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From: Tsegai Emmanuel (emmanuelt40@gmail.com)
Date: Thu Sep 30 2010 - 00:30:39 EDT
Human Impact on World's Rivers 'Threatens Water Security of 5 Billion' Study
on effect of all human intervention on water supplies finds water security
and biodiversity severely damaged
by Adam Vaughan
The world's rivers are so badly affected by human activity that the
water<http://www.guardian.co.uk/environment/water>security of almost 5
billion people, and the survival of thousands of
aquatic species, are threatened, scientists warned .
The study <http://riverthreat.net/>, conducted by institutions across the
globe, is the first to simultaneously look at all types of human
intervention on freshwater – from dams and reservoirs to irrigation and
pollution <http://www.guardian.co.uk/environment/pollution>. It paints a
devastating picture of a world whose rivers are in serious decline.
While developing countries are suffering from threats to both water security
and biodiversity, particularly in Africa and central Asia, the authors were
surprised by the level of threat posed to wildlife in rich countries.
"What made our jaws drop is that some of the highest threat levels in the
world are in the United States and Europe," said Prof Peter McIntyre, one of
the lead authors, who began the project as a Smith Fellow at the University
of Michigan.
"Americans tend to think water pollution problems are pretty well under
control, but we still face enormous challenges."
Some of the worst threats to aquatic species in the US are in the
south-eastern states. Prof Charles Vörösmarty of the City University of New
York, lead author and an expert on global water, said the impact on wildlife
in developed countries was the result of river systems that had been heavily
engineered and altered by man. "With all the protection the EU has in place,
it was surprising to see it was a hotspot for biodiversity loss. But for a
long time Europeans have altered their landscapes, including the removal of
90% of wetlands and floodplains, which are crucial parts of river
ecosystems," he said.
The team behind the report, published in the journal Nature, examined
datasets to produce a map of how 23 different human influences – such as
dams, the introduction of alien non-native fish, and pollution – affect
water security and biodiversity. Previous studies have tended to look at
just one influence at a time.
Even the world's great rivers, such as the Yangtze, the Nile and the Ganges,
are suffering serious biodiversity and water security stress.
Despite their size, more than 30 of the 47 largest rivers showed at least
moderate threats to water security, due to a range of human impacts such as
pollution and irrigation. Even the Amazon, considered to be relatively
pristine, still has human fingerprints on it, said Vörösmarty.
"While the Amazon is in generally good shape, in the upstream regions, such
as Peru, there are many high density areas of people that inject threat into
the system.
"The legacy of that human threat passes downstream into the remote forested
areas of the river."
Globally between 10,000 and 20,000 aquatic wildlife species are at risk or
face extinction because of the human degradation of global rivers, the
report said. The world's least affected rivers, the authors found, were
those furthest from populated areas, such as remote parts of the tropics,
Siberia and elsewhere in the polar regions.
Vörösmarty said he hoped the global report would highlight the need to
address the root causes of the degradation of rivers. "We're spending
trillions of US dollars to fix a problem we've created in the first place.
It's much cheaper to treat the causes rather than the symptoms, which is
what we do in the developed world today," he said.
In Britain rivers have been getting cleaner over the past decade. But a report
by the UK's Environment Agency last year
admitted<http://www.guardian.co.uk/environment/2009/sep/22/pollution-rivers-environment-agency-england>only
five of 6,114 rivers in England and Wales were considered pristine and
three-quarters were likely to fail new European quality standards for
various reasons.