2. The blue Planet – How come we
lack of sufficient Water Supply?
2
???
Source:
http://omiusajpic.org/files/2011/05/2935018067_cec6254493.jpg
[Accessed: 30.01.2012]
Source: http://true101story.com/wp-
content/uploads/2010/04/eath-hands.jpg [Accessed:
30.01.2012]
3. What is Water Used For?
3
Agricultural
•Irrigation
•Livestock farming
Industrial
•Production of goods
and energy
•Transportation of
goods
•Process water
Domestic
• Drinking water
• Food preparation
• Sanitation
• Personal hygiene
• Cultural asset
• Gardening, Car
wash
ECOSYSTEMHUMANUSE
Plants
Animals
Photosynthesis
SoilsAquatic Systems
4. Think in Cycles rather than in
linear Processes
4
he Global Water Cycle
• The energy of the sun
constantly transforms the
water from solid (ice) to
liquid (water) to gaseous
(vapour)
• Constant transformation
puts the water into motion
and hence activates the
global water cycle
• Characteristics of the
cycle:
Permanent circulation
Renewable resourceSource: OWENS (2006)
5. The blue Planet?
70% of the earth’s surface is covered by water. (PIDWIRNY 2006)
2.5% is freshwater whereas a fifth is easily accessible for
human use. (INFORESOURCES FOCUS 2006)
only 0.5% of global water resources are usable
5
3. Freshwater Resources
Source: WBCSD (2009)
6. Disparities
Distribution of freshwater resources is characterized
by
strong regional differences
annual and seasonal variation (WWAP 2003)
Water Scarcity Index
6
Freshwater Distribution
Source: REKACEWICZ (2009)
7. We do influence the
hydrological Cycle substantially
Main drivers for the increasing pressure on water
resources:
Population growth
Increasing living standards
Urbanisation
Influences On the Water Cycle in Cities
7
Human Influence on the Water Cycle
Source: AUCKLAND CITY COUNCIL (2010)
8. Where the Water ends up being
used
The consumption pattern of water use is influenced
by:
Living standards
Climate conditions
Composition of water use in different countries
8
Source: WBCSD (2009)
9. Increasing Water Scarcity
9
Consequences of Water Use
Drivers:
• Population growth
• Change in living standards
• Uncontrolled pollution
• Climate change
Growing
water scarcity
in various regions of the
world
As of today, 1.2 billion of the
world’s population are
affected by water scarcity
(INFORESOURCES FOCUS 2006)
(WBCSD 2009)
10. What are drylands?
Different people define drylands in different ways.
In terms of the absolute amount of rainfall. For example, the
Convention to Combat Desertification defines drylands as areas with
between 0 and 600 mm of rainfall per year, depending on altitude and
latitude.
In terms of the length of the wet season and the temperature. For
example, areas with less that three months of enough moisture to
support plant growth, and with an average temperature of at least 80°
Fahrenheit (27°C).
By comparing the annual rainfall with the amount of ‘potential
evapotranspiration’ (roughly, the amount of water that evaporates from
a pond or a well-irrigated field in one year). One definition is those
areas wherethe rainfall is less than 40% of the potential
evapotranspiration.
11. What are drylands?
In terms of vegetation. Drylands are areas where conditions favour
perennial grasses rather than annual cereals. Rainfed cropping
therefore has an inherent risk of failure.
In terms of land use. Some farming systems are more sensitive to
drought than others: for example, cattle in wetter areas may not eat dry
grass during a drought.
Pastoralists may regard grazing areas as drylands, in contrast to the
wetter areas, usually highlands, where crops are grown.
12. What are drylands?
The definition of dryland varies from country to country. For example,
most of Uganda has relatively high rainfall. If the maize crops fail once
in five years, people regard the area as dryland.
Such a definition is of little use in countries such as lowland Kenya or
Ethiopia, where rainfall levels are generally much lower. Some 80% of
Kenya is classified as dryland.
Some areas normally regarded as wet may in fact be dryland. For
example, not all the East African highlands are wet. Certain areas on
the shores of Lake Victoria lie in a rain shadow and receive only 600
mm of rain a year.
There is no firm boundary between dryland and wetter areas. One
grades into the other, and the boundary changes from year to year.
Prolonged drought, unseasonal rains and other climate changes may
mean the area expands or contracts.
13. Categories of drylands
Drylands are not homogeneous: different categories exist.
Understanding this is important to identify whether opportunities
exist to change or develop the dominant pastoral production system.
Two broad types of dryland can be distinguished: arid and semi-arid;
and subhumid, wetter drylands. The dividing line is often put at 600
mm of rain per year
14. Arid and semi-arid drylands
In these areas rainfall is the limiting factor for the condition of the
vegetation. The number of cattle grazing has no lasting negative effect
on the vegetation.
Overgrazing is not a problem. Droughts, when they occur, cause the
cattle to die, keeping numbers down. The vegetation is very resilient;
even after a serious drought, it is able to restore itself.
The concept of ‘carrying capacity’ does not apply. In these areas,
pastoralists and their livestock dominate. It is not advisable to replace
the pastoral production system as it already uses all available resources
to a maximum.
15.
16.
17. Wetter drylands
In these areas the condition of the vegetation depends on the number of
cattle. Overgrazing may occur when their numbers exceed the so-called
carrying capacity.
This damages the vegetation, which is not able to regrow after a serious
drought. Despite the high risks, the wetter drylands are increasingly used to
grow crops.
It may be possible to develop new land-use systems that combine various uses.
The aim should be to develop a system that is more productive than the
pastoral system it replaces.
18. Characteristics of drylands
Natural capital
Rainfall The rainfall is low, erratic and scattered, and is concentrated in a few
heavy storms. The rains may be delayed, and droughts are frequent. Rains may
occur at times when they do not benefit crops in the field.
Soils The soils are thin and easily eroded. They are low in organic matter
(less than 2%) and dry out quickly. Some soil types occur only in dryland areas.
Within the drylands there are scattered patches with better soils or a wetter
climate.
Vegetation The vegetation is sparse, leaving a large proportion of the soil
surface exposed. This allows rain to compact the surface, forming a crust
which stops water from seeping into the soil. The water runs off instead,
causing erosion and flash floods.
19. Characteristics of drylands
Physical capital
Infrastructure There are few roads, and permanent settlements are sparse.
Markets, abattoirs and food storage and transport facilities are poorly
developed. Irrigation from groundwater or dams has converted some
otherwise dry areas to more productive cropland – while preventing
pastoralists from grazing their animals on this land.
Farming systems The major dryland crops are sorghum, pearl millet,
finger millet, short-season maize, cowpeas and haricot beans. In wetter areas
or land with irrigation, farmers also grow cassava and pigeonpeas for local
consumption, and beans and Asian vegetables for export. Livestock herders
keep cattle, sheep, goats, camels and donkeys; sedentary farmers may also keep
chickens. Camels, goats and donkeys are hardier than cattle and sheep.
20. Characteristics of drylands
Human capital
Indigenous knowledge Pastoralists have a rich store of indigenous
knowledge about their environment and animals, how to predict drought,
where to find pastures and water, and how to prevent and treat livestock
diseases. Indigenous sedentary farmers have equivalent knowledge about their
crops and soils. However, new settlers may not be as familiar with the
problems and opportunities in the drylands.
Education Most people in the drylands are poorly educated. Illiteracy rates
are high, especially among women. Children often attend boarding schools in
the towns, and may be reluctant to return to their original lifestyles after
graduating. Dropout rates are high.
21. Characteristics of drylands
Social capital
Lifestyles The majority of people depend directly on the land. There are
two broad groups: nomadic or semi-nomadic pastoralists, and sedentary
farmers who grow crops. Pastoralists and sedentary farmers may belong to
different ethnic groups, each with its own culture. However, pastoralists and
crop farmers are not necessarily distinct: ‘agropastoralists’ may also grow crops
in addition to keeping livestock, and crop farmers also keep livestock and may
move with them if required.
Mobility Pastoralists, in particular, are highly mobile. They move with their
herds in search of grazing and water. They take advantage of the scattered
rainfall in a way that no other production system does. They pay little attention
to government, and often cross district and international boundaries.
22. Characteristics of drylands
Financial capital
Poverty The vast majority of both pastoralists and sedentary farmers are
poor. They have limited cash. Pastoralists tend to have more capital (in the
form of animals) than do sedentary farmers. A few people are wealthier: they
own larger herds or more (or more fertile) land.
Income sources Pastoralists are commercially oriented: they sell animals in
order to buy food (grains, sugar, tea) and things they cannot make themselves
(cooking utensils, clothes), to pay school, veterinary and medical fees, and to
buyfood in an emergency. However, pastoralists often lack a market for their
animals. Crop farmers are more subsistence-oriented: they grow most of their
own food. Many men seek employment in the cities for at least part of the
year.
23. Characteristics of drylands
Changes in the drylands
Population The human population is rising, both by natural increase and by
immigration from more densely populated high-potential areas. This puts extra pressure
on the limited resources. Intensive cultivation degrades the soils, and overgrazing
depletes the ground cover.
Climate In recent years, the climate has been in a state of flux. Droughts have
become more frequent, and rains fall at unusual times of the year. These changes may
be caused by global warming.
Land use and ownership Settlers erect fences and encroach on traditional grazing
lands. Irrigation schemes are built in areas with better soils, which are often the same
areas used by pastoralists as dry-season grazing. Common land is increasingly claimed
as private property, encouraging a change from pastoralism to crop farming, and
removing the best land from the pastoralists. Powerful, city based individuals have
grabbed large tracts of land
24. Water
Water is the principal limiting factor. The low, unreliable rainfall means that
often very little moisture is available for plant growth. The rains may start on
time but then stop again, killing seedlings.
Or the rains may be late, making the season too short for sustainable growth
during the crucial phase of flowering. Recurrent droughts cause frequent crop
failures. Farmers respond by using various ways to conserve rainfall and store
it in the root zone.
25. Soil and water conservation
A significant percentage of rainwater in dryland areas is lost as surface runoff.
Much of the rest evaporates or percolates deep into the ground where plant
roots cannot reach it. Plants quickly absorb the little moisture still in the soil,
and soon the ground becomes dry, incapable of supporting crops.
Erosion is a related problem.Dryland soils are often thin, have poor soil
structure, are low in organic matter and are bare of vegetation. Crusts form on
the surface of many soils, reducing the amount of water that can seep into the
soil. The water runs off easily, forming gullies and carrying valuable topsoil
with it.
27. Soil and water conservation
Crop farmers cannot afford to lose the little moisture and soil there is, so they
have for centuries used indigenous conservation techniques. These range from
stone terraces in mountainous areas to tillage practices in flat areas. They focus
on conserving moisture to improve crop yields. However, the main priority
(from the farmers’ viewpoint) is higher production, with soil conservation
coming second.
Only crop farmers are willing to invest in conservation measures; pastoralists
are not very interested because they are mobile. Degradation of grazing lands
is a problem in wetter areas with many people and livestock, and around
communal watering points. Degradation is caused by continuous grazing and
tracking, shifting cultivation, indiscriminate cutting of trees and uncontrolled
burning.
29. Irrigation
Rainfall in the drylands is usually not enough to guarantee reliable, steady
production of crops. So some kind of irrigation is helpful, either to provide
extra water to a rainfed crop, or to water a second crop during the dry season.
If water is available, the dryland climate favours irrigated crops. High
temperatures stimulate plant growth. Pests are few due to the low humidity.
The extended dry season and the lack of a winter enables growers to produce
crops when demand is high in the export market.
30. Soil and water conservation
For small-scale crop farmers, irrigation may mean the difference between a
secure harvest and no yield at all.
There is a wide range of traditional small-scale irrigation practices, mostly
along small rivers in mountainous terrain, along riverbeds, using residual
moisture in valley bottoms, or tapping shallow groundwater.
Farmers using these practices use very few external inputs and often show a
remarkable talent for improvisation when confronted with new situations.
New techniques, such as drip irrigation (page 104) and manually operated
treadle pumps, have shown promise on small farms ranging from small
gardens (15–30 m2) to over 1.5 ha.
Irrigated areas are generally small, from under 1 ha to 20–40 ha. Most farmers
own less than 1 ha of irrigated land. The fields are located as close as possible
to the source of water.
31. Water sources
Irrigated farming is very different from rainfed farming. In rainfed farming,
the farmer prepares the field and waits for the rain to come and make the crop
flourish. With irrigation, the farmer must obtain and manage the water. This
can take a lot of time and money.
The cropping pattern is closely related to the amount of water and how it is
obtained. The size of the irrigated area depends on how much water is
available.
Small perennial or seasonal rivers are the main sources of irrigation water.
Water can be lifted directly from the river, or diverted into irrigation canals or
pipes using dams or weirs. Wells can be dug to tap groundwater, which can be
lifted up by hand or with pumps. In some places, it is possible to tap water
beneath dry stream beds. Rain and runoff water can collected and stored in
small reservoirs or tanks
32. Global Water Resources
Only this portion
is renewable
saline (salt) water: 10 to 100g/L (34g/L)
brackish water: 1 to 10g/L (treatable)
Fresh water: <1g/L (drinkable)
35. The Importance of Water
Human / Environmental Health
Dignity / Gender Equity
Economic Growth / Poverty Reduction
Environment and Ecosystem Services
Food Security / Crops and Fisheries
Energy Generation / Flood Control
Conflict Prevention and Mitigation
Summary of the World Water Crisis and USG Investments in the Water Sector, USAID, 2010
36. Global Water Resources
Only this portion
is renewable
saline (salt) water: 10 to 100g/L (34g/L)
brackish water: 1 to 10g/L (treatable)
Fresh water: <1g/L (drinkable)
39. The Importance of Water
Human / Environmental Health
Dignity / Gender Equity
Economic Growth / Poverty Reduction
Environment and Ecosystem Services
Food Security / Crops and Fisheries
Energy Generation / Flood Control
Conflict Prevention and Mitigation
Summary of the World Water Crisis and USG Investments in the Water Sector, USAID, 2010
40. Population and Water Use
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
1950 1960 1970 1980 1990 2000 2010 2020
Withdrawal (km3/yr)
Population (million)
global freshwater use is ~4000 km3/year
~10% of the renewable supply (44,800km3/year)
41. Water Cycle Diagram
Global Water Security – an engineering perspective
The Royal Academy of Engineering, 2010
43. Global Water Withdrawals
World Water Assessment Programme. 2009. The United Nations World Water Development Report 3: Water in a Changing World.
Paris: UNESCO, and London: Earthscan
45. Water Use by Sector
World Water Assessment Programme. 2009. The United Nations World Water Development Report 3: Water in a Changing World.
Paris: UNESCO, and London: Earthscan
46. Water Supply and Sanitation
Supply (2002)
1.1 billion people lacked access to improved water sources (17%
of global population)
Nearly two thirds live in Asia (733 million people)
42% of Sub-Saharan Africa is without improved water
Sanitation (2002)
2.6 billion people lacked access to improved sanitation (42% of
global population)
Over half of those live in China + India (~ 1.5 billion people)
64% of Sub-Saharan Africa without sanitation coverage
69% of rural dwellers in developing countries without access to
improved sanitation (27% for urban dwellers)
47. Access to Safe Water2009: 800 million people lacked access to an “improved” water sources.
Summary of the World Water Crisis and USG Investments in the Water Sector, USAID, 2010
48. Access to Sanitation
Summary of the World Water Crisis and USG Investments in the Water Sector, USAID, 2010
2009: more than 2 billion people lacked access to basic sanitation facilities
49. Water Supply and Sanitation
Diarrhea (2004)
1.8 million people die every year from diarrheal
diseases (including cholera)
90% are children under 5 in developing countries
88% of diarrheal disease is attributed to unsafe
water supply, inadequate sanitation and hygiene
Improved access to water supply and sanitation
can reduce diarrhea morbidity
Water supply: 6% – 25% (108,000 – 450,000 people)
Sanitation: 32% (576,000 people)
Total: 1.026 million
http://www.who.int/water_sanitation_health/diseases/burden/en/index.html
50. Diarrhea is the Second Leading Cause of Death
in Children Worldwide
2008: Nearly 1.8 million children under the age of 5 died from diarrhea.
This can be reduced by 30-40%.
Summary of the World Water Crisis and USG Investments in the Water Sector, USAID, 2010
51. Poverty and Development
Two thirds of the 884 million people (2009) without access
to safe drinking water live on less than $2 per day.
The urban poor population is large and growing rapidly.
Half of urban residents live in slums where the no formal
access to water or sanitation is typical.
> 1 billion people live in extreme poverty (< $1 a day)
http://www.unmillenniumproject.org/resources/fastfacts_e.htm
http://stats.oecd.org/qwids
52. Poverty in Sub-Saharan Africa
World Water Assessment Programme. 2009. The United Nations World Water Development Report 3: Water in a Changing World.
Paris: UNESCO, and London: Earthscan
53. Water, Sanitation & Poverty
World Water Assessment Programme. 2009.
The United Nations World Water Development Report 3:
Water in a Changing World. Paris: UNESCO, and London: Earthscan
54. Domestic Water Use Survival = 5 L/day
Drinking, cooking, bathing, and sanitation = 50 L
United States = 250 to 300 L
Netherlands = 104 L
Somalia = 9 L
* L/c/d = liters per person per day
55. Water Stress Index Based on human consumption
linked to population growth
Domestic requirement:
About 100 L/c/d = 40 m3/c/yr
Associated agricultural, industrial & energy need:
About 20 x 40 m3/c/yr = 800 m3/c/yr
Total need:
840 m3/c/yr
About 1000 m3/c/yr
56. Water Stress Index
Water availability below 1,000 m3/c/yr
chronic water related problems impeding development and
harming human health
Water sufficiency: >1700 m3/c/yr
Water stress: <1700 m3/c/yr
Water scarcity: <1000 m3/c/yr
58. Water Scarcity (2008)
Summary of the World Water Crisis and USG Investments in the Water Sector, USAID, 2010
In 2008, over 1.54 billion people suffered from water stress
59. Water Scarcity (2030)
Summary of the World Water Crisis and USG Investments in the Water Sector, USAID, 2010
By 2030, 3.3 billion people will live “water stress” conditions
60. Units 1 ft = 0.3048 m
1 m3 = 28.3168x10 -3 ft3
1 m3 = 35.3147 ft3
1 ha = 10,000 m2
1 acre = 43,560 ft2
= 0.4047 ha
= 4047 m2
1 gal = 3.785x10 -3 m3
= 3.785 L
1 m3 = 8.11x10-4 af
109 m3 = 8.11x105 af
1 km3 = 0.811 maf
1 m3 = 264 gal
109 m3 = 264x109 gal
1 km3 = 264 bg
1 km3/yr = 0.7234 bgd
61. Water Availability - USA
USA
Area 9.36 mln km2
Population 304 mln, 2008
Water Resources (bln m3/yr) Water Availability (1000 m3/yr)
Trans-
boundary Local Total per km2 per capita
Minimum 107 2058 2165 231 7
Average 148 2930 3078 329 10
Maximum 178 3864 4042 432 13
From: Shiklomanov http://espejo.unesco.org.uy/]
62. Water Availability - USA
http://pubs.usgs.gov/circ/2004/circ1268/pdf/circular1268.pdf
63. Water Use - USA
http://pubs.usgs.gov/circ/2004/circ1268/index.html
66. 13-1 Will We Have Enough Usable Water?
Concept 13-1A We are using available freshwater
unsustainably by wasting it, polluting it, and charging
too little for this irreplaceable natural resource.
Concept 13-1B One of every six people does not have
sufficient access to clean water, and this situation will
almost certainly get worse.
67. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
Water keeps us alive, moderates climate, sculpts the
land, removes and dilutes wastes and pollutants, and
moves continually through the hydrologic cycle.
Only about 0.02% of the earth’s water supply is
available to us as liquid freshwater.
68. Girl Carrying Well Water over Dried
Out Earth during a Severe Drought
in India
70. WATER’S IMPORTANCE, AVAILABILITY,
AND RENEWAL
Some precipitation infiltrates the ground and is stored
in soil and rock (groundwater).
Water that does not sink into the ground or evaporate
into the air runs off (surface runoff) into bodies of
water.
The land from which the surface water drains into a
body of water is called its watershed or drainage
basin.
71. Fig. 13-3, p. 316
Unconfined Aquifer Recharge Area
Precipitation Evaporation and transpiration Evaporation
Confined
Recharge
Area Runoff
Flowing
artesian well
Well
requiring
a pump Stream
Infiltration
Water
table
Lake
Infiltration
Less permeable
material such as
clay
72. WATER’S IMPORTANCE, AVAILABILITY,
AND RENEWAL
We currently use more than half of the world’s reliable
runoff of surface water and could be using 70-90% by
2025.
About 70% of the water we withdraw from rivers,
lakes, and aquifers is not returned to these sources.
Irrigation is the biggest user of water (70%), followed
by industries (20%) and cities and residences (10%).
74. Fig. 13-5, p. 318
Substantial conflict potential
Highly likely conflict potential
Unmet rural water needs
Moderate conflict potential
Washington
Oregon
Montana
North
Dakota
Idaho South
Dakota
Wyoming
Nevada Nebraska
Utah
Colorado
Kansas
California
Oklahoma
New
Mexico
Texas
Arizona
Water Hot Spots
75. Fig. 13-6, p. 319
Europe Asia
North
America
Africa
South
America Australia
Stress
High None
76. Long-Term Severe Drought Is
Increasing
Causes
Extended period of below-normal rainfall
Diminished groundwater
Harmful environmental effects
Dries out soils
Reduces stream flows
Decreases tree growth and biomass
Lowers net primary productivity and crop yields
Shift in biomes
77. Case Study: Who Should Own and Manage
Freshwater Resources
There is controversy over whether water supplies
should be owned and managed by governments or by
private corporations.
European-based water companies aim to control 70%
of the U.S. water supply by buying up water companies
and entering into agreements with cities to manage
water supplies.
78. 13-2 Is Extracting Groundwater
the Answer?
Concept 13-2 Groundwater that is used to supply cities
and grow food is being pumped from aquifers in some
areas faster than it is renewed by precipitation.
79. Other Effects of Groundwater Overpumping
Groundwater
overpumping can
cause land to sink, and
contaminate
freshwater aquifers
near coastal areas with
saltwater.
80. Fig. 13-7, p. 321
TRADE-OFFS
Withdrawing Groundwater
Advantages Disadvantages
Useful for drinking
and irrigation
Aquifer depletion
from overpumping
Available year-round
Sinking of land
(subsidence) from
overpumping
Exists almost
everywhere
Aquifers polluted for
decades or centuries
Renewable if not
overpumped or
contaminated
Saltwater intrusion into
drinking water supplies
near coastal areas
No evaporation
losses
Reduced water flows
into surface waters
Cheaper to extract
than most surface
waters
Increased cost and
contamination from
deeper wells
83. Fig. 13-11, p. 324
SOLUTIONS
Groundwater Depletion
Prevention Control
Waste less water Raise price of water
to discourage waste
Subsidize water
conservation
Tax water pumped
from wells near
surface waters
Limit number of
wells
Set and enforce
minimum stream
flow levels
Do not grow water-
intensive crops in
dry areas
Divert surface water
in wet years to
recharge aquifers
84. 13-3 Is Building More Dams the
Answer?
Concept 13-3 Building dam and reservoir systems has
greatly increased water supplies in some areas, but it
has disrupted ecosystems and displaced people.
85. Large Dams and Reservoirs Have
Advantages and Disadvantages (1)
Main goals of a dam and reservoir system
Capture and store runoff
Release runoff as needed to control:
Floods
Generate electricity
Supply irrigation water
Recreation (reservoirs)
86. Large Dams and Reservoirs Have
Advantages and Disadvantages (2)
Advantages
Increase the reliable runoff available
Reduce flooding
Grow crops in arid regions
87. Large Dams and Reservoirs Have
Advantages and Disadvantages (3)
Disadvantages
Displaces people
Flooded regions
Impaired ecological services of rivers
Loss of plant and animal species
Fill up with sediment within 50 years
91. Case Study: The Colorado River
Basin— An Overtapped Resource
(3)
Four Major problems
Colorado River basin has very dry lands
Modest flow of water for its size
Legal pacts allocated more water for human use than it
can supply
Amount of water flowing to the mouth of the river has
dropped
92. Aerial View of Glen Canyon Dam
Across the Colorado River and Lake
Powell
93. The Flow of the Colorado River
Measured at Its Mouth Has
Dropped Sharply
94. Case Study: China’s Three
Gorges Dam (1)
World’s largest hydroelectric dam and reservoir
2 km long across the Yangtze River
Benefits
Electricity-producing potential is huge (18 large power
plants)
Holds back the Yangtze River floodwaters
Allows cargo-carrying ships
95. Case Study: China’s Three
Gorges Dam (2)
Harmful effects
Displaces about 5.4 million people
Built over a seismic fault
Significance?
Rotting plant and animal matter producing CH4
Worse than CO2 emissions
Will the Yangtze River become a sewer?
96. 13-4 Is Transferring Water from
One Place to Another the Answer?
Concept 13-4 Transferring water from one place to
another has greatly increased water supplies in some
areas, but it has also disrupted ecosystems.
97. Fig. 13-17, p. 330
CALIFORNIA
Shasta Lake NEVADA
Sacramento
River
UTAH
North Bay
Aqueduct
Feather
River
Lake Tahoe
San Francisco
Sacramento
South Bay
Aqueduct
Hoover Dam
and Reservoir
(Lake Mead)
Los Angeles
Aqueduct
Colorado
River
California Aqueduct
Colorado River
Aqueduct Central Arizona
Project
ARIZONA
Fresno
Santa Barbara
Los Angeles
San Diego
Salton Sea
Phoenix
Tucson
MEXICO
San Luis Dam
and Reservoir
Oroville Dam and
Reservoir
100. 13-5 Is Converting Salty Seawater
to Freshwater the Answer?
Concept 13-5 We can convert salty ocean water to
freshwater, but the cost is high, and the resulting salty
brine must be disposed of without harming aquatic or
terrestrial ecosystems.
101. Removing Salt from Seawater
Seems Promising but Is Costly (1)
Desalination
Distillation
Reverse osmosis, microfiltration
15,000 plants in 125 countries
Saudi Arabia: highest number
Click for link to Desal Response Group
102. Removing Salt from Seawater
Seems Promising but Is Costly (2)
Problems
High cost and energy footprint
Keeps down algal growth and kills many marine
organisms
Large quantity of brine wastes
Click for Oxnard’s GREAT RO plant info
103. 13-6 How Can We Use Water More
Sustainably?
Concept 13-6 We can use water more sustainably by
cutting water waste, raising water prices, slowing
population growth, and protecting aquifers, forests,
and other ecosystems that store and release water.
104. Reducing Water Waste Has Many
Benefits (1)
Water conservation
Improves irrigation efficiency
Improves collection efficiency
Uses less in homes and businesses
105. Fig. 13-20, p. 335
Stepped Art
Gravity flow
(efficiency 60% and 80% with surge valves)
Water usually comes from an
aqueduct system or a nearby river.
Drip irrigation
(efficiency 90–95%)
Above- or below-ground
pipes or tubes deliver water
to individual plant roots.
Center pivot
(efficiency 80% with low-pressure
sprinkler and 90–95% with LEPA
sprinkler)
Water usually pumped from
underground and sprayed
from mobile boom with
sprinklers.
108. Fig. 13-23, p. 337
SOLUTIONS
Sustainable Water Use
Waste less water and subsidize
water conservation
Preserve water quality
Protect forests, wetlands,
mountain glaciers, watersheds,
and other natural systems that
store and release water
Get agreements among regions
and countries sharing surface
water resources
Raise water prices
Do not deplete aquifers
Slow population growth
109. How can you save water at
home?
Click for Family Water Audit
111. 13-7 How Can We Reduce the
Threat
of Flooding?
Concept 13-7 We can lessen the threat of flooding by
protecting more wetlands and natural vegetation in
watersheds and by not building in areas subject to
frequent flooding.
112. Some Areas Get Too Much Water
from Flooding (1)
Flood plains
Highly productive wetlands
Provide natural flood and erosion control
Maintain high water quality
Recharge groundwater
Benefits of floodplains
Fertile soils
Nearby rivers for use and recreation
Flatlands for urbanization and farming
113. Some Areas Get Too Much Water
from Flooding (2)
Dangers of floodplains and floods
Deadly and destructive
Human activities worsen floods
Failing dams and water diversion
Hurricane Katrina and the Gulf Coast
Removal of coastal wetlands
115. Fig. 13-26, p. 340
SOLUTIONS
Reducing Flood Damage
Prevention Control
Preserve forests on
watersheds
Straighten and
deepen streams
(channelization)
Preserve and restore
wetlands in floodplains
Tax development on
floodplains
Build levees or
floodwalls along
streams
Use floodplains primarily
for recharging aquifers,
sustainable agriculture
and forestry
Build dams
![The blue Planet – How come we
lack of sufficient Water Supply?
2
???
Source:
http://omiusajpic.org/files/2011/05/2935018067_cec6254493.jpg
[Accessed: 30.01.2012]
Source: http://true101story.com/wp-
content/uploads/2010/04/eath-hands.jpg [Accessed:
30.01.2012]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)