Dammed to destruction
PHILIP B. WILLIAMS
says that the onslaught on fresh free-flowing
water
by the building of massive dams is the greatest
threat to the
world's rivers
The accelerating deterioration of the world's river ecosystems has been
largely ignored, while other global environmental problems, such as the
destruction of the world's forests and the depletion of ocean fisheries,
have been the subject of much concern and debate. But the declining health
of almost all the world's major river ecosystems is a key factor in many
of the most important symptoms of the global environmental crisis, from
the collapse of coastal fisheries to the spread of waterborne diseases;
from steadily worsening flood disasters to the deterioration in drinking
water supply; from eroding shorelines to the loss of wetlands; from the
extinction of river dolphins to the pollution of estuaries.
The integrity of our rivers has, indeed, been so neglected that we have
little data on the scale and speed of their deterioration. In 1992 the
United States National Academy of Sciences' report The Restoration of
Aquatic Ecosystems was unable to find any systematic analysis of the
extent of the destruction of river systems in the United States. The first
coherent survey of the global impact of human intervention was only
published in 1994. In a paper in Science that year, authors
Dynesius and Nilsson showed that 77 per cent of the large river systems in
the northern third of the world had been severely or moderately affected
by hydrologic alterations.
The impact of large dams
River ecosystems can be degraded by many human interventions, including
pollution, watershed destruction and channelization. But it is the impact
of large dams that is now having the most immediate and far reaching
effects. They cause huge changes in flows, transforming the character of
such major rivers as the Nile or the Indus.
Over the years, scientists have observed the impacts of dams and levees on
the ecology of rivers, riverbanks and estuaries. They have learned that
major alterations in flows affect most other aspects of the physical
system on which both wildlife and humans depend, including river
morphology, water quality, nutrient transport and estuarine hydrodynamics.
These changes also affect bank erosion, groundwater levels, shoreline
erosion, flood peaks, soil salinity and water temperature: the list of
known impacts multiplies with every year. Though dam building is an
ancient technique, it is only in the last 100 years - primarily in the
last 50 - that technology has enabled humanity to create the truly massive
structures that have such deadly impacts on our rivers. The first country
to embark on big dam building - and the first to experience the resulting
problems - was the United States: today it has few rivers left to dam. The
most publicized result of the love affair with big dams and associated
river works has been the drastic decline in salmon populations. River
engineering is also the main cause of destruction of the river ecosystems:
changes to the physical habitat, river channels and banks, for example,
are implicated in 93 per cent of freshwater fauna declines in North
America.
Projects like damming the Columbia, draining the Everglades and embanking
the Lower Mississippi were at best simplistic, flawed solutions. Their
economic costs, caused by environmental damage, were unforeseen or
discounted. Their economic benefits were realized only by a few at the
expense of the nation as a whole. Large-scale water projects have lost
much of their popular support because of their huge cost and the growing
realization of their escalating long-term ecological effects. Correcting
past mistakes is now the main activity of those responsible for America's
rivers: among current multi-million projects funded by the United States
taxpayer are the restoration of the Columbia River's salmon run, the
dechannelization of Florida's Kissimee River and the effort to find
non-structural ways of managing floods on the Mississippi.
These lessons have not yet been learned elsewhere in the world. Beguiled
by a false association between big water projects and economic
development, many developing countries continue to import obsolete river
engineering technology. The pace of construction of big dam projects
proceeds unabated even as the number of suitable sites diminishes. About
1,200 dams higher than 15 metres are started worldwide every year. Current
major river engineering projects planned or under construction include:
- A programme to build a staircase of six major hydroelectric dams on the
Mekong, a river whose biodiversity is considered second only to the Amazon
and whose fishery and floodplains support much of the population of
Cambodia.
- A plan to build a 3,400 kilometres shipping channel, the Hidrovia, up
the Paraguay and Parana Rivers into the 200,000 square kilometres
Pantanal, one of the world's largest tropical wetlands.
- The construction of the Three Gorges Dam, the world's largest hydro
project, across the Yangtze River, displacing more than 1.2 million people
and irrevocably changing the river system.
These projects, and many others, will have devastating long-term impacts
on river ecosystems - impacts with direct economic and social costs - but
proponents have ignored them or brushed them aside. An internal survey of
recent World Bank hydroelectric dam projects showed that 58 per cent were
planned and built without even the most rudimentary consideration of
downstream impacts - even when these could be predicted to cause massive
coast erosion and pollution. Within a few decades, if policies do not
change quickly, every major river system - including the Amur, the
Yangtze, the Mekong, the Salween and the Amazon - will be as degraded and
impoverished as the Colorado, the Nile, the Columbia, the Indus and the
Parana have become in the last 50 years.
Why does this onslaught on fresh, free-flowing water - one of the most
important processes supporting the global ecosystem - continue? The answer
is due, in large part, to the political dynamics created when
unaccountable development institutions promote and fund large
infrastructure projects as a sure fire way of achieving rapid economic
growth. This has been supported by a powerful international water project
construction lobby and has usually benefited economic and political elites
at the expense of rural populations. As understanding of the impacts of
human interventions on river systems broadens, and realization of the
long-term costs grows, the beneficiaries and promoters of large water
projects have an increasing interest in ignorance, deception and secrecy.
Ending secrecy, providing honest analysis of all future impacts, insisting
on open scientific review and making sure that affected communities have a
voice in decisions, are the keys to establishing sound decision-making
that protects river ecosystems.
People's livelihoods and culture depend, in much of the world, on
maintaining a healthy river ecosystem as a common resource. Fortunately
many have organized within the last decade to prevent the expropriation of
their rivers and the destruction of their way of life by dam projects.
People affected by projects in the Narmada Valley in India, in villages
along the Pak Mun River in Thailand, in the Mei Nung Valley in Taiwan,
along the San Francisco River in Brazil or in the long houses of the
Rajang River in Sarawak, have all become part of a coalescing
international movement. By stopping dams and water projects, these people
are having a greater effect in protecting global river ecosystems than
countless expert reports and prestigious United Nations conference
resolutions. In challenging the outmoded ideology of river engineering
development, the people of the valleys are leading the way for introducing
new ideas for managing their rivers that will preserve these ecosystems
for future generations.
Dr. Philip B. Williams is President of the International Rivers
Network.
