Perilous Times
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
* Adam Vaughan
*
guardian.co.uk, Wednesday 29 September 2010 17.53 BST
Chemical water pollution in China: Yangtze river, Anhui, China Chemical
waste water is discharged into the Yangtze river Photograph: Lu
Guang/Greenpeace
Nearly 80% of the world's rivers are so badly affected by humanity's
footprint that the water security of almost 5 billion people, and the
survival of thousands of aquatic species, are threatened, scientists
warned today.
The global study put together by institutions across the globe is the
first to simultaneously look at all types of human intervention – from
dams and reservoirs to irrigation and pollution – on freshwater. 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 said they 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," says Prof Peter
McIntyre, one of the lead authors, who began work on 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, including the Mississippi
river.
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 for waterways, 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.
Published in the journal Nature today, the international team behind
the report looked at 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,
the map shows. 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 extracting water for
irrigation.
Even the Amazon, which is 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 hopes the report highlights 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 the UK, rivers have been getting cleaner over the past decade. But a
report by the UK's Environment Agency last year admitted only five of
6,114 rivers in England and Wales are considered pristine and
three-quarters were so polluted they are likely to fail new European
quality standards.