New Internationalist Issue 273
Rivers - The Facts
For centuries the great river systems of the South have watered the fields, put fish on the table and acted as avenues of communication with the outside world. Their importance gives them a crucial place in the cosmology of myth and religion. But now rampant industrialism has brought competing demands that threaten both traditional ways of life and the river eco-systems themselves.
The Nile
Eco-system:
The longest river in the world. The Blue Nile rises in the Ethiopian highlands
and the White Nile flows out of Lake Victoria through the tropical plains of
Southern Sudan and the great Sudd swamps. They join together just north of the
Sudanese capital of Khartoum and their combined flow survives the arid journey
through the Nubian and Arabian deserts to the Mediterranean. Almost all Egyptians
live clustered close to the Nile's banks.
Threats:
The Aswan High Dam - one of the world's largest - has proved a mixed blessing.
One gallon in five of the Nile's water evaporates from Lake Nasser behind the
dam. Lack of silt and improper drainage in downstream fields means serious problems
with water-logging and salination. Dependable water supplies mean new agricultural
production but often for thirsty export crops like cotton. Sea erosion and lack
of silt have reduced the Nile's fertile delta and the river is now a mere trickle
at its mouth.
The Amazon
Eco-system:
The largest river in the world in volume of water and drainage area and
one of the world's widest, varying between 6 and 10 kms. Originating in Peru,
it carries 1,000 million tons of sediment a year into the Atlantic Ocean in
Brazil and the patch of brown at its mouth can be seen darkening the South Atlantic
in satellite photos. Vast reaches of the Amazon basin are still essentially
unmapped and little-known.
Threats:
Massive logging campaigns have dramatically increased erosion and caused
international concern that rainforest destruction will contribute to ozone depletion
and global warming. While the slow-flowing Amazon has been saved from dam construction,
Brazil's official 'Plan 2010' envisages 80 dams on its tributaries. Dams like
the Balbina on the Vartna are flooding arable lands, uprooting inhabitants and
adding to rainforest destruction. Watershed stability is threatened by clear-cutting
for cattle rearing. 4
The Yangtze
Eco-system:
Known as the 'Long River' or 'The River of Golden Sand', the Yangtze is
the longest river in Asia. It rises in the Tanglha mountains very near Tibet
and flows through Szechwan and Hunan to enter the Yellow Sea near Shanghai.
Some of its 600 million annual tons of mud and silt gets deposited on its fertile
delta and Chongming Island at the river's mouth. The Yangtze has 700 tributaries
and its drainage basin covers 20% of China's total land area.6
One in 13 people on the planet live in its basin.
Threats:
The Yangtze's dangerous floods have drowned 300,000 people this century
alone. For centuries a system of dikes held back floods - some as ancient as
the eighth century are still in working order. The Three Gorges Dam will be
the world's biggest and is projected to control flooding and provide energy-inefficient
Chinese factories with hydro-power. It will cost $20 billion, take 20 years
to build and flood a million people from their homes. Some 300,000 farmers will
lose their land and controversies rage on the dam's effectiveness in controlling
floods and long-term social and ecological costs.
The Ganges
Eco-system:
The Ganges rises in the Himalayan glaciers in the mountainous region of
the north Indian state of Uttar Pradesh. It flows 2,480 kms through India to
enter the Bay of Bengal where it forms one of the world's largest deltas made
up of Bangladesh and the Indian state of West Bengal. The width of its flood
plain varies between two and eight kms.5
Threats:
The waters of the Ganges are considered sacred in Hindu mythology, but are
nonetheless heavily polluted, partly from the 40,000 people cremated yearly
at Benares, but mainly from the distilleries, refineries, chemical factories
and fertilizer complexes along the banks, especially at the city of Kanpur.
Earthquake danger due to over-damming endangers over 100 villages and the town
of Hardwar.5 Large-scale irrigation projects
started a century ago and 500 new ones in the last 40 years have displaced millions
of poor farmers and altered the volume speed and silt load of the river's flow.
The Zaire
(Congo)
Eco-system:
The source of the Zaire (meaning river) is the Lualaba river which rises
in the Zairian province of Katanga near the Zambian border. It heads north,
then west, then south swallowing river after river in its rush to discharge
1.4 million cubic feet per second into the Atlantic Ocean. The banks of the
Zaire are heavily forested and its relatively slow and navigable course is punctuated
by wild rapids at the Porte d'Enfer and the Stanley and Inga Falls.6
The Zaire has long been an African trade and communications route, home
to several pre-colonial kingdoms like the Luba inland and the Kongo near the
coast.
Threats: Despite the Inga dam and power site and some localized
pollution the Zaire is largely unaffected by industry. Overfishing is a potential
problem. But blueprints to divert a massive amount of flow north into the Sahel
to solve drought problems there have the support of Zaire's President Mobutu.
This would be one of the largest-ever water diversions - in one version carrying
100 cubic kilometres of water annually (more than the flow of the Nile). The
developmental and ecological problems of cutting the Zaire's flow and transporting
the fish, insects and diseases of tropical rainforest into a semi-arid desert
are unimaginable.
Down the Drain
Global water use has tripled since
1950 to 4,340 cubic kms - 8 times the annual flow of the Mississippi. Some 65%
of this is used in agriculture.
More than 10% of the world's
irrigated land suffers from yield-suppressing salt build-up which is spreading
at the rate of 1.5 million hectares a year. Currently less than 40% of water
used in irrigation ends up benefiting crops.3
Engineers have now built
36,000 dams worldwide. Construction continues at the rate of 170 dams a year.
An estimated 1% of dam capacity is lost every year as reservoirs become clogged
with a million tons of silt (about 10% of global river discharge). This fertile
silt is also lost to downstream farmers.4
Farmers could cut water
use by 10-50%, industry by 40-90% and cities by 1/3 with no sacrifice to economic
output or quality of life.3
1 Times Atlas of the World (1985).
2 Encarta '95 (Microsoft).
3 Last Oasis Sandra Postel (WW Norton, New York 1992).
4 The Dammed Fred Pearce (Bodley Head, London 1992).
5 The Ganges: Great Rivers of the World George F Mobley (National
Geographic 1984).
6 Encyclopaedia of the World's Great Rivers (Rand-Macnally, New
York, 1980).
©Copyright: New Internationalist 1995
