Mismanagement of river basins,
watersheds and lakes
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Freshwater and the hydrological cycle
Water “hot spots” in the world
How to deal with water scarcity
Global warming and water scarcity
Water “hot spots”
http://news.bbc.co.uk/2/shared/spl/hi/world/03/world_forum/water/html/mexico_city.stm
The Aral Sea in Central Asia was once the world's fourth biggest inland sea, and one of the world's most fertile regions. But economic
mismanagement has turned the area into a toxic desert. The two rivers feeding the sea, the Amu Darya and the Syr Darya, were diverted in a
Soviet scheme to grow cotton. Between 1962 and 1994, the level of the Aral Sea fell by 16 metres.
The surrounding region now has one of the highest infant mortality rates in the world, and anaemia and cancers caused by chemicals blowing
off the dried sea bed are common.
In a desperate attempt to keep their vessels in the
shrinking Aral, channels were dredged to the open
sea. it was a futile exercise, as the sea receded
faster than the channels could be built. The fishing
industry was effectively gone by 1982, and the
canning plant processing frozen fish brought in
from other areas to keep fishermen employed,
folded in 1991.
Of the region's 73 species of birds, 70 of mammals
and 24 of fish, most have either perished or moved
on.
Causes
Lake Chad, once a huge lake straddling the borders of Chad, Niger,
Nigeria and Cameroon, has shrunk by 95% since the mid 1960s. The
region's climate has changed during that time, with the monsoon rains
which previously replenished the lake now greatly reduced.
A recent study blamed human activities combined with local weather
changes, not global warming. It said overgrazing had destroyed the
savannah vegetation which itself influenced the weather patterns.
As the climate has become drier, the demand for water to irrigate food
crops has increased – quadrupling between 1983 and 1994 - depleting
the lake further.
Nine million farmers, fishermen, and herders in the region now face
water shortages, crop failure, livestock deaths, collapsed fisheries, soil
salinity and increasing poverty.
Mexico City is sinking because of the amount of water being
pumped out from beneath its foundations.
One of the largest and most populous cities in the world, it was
once a lush land of lakes. But over the last 500 years the lakes
have been drained and the surrounding forests chopped down.
As the city grew in size, the water problem magnified. With no
adequate drainage system, today rainwater mixes with sewage
and is used for irrigation.
The city is now at serious risk of running out of clean water. An
estimated 40% of the city's water is lost through leaky pipes built
at the turn of the century.
Mexico city (20 million people)
In the last 100 years the city has sunken
more than 9 meters. As a consequence
the walls of the buildings are buckled. 23
steps have recently to be added to the
independence monument (1900).
1 to 4 people have no
access to water.
40% of water from aquifer
is wasted due to
inadequate piping system
River Nile
A United Nations report has predicted that access to water may be the single biggest
cause of conflict and war in Africa in the next 25 years.
Experts have warned that if populations rise as expected in Egypt, Ethiopia and
Sudan - the three countries most dependent on the Nile - competition for its waters
will be intense.
Cairo said in 1991 that it was ready to use force to protect its access to the 7,000kmlong river, which with its tributaries runs through nine countries.
However, recent years have seen Egypt, Ethiopia and Sudan agree to use the river
equitably and apply the principles of sustainable development.
Turkey
Water-rich by Middle-Eastern standards, Turkey has in recent years undertaken an
ambitious project to sell water from its Manavgat river across the region.
It is still vulnerable to shortages, however - just a few weeks after Turkey agreed to
sell water to Israel, officials were warning of a water crisis.
Another project, a system of 22 dams on the Tigris and Euphrates rivers, has
provoked criticism from downstream neighbours Iraq and Syria.
China's urban community suffers most from
water scarcity. In 1990, about 26 percent of
the total population lived in cities, increasing
to 35 percent (or 450 million) 2000. Water
scarcity also remains a serious threat to the
nation's food self-sufficiency. About 70
percent of the grains produced in China are
cultivated on irrigated land. Food security is
expected to worsen with the expected
population rise from 1.2 billion to 1.5 billion in
2030.
National water use in China
Water consumption PRC: 550 billion m3 (2000)
Panting schemes to reduce soil erosion
(Mu Us desert northwestern of China)
South-to North water diversion project
Water scarcity
• Freshwater and the hydrological cycle
• Water “hot spots” in the world
• How to deal with water scarcity
– XXXX
– XXXX
• Global warming and water scarcity
VALUING WATER
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Dublin Statement on Water and Sustainable Development (1992):
'Principle No. 4: Water has an economic value in all its competing uses and should be recognized
as an economic good. Within this principle, it is vital to recognize first the basic right of all human
beings to have access to clean water and sanitation at an affordable price. Past failure to
recognize the economic value of water has led to wasteful and environmentally damaging uses of
the resource. Managing water as an economic good is an important way of achieving efficient and
equitable use, and of encouraging conservation and protection of water resources.‘
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Agenda 21, Chapter 18 (UNCED, 1992):
'Water should be regarded as a finite resource having an economic value with significant social
and economic implications regarding the importance of meeting basic needs.‘
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Ministerial Declaration of the 2nd World Water Forum (The Hague, 2000):
'To manage water in a way that reflects its economic, social, environmental and cultural values for
all its uses, and to move towards pricing water services to reflect the cost of their provision. This
approach should take account of the need for equity and the basic needs of the poor and the
vulnerable.‘
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Ministerial Declaration of the 3rd World Water Forum (Kyoto, 2003):
'Funds should be raised by adopting cost recovery approaches which suit local climatic,
environmental and social conditions and the "polluter-pays" principle, with due consideration to the
poor. All sources of financing, both public and private, national and international, must be
mobilized and used in the most efficient and effective way.'
Water pricing in developed
countries
When the supply systems are deficient, the poor are the first to suffer. Those who do not
benefit from a house connection are often forced to obtain water from informal street
vendors at a much higher price.
The table below shows house connection prices versus informal vendor prices (in US$) in
selected developing countries.
City
Cost of water for
domestic use
(a)(house
connection: 10
m3/month) in
US$/m3
Ratio (b/a)
Price charged by
informal vendors
(b) in US$/m3
Vientiane (Lao PDR)
0.11
14.68
135.92
Male* (Maldives)
5.70
14.44
2.53
Mandalay (Myanmar)
0.81
11.33
14.00
Faisalabad (Pakistan)
0.11
7.38
68.33
Bandung (Indonesia)
0.12
6.05
50.00
Delhi* (India)
0.01
4.89
489.00
Manila (Philippines)
0.11
4.74
42.32
Cebu (Philippines)
0.33
4.17
12.75
Davao* (Philippines)
0.19
3.79
19.95
Chonburi* (Thailand)
0.25
2.43
9.57
Phnom Penh
(Cambodia)
0.09
1.64
18.02
Bangkok* (Thailand)
0.16
1.62
10.00
Ulaanbaatar
(Mongolia)
0.04
1.51
35.12
Hanoi (Viet Nam)
0.11
1.44
13.33
Mumbai* (India)
0.03
1.12
40.00
Ho Chi Minh City (Viet
Nam)
0.12
1.08
9.23
Ecosystems value
The multiple roles of the aquatic ecosystems, called
ecosystems services, present an economic value to water.
Ecosystem type
Total value per
hectare (US$/year)
Total global flow
value (US$
billion/year)
Tidal marsh/mangrove
6,075
375
Swamps/floodplains
9,990
1,648
Lakes/rivers
19,580
3,231
Total
5,254
Global and per hectare values of ecosystems have been calculated based on the
estimation of the indirect values of the aquatic ecosystems in flood control, groundwater
recharge, shoreline stabilization and shore protection, nutrition cycling and retentions,
water purification, preservation of biodiversity, and recreation and tourism.
[Source]: extracted from the World Water Development Report. Costanza et al., 1997.
'The nature of the world's ecosystem services and natural capital' Nature, Vol. 387, pp.
253-60.
Water scarcity
• Freshwater and the hydrological cycle
• Water “hot spots” in the world
• How to deal with water scarcity
– Water pricing/valuation
– XXXX
• Global warming and water scarcity
Water use efficiency in
agriculture
Drip irrigation reduces water use
by 30 to 70 percent and increases
crop yield by 20 to 90 percent
compared with flooding methods
These field are watered by furrow
irrigation. Note the black gates that
control the entry of water from the
larger channel in front into the furrows.
High-pressure irrigation of
crops is more efficient than
furrow irrigation, but not as
efficient as low-pressure
irrigation.
Courtesy Dorchester County Cooperative Extension
Partial Root Drying technique
PRD used in grape, lychee- and
mangocultivations in Asia &
Australia
Seawater Desalination System
Membrane distillation uses a special
membrane to bring out the water vapor
generated from collected seawater,
collecting it as freshwater, and it is a
revolutionary new method different from its
predecessors. This special membrane is a
porous hydrophobic membrane, which
means that water vapor can pass through it,
but drops of water cannot. As shown in the
diagram, by passing hot seawater through
one side of the membrane, only the water
vapor generated from the seawater passes
through. The water vapor is then cooled by
the cool water on the other side of the
membrane, forming water drops, resulting in
freshwater.
Reducing urban water consumption
Can technology help?
Simple devices like low-flow toilets can cut usage by 70 percent. When New York City was faced with
spending $1 billion on a new pumping station in the early 1990s, it opted instead to replace toilets. By
1997, after the city spent $295 million on incentives, 1.33 million new toilets had been installed, saving 70
million to 90 million gallons per day. Overall, per capita consumption dropped from 195 gallons in 1991 to
169 gallons in 1999. ( 1 gallon = 4,55 l).
Water scarcity
• Freshwater and the hydrological cycle
• Water “hot spots” in the world
• How to deal with water scarcity
– Water pricing/valuation
– Water saving technologies
• Water & Conflict ?
Water & Conflict
• For assignment see Blackboard