Chapter 0 introduction to water resources.ppt

Chapter 0
Introduction to Water
Resources
Prof. Dr. Ali El-Naqa
Hashemite University
June 2013

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]

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

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)

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)

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)

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)

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)

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)

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.

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.

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.

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

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.

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.

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.

 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.

 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.

 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.

 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.

 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

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.

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.

 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.

Soil and water problems, and some ways to address
them

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.

 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.

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

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)

Global Water Cycle
Principal sources
of fresh water for
human activities
(44,800 km3/yr)

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

Population and Water Use
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
1950 1960 1970 1980 1990 2000 2010 2020
W ithdrawal (km 3/yr)
Population (m illion)
global freshwater use is ~4000 km3/year
~10% of the renewable supply (44,800km3/year)

Water Cycle Diagram
Global Water Security – an engineering perspective
The Royal Academy of Engineering, 2010

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

Water Use by Sector

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)

Access to Safe Water2009: 800 million people lacked access to an “improved” water sources.

Access to Sanitation
2009: more than 2 billion people lacked access to basic sanitation facilities

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

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%.

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

Poverty in Sub-Saharan Africa

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

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

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

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

Water Scarcity (2008)
In 2008, over 1.54 billion people suffered from water stress

Water Scarcity (2030)
By 2030, 3.3 billion people will live “water stress” conditions

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

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/]

Water Availability - USA
http://pubs.usgs.gov/circ/2004/circ1268/pdf/circular1268.pdf

Water Use - USA
http://pubs.usgs.gov/circ/2004/circ1268/index.html

Trends
http://pubs.usgs.gov/circ/2004/circ1268/index.html

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.

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.

Girl Carrying Well Water over Dried
Out Earth during a Severe Drought
in India

WATER’S IMPORTANCE, AVAILABILITY,
AND RENEWAL
 Comparison of
population sizes and
shares of the world’s
freshwater among the
continents.

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.

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

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%).

Average Annual Precipitation and
Major Rivers, Water-Deficit
Regions in U.S.
Fig 13-4

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

Fig. 13-6, p. 319
Europe Asia
North
America
Africa
South
America Australia
Stress
High None

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

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.

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.

Other Effects of Groundwater Overpumping
 Groundwater
overpumping can
cause land to sink, and
contaminate
freshwater aquifers
near coastal areas with
saltwater.

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

Natural Capital Degradation:
Irrigation in Saudi Arabia Using an
Aquifer

Natural Capital Degradation: Areas
of Greatest Aquifer Depletion in
the U.S.
Fig 13-9

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

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.

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)

 Advantages
 Increase the reliable runoff available
 Reduce flooding
 Grow crops in arid regions

 Disadvantages
 Displaces people
 Flooded regions
 Impaired ecological services of rivers
 Loss of plant and animal species
 Fill up with sediment within 50 years

Advantages and Disadvantages of
Large Dams and Reservoirs
Fig 13-12

Matilija Dam Removal Project
Click for report

The Colorado River Basin
Fig 13-14

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

Aerial View of Glen Canyon Dam
Across the Colorado River and Lake
Powell

The Flow of the Colorado River
Measured at Its Mouth Has
Dropped Sharply

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

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?

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.

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

Natural Capital Degradation: The
Aral Sea, Shrinking Freshwater Lake
1976 2006

Oxnard water suppliers
United Water
Calleguas Municipal
City of Oxnard

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.

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

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

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.

Reducing Water Waste Has Many
Benefits (1)
 Water conservation
 Improves irrigation efficiency
 Improves collection efficiency
 Uses less in homes and businesses

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.

Solutions: Reducing Irrigation
Water Waste
Fig 13-21

Solutions: Reducing Water Waste
Fig 13-22

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

How can you save water at
home?
Click for Family Water Audit

What Can You Do? Water Use and
Waste
Fig 13-24

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.

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

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

Natural Capital Degradation:
Hillside Before and After
Deforestation
Fig 13-25

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

Chapter 0 introduction to water resources.ppt

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