"Threats to human water
security and biological diversity are pandemic," Charles Vorosmarty of the
City University of New York, co-lead author of the report in the journal
Nature, told Reuters.
The international team of
scientists estimated that almost 80 percent of the world's population — or
about 5 billion people — lived in areas with high levels of threat to water
security, caused mainly by river mismanagement and pollution.
"Rivers in Crisis,"
Nature said on its front cover.
A map showed high levels of
threat, in red, for much of the United States including the Mississippi Basin,
along with almost all of Europe. India, including the Ganges Basin, and eastern
China with the Yangtze River were also shown in red.
Rising wealth often meant
worsening threats, for instance from badly sited dams or rising pollution from
fertilizers, pesticides and other chemicals. Rich nations then covered up
mismanagement by installing costly treatment plants.
The authors urged a re-think
to safeguard rivers, especially those now less affected in developing nations.
The world population is on track to reach 9 billion by 2050 from 6.8 billion
now.
The study said it was first
to examine in detail a twin set of threats — to clean water supplies for people
and to the biological diversity of life in rivers, from fish to crocodiles.
"Given escalating trends
in species extinction, human population, climate change, water use and
development pressures, freshwater systems will remain under threat well into
the future," they wrote.
Least affected rivers were in
parts of Siberia, Canada, Alaska, the Amazon Basin or northern Australia, they
said. Parts of the Amazon, the Congo and the Nile had low threats.
In rich nations, people often
failed to grasp the underlying problems with water supplies because tap water
was cleaned. "In the industrialized world, the water management strategy
is to patch up the problems at the end of the pipeline rather than the underlying
causes," Peter McIntyre, co-lead author at the University of Michigan,
told Reuters.
The study urged other nations
not to follow the rich which had invested trillions of dollars in managing
rivers, ranging from dams for hydro-electric plants to building artificial
barriers to allow cropland on flood plains.
"If your concern is
flooding you might wish to preserve flood plains and wetlands in low-lying
areas as they absorb the shock of floods," Vorosmarty said.
"That would obviate the
need to build a flood containment system costing millions of dollars," he
said.
In one positive example, New
York City bought an area of the Catskills Mountains to help provide naturally
filtered water, reckoning it cheaper than a water treatment plant.

The
authors said that it might take decades to get politicians sufficiently engaged
to fix the problems. "In the meantime, a substantial fraction of the
world's population and countless freshwater species remain imperiled,"
they wrote.