesian well
Fig. 14-3 p. 315
Unconfined Aquifer Recharge Area
Precipitation
Evaporation and transpiration
Well requiring a pump
Evaporation
Confined
Recharge Area
Runoff
Aquifer
Stream
Infiltration Water table
Lake
Infiltration
Unconfined aquifer
Less permeable material
such as clay
Confined aquifer
Confirming permeable rock layer
Use of Water Resources
 Humans use about 50% of reliable runoff
•
•
•
•
Agriculture
Industry
Domestic
Power Plants
United States
Power
cooling
38%
Agriculture
41%
Industry 11%
Public 10%
5,500
Water use (cubic kilometers per year)
5,000
Total use
4,500
4,000
3,500
3,000
2,500
2,000
Agricultural use
1,500
Industrial use
1,000
Domestic use
500
1900
1920
1940
1960
Year
1980
2000
Water in the
United States
• Average
precipitation
(top) in relation
to water-deficit
regions and
• their proximity
to metropolitan
areas (bottom).
Too Little Water
1) Dry climate
•
Air circulation
patterns
2) Drought
•
•
•
21 days+
Precipitation <70%
Increased evaporation
•
Drying of the soil
•
Low per capita
availability
Caused by increased
population
Limited runoff levels
3) Desiccation
4) Water stress
•
•
Acute shortage
Adequate supply
Shortage
Metropolitan regions with
population greater than 1 million
Water stressed –
reliable runoff per
person below 1700
cu meters per year
Water scarcity – per
capita availability
below 1000 cu
meter per year
500 million people live in
countries that are either water
stressed or water scarce
• limited access (live far away)
• arrives during short periods
• hydrological poverty
–Collect water from unsafe sources
–Purchase from private vendor
Increasing Fresh Water
Supplies
1. Build dams and reservoirs to store
runoff
2. Bring surface water from another
area
3. Withdraw groundwater.
4. Convert salt water to fresh water
5. Waste less water
6. Import food to reduce water use
Using Dams and
Reservoirs to Supply More
Water
(To Dam or Not To Dam)
Provides water
for year-round
irrigation of
cropland
Provides
water for
drinking
Reservoir is
useful for
recreation
and fishing
Can produce
cheap
electricity
(hydropower)
Downstream
flooding is
reduced
Flooded land
destroys forests
or cropland and
displaces people
Large losses of
water through
evaporation
Downstream
cropland and
estuaries are
deprived of
nutrient-rich silt
Risk of
failure and
devastating
downstream
flooding
Migration and
spawning of
some fish are
disrupted
Fig. 14-13a, p. 317
Ecological Services of Rivers
• Deliver nutrients to the sea which helps
to sustain coastal fisheries
• Deposit silt that maintains deltas
• Purify water
• Renew and nourish wetlands
• Provide habitats for aquatic life
• Conserve species diversity
Beijing
RUSSIA
YELLOW
SEA
MONGOLIA
CHINA
Shanghai
Jailing
River
Wunan
Yichang
Chongquing
CHINA
Reservoir
NEPAL
Yangtze
River
BHUTAN
BANGLADESH
INDIA
Three
Gorges
Dam
VIETNAM
BURMA LAOS
PACIFIC
OCEAN
China’s Three Gorges Dam
EAST
CHINA
SEA
Case Study: The Colorado
Basin – an Overtapped
Resource
• Lake Powell, is
the second
largest reservoir
in the U.S.
• It hosts one of the
hydroelectric
plants located on
the Colorado
River.
IDAHO
WYOMING
Dam
Aqueduct
or canal
Salt Lake City
Grand Junction
Upper Basin
Denver
Lower Basin
UPPER
BASIN
UTAH
COLORADO
Lake
Powell
Grand
Canyon
Las Vegas
Glen
Canyon
Dam
NEW MEXICO
Boulder City
ARIZONA
CALIFORNIA
Albuquerque
Los
Angeles Palm
Springs
LOWER
BASIN
Phoenix
San Diego
Yuma
Mexicali
All-American
Canal
Gulf of
California
Tucson
0
100 mi.
0
150 km
MEXICO
The
Colorado
River
Basin
Transferring Water from One Place
to Another
Watershed transfer
CALIFORNIA
NEVADA
 California
Water Project
 Central Arizona
Project
 James Bay
(Canada)
Sacramento
River
North Bay
Aqueduct
Shasta Lake
UTAH
Sacramento
San Francisco
South Bay
Aqueduct
Fresno
Los Angeles
Aqueduct
California Aqueduct
Los Angeles
Colorado
River
ARIZONA
Central Arizona
Project
Phoenix
San Diego Colorado River
Aqueduct
Tucson
MEXICO
Increasing Fresh Water Supplies
1. Build dams and reservoirs to store
runoff
2. Bring surface water from another
area
3. Withdraw groundwater.
Tapping Groundwater
• Advantages
– Year-round use
– No evaporation losses
– Often less expensive
• Potential Problems!
– Many
Problems with Using Groundwater
1) Water Table Lowering
Original
water table
Initial water table
Cone of
depression
Lowered
water table
Problems with
Using
Groundwater
WYOMING
SOUTH DAKOTA
NEBRASKA
KANSAS
2) Aquifer depletion
COLORADO
• Ogalala Aquifer
OKLAHOMA
NEW MEXICO
Less than 61 meters (200 ft)
61-183 meters (200-600 ft)
More than 183 meters (600 ft)
(as much as 370 meters or 1,200 ft.
in places)
TEXAS
Miles
0
100
0
160
Kilometers
Problems with Using Groundwater
3) Subsidence
– Sinking of land when groundwater
is withdrawn
Other Effects of Groundwater
Overpumping
• Sinkholes form
when the roof of
an underground
cavern collapses
after being
drained of
groundwater.
Problems with Using Groundwater
4) Saltwater intrusion
Major irrigation
well
Well contaminated
with saltwater
Water
table
Sea Level
Salt
water
Fresh
groundwater
aquifer
Interface
Saltwater
Intrusion
Interface
Normal
Interface
Major
irrigation
well
Fresh
groundwater
aquifer
Well contaminated
with saltwater
Water
table
Interface
Saltwater
intrusion
Interface
Normal
interface
Fig. 14-11, p. 315
Problems with Using Groundwater
5) Chemical contamination
6) Reduced stream flow
• Tragedy of the commons
Converting Salt Water to Fresh Water
• Desalination – removing dissolved salts
from ocean water or brackish water.
– Distillation desalination
• Heating salt water until it
evaporates.
– Reverse osmosis desalination
• Salt water is pumped at high
pressure through a thin membrane
Converting Salt Water to Fresh Water
• Desalination – removing dissolved
salts from ocean water or brackish
water.
– Desalination is very expensive
• Larger amounts of energy needed
– Desalination produces large quantities
of wastewater
• waste disposal problem
Making it Rain
• Cloud Seeding
– Water condensation nuclei
– Silver iodide particles
• Limited Success
– Not useful in dry areas
– Potential pollution from cloud seeding
chemicals
– Legal disputes: ownership of clouds
Using Water More Efficiently
• Reduce losses due to leakage
– 60 to75% of water people use is lost!
• Causes of waste
– Water subsidy policy
• Artificially low cost of water
• False sense of abundance
Using Water More Efficiently
• Causes of waste cont.
– Water laws
• Doctrine of riparian rights (East)
– Anyone owning land adjoining stream has right
to water
• Principle of prior appropriation (West)
– First-come, first-served
• Common law governs groundwater
– Subsurface water belongs to whoever owns the
land above it
– Fragmented watershed management
Drip irrigation
(efficiency 90–95%)
Gravity flow
(efficiency 60% and
80% with surge
valves)
Center pivot
(efficiency 80%–95%)
Water usually comes from
an aqueduct system or a
nearby river.
Above- or belowground pipes or tubes
deliver water to
individual plant roots.
Water usually pumped
from underground and
sprayed from mobile
boom with sprinklers.
Fig. 14-18, p. 325
Too Much Water: Floods
 Natural phenomena
 Aggravated by
• heavy rain, melting snow
human
activities
 Renew and replenish
Reservoir
Dam
Levee
Floodplain
Flood
wall
Solutions: Achieving a More
Sustainable Water Future
Efficient irrigation
Water-saving technologies
Improving water management
What Can You Do?
Water Use and Waste
• Use water-saving toilets, showerheads, and faucet aerators.
• Shower instead of taking baths, and take short showers.
• Stop water leaks.
• Turn off sink faucets while brushing teeth, shaving, or washing.
• Flush toilets only when necessary.
• Wash only full loads of clothes or use the lowest water-level for
smaller loads.
• Use recycled (gray) water for lawn, gardens, house plants,
car washing.
• Wash a car from a bucket of soapy water, and use the hose for
rinsing only.
• If you use a commercial car wash, try to find one that recycles its
water.
• Replace your lawn with native plants that need little if any watering
and decorative gravel or rocks.
• Water lawns and gardens in the early morning or evening.
• Sweep or blow off driveways instead of hosing off with water.
• Use drip irrigation and mulch for gardens and flowerbeds.
2002 Free Response Question #2