Transcript Slide 1

http://news.bbc.co.uk/1/hi/sci/tech/5269296.
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Physical water scarcity: More than 75% of river flows are allocated to
agriculture, industries or domestic purposes (accounting for recycling of
return flows). This definition of scarcity - relating water availability to water
demand - implies that dry areas are not necessarily water-scarce, eg
Mauritania.
Approaching physical water scarcity: More than 60% of river flows are
allocated. These basins will experience physical water scarcity in the near
future.
Economic water scarcity: Water resources are abundant relative to water
use, with less than 25% of water from rivers withdrawn for human
purposes, but malnutrition exists. These areas could benefit by
development of additional blue and green water, but human and financial
capacity are limiting.
Little or no water scarcity: Abundant water resources relative to use. Less
than 25% of water from rivers is withdrawn for human purposes.
Desalination
Ogallala Aquifer, SW USA
Ninety-five percent of the United States' fresh water is
underground. One crucial source is a huge underground
reservoir, the 800-mile Ogallala aquifer which stretches from
Texas to South Dakota and waters one fifth of US irrigated
land. The aquifer was formed over millions of years, but has
since been cut off from its original natural sources. It is being
depleted at a rate of 12 billion cubic metres a year –
amounting to a total depletion to date of a volume equal to
the annual flow of 18 Colorado Rivers. Some estimates say it
will dry up in as little as 25 years.
Many farmers in the Texan High Plains, which rely particularly
on the underground source, are now turning away from
irrigated agriculture as they become aware of the hazards of
overpumping.
Mexico City
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.
Spain
A plan to alleviate persistent drought problems along Spain's
parched southern coast has sparked controversy. Tens of
thousands protested in 2002 against the Government's 4.2
billion euro proposal to channel water from the River Ebro to
provide much needed supplies for tourism and agriculture in
Valencia, Almeria and Murcia.
As well as creating conflict between regions, the plan has
drawn criticism from environmentalists. They say the Ebro's
levels are already dropping, loss of silt would damage wetlands
at the river's mouth, and the country should be trying to
conserve water rather than undertaking large infrastructural
projects anyway.
The argument over the idea has raged for 15 years and
continues despite alterations to the plan to reduce its
environmental impact.
Aral Sea, Uzbekistan
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.
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.
Turkey has spent billions of dollars in the past decades building
dams to increase its water reserves and boost its hydroelectric
capabilities. But a number of projects, particularly the Ilisu and
Yusefeli dams, have faced delays after several Western
companies withdrew funding following bad publicity over
human rights concerns.
Another project, a system of 22 dams on the Tigris and
Euphrates rivers, has provoked criticism from downstream
neighbours Iraq and Syria.
Israel & The West Bank
With 5% of the world's population trying to survive on 1% of its water, there
is strong competition for water in the Middle East A series of dry years together with population growth - has recently increased the pressure. Both
Israel and Jordan rely on the River Jordan – but Israel controls it and has cut
supplies during times of scarcity.
The level of the Sea of Galilee has dropped in recent years, sparking fears
that Israel's main reservoir will become salinated.
The Palestinians - whose water supply is also controlled by Israel - say
supplies are intermittent and expensive, and that the underground aquifer
which they share with Israel has become depleted and damaged through
overuse. Israelis in the West Bank use four times as much water as their
Palestinian neighbours.
On its northern border, Israel threatened military action in 2002 when
Lebanon opened a new pumping station taking water from a river feeding
the Jordan.
To help ease the crisis, Israel has agreed to buy water from Turkey and is
investigating building desalination plants.
Chad
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.
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 7,000km-long 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.
Iraq
Government drainage and irrigation schemes in southern
Iraq have led to the loss of at least 90% of one of the world's
most significant wetlands. A vast network of canals has
diverted water from the 20,000 square kilometres of marsh
land between the Tigris and Euphrates, in places leaving
nothing but salty, crusted earth behind.
Turkish dams upstream are also thought to have reduced the
water flow and contributed to the wetlands' fate.
Scientists fear the marshes, the habitat of 14 globally
threatened species and traditional home of Iraq's Marsh
Arabs, may disappear completely within three to five years.
Most of the Marsh Arabs have fled, facing both political
persecution under Saddam Hussein's regime and the loss of
the freshwater which sustained their way of life.
China
China is undertaking two huge projects to tackle flooding in the south and
drought in the north. The Three Gorges Dam under construction on the
Yangtze River aims to control flood waters and generate power. But the
project – the largest of its kind in the world - has been dogged by corruption
scandals and criticised for its impact on the environment and the million
people who have been uprooted.
In the north, all three rivers feeding China's Northern Plain are severely
polluted, damaging health and limiting irrigation.
The lower reaches of the Yellow river, which feeds China's most important
farming region, ran dry for 226 days in 1997. Between 1991 and 1996, the
water table beneath the north China plain fell by an average of 1.5 metres a
year.
To combat this, work has begun on China's biggest ever construction project
- a massive scheme to channel billions of cubic metres of water from the
Yangtze to the replenish the dwindling Yellow river.
River Ganges
The most sacred Hindu river, the Ganges, is suffering from depletion, pollution
and has been the source of a long-running dispute between India and
Bangladesh. The glacier which feeds it is retreating hundreds of feet each year
- experts blame climate change.
Deforestation in the Himalayas has caused subsoil streams flowing into the
river to dry up.
Downstream, India controls the flow to Bangladesh with the Farakka Barrage,
10km on the Indian side of the border. Until the late 1990s, India used the
barrage to divert the river to Calcutta to stop the city's port drying up during
the dry season. This denied Bangladeshi farmers water and silt, and left the
Sundarban wetlands and mangrove forests at the river's delta seriously
threatened.
The two countries have now signed an agreement to share the water more
equally. Water quality, however, remains a huge problem, with high levels of
arsenic and untreated sewage in the river water.
Southern Australia
Australia is the continent with the least rainfall, apart from Antarctica. Its
two largest rivers, the Murray and the Darling, have been extensively
dammed for power and irrigation, reducing flows to the sea by threequarters – but providing three million people and 40% of Australia's farms
with water. Salt rising to the surface as the lower reaches of the Murray
dried out has destroyed prime agricultural land. Wetlands have shrunk,
species numbers have dropped and the Australian National Trust has
declared the whole river an "endangered area".
In the east, the Snowy River was dammed and diverted to the Murray
basin decades ago to water the country's dry interior. But the ecological
impact on the depleted river was so great that some flow was restored in
2002.
Water extraction from the Murray river was capped in 1995 and
programmes to repair some of the destruction are now under way.