Rivers must flow: The case against big dams
Large dams threaten the planet's riverine lifelines and action must be
10 Jan 2012
By Lori Pottinger
Berkeley, CA - Rivers act as the planet's circulatory system. Like our
body's circulation system, the planetary one doesn't work very well
when it's clogged. If a river's flow is its heartbeat, then we humans
are the heart disease. We've blocked most major rivers with dams, bled
them dry with water diversions, and given up all too many once-great
rivers for dead once we've used them up.
More than 50,000 large dams now choke about two-thirds of the world's
largest rivers. The consequences of this massive engineering programme
have been devastating. Large dams have wiped out species; flooded huge
areas of wetlands, forests and farmlands; displaced tens of millions
of people, and affected close to half a billion people living
Large dams hold back not just water, but silt and nutrients that
replenish farmlands and build protective wetlands and beaches. Dams
change the very riverness of our waterways, in ways we can't always
see, but that the earth can certainly feel.
US dam removed to check salmon decline
Of all the complex and interconnected environmental disruptions that
dams inflict on the landscape, the most obvious is the permanent
inundation of forests, wetlands and wildlife. Reservoirs have flooded
vast areas - at last count, the world's dams had flooded an area
bigger than the United Kingdom.
Equally important is the quality of these lost lands: river and
floodplain habitats are some of the world's most diverse ecosystems.
Plants and animals that are closely adapted to valley habitats often
cannot survive along the edge of a reservoir.
Dams also are usually built in remote areas that are the last refuge
for species displaced by development elsewhere. In large measure due
to dams, freshwater ecosystems are losing species and habitats faster
than any other type of ecosystem.
Large dams also fragment the riverine ecosystem, isolating populations
of species living up and downstream of the dam and cutting off
migrations and other movements. Because almost all dams reduce normal
flooding, they also fragment ecosystems by isolating the river from
its floodplain. The elimination of the benefits provided by natural
flooding may be the single most ecologically damaging impact of a dam.
Rivers that capture carbon
A newly significant environmental impact of dams is how they might
eliminate a source of carbon capture in some watersheds. Scientists
have discovered that major rivers play a surprisingly large role in
helping tropical oceans absorb carbon.
The vast flow of major river basins delivers phosphorus, iron and
other nutrients far offshore, where it is consumed by certain forms of
sea life such as phytoplankton. These microorganisms "fix" carbon by
taking it out of the atmosphere. The organisms eventually sink, taking
carbon with them to the deep seafloor. Dams could change the delicate
workings of this ecosystem service by holding back the river-borne
sediment that feeds this cycle.
At least two major river basins slated for damming - the Amazon and
the Congo - are important planetary sources of nutrient flows. A 2009
study of Africa's biggest proposed hydropower project, the Grand Inga
Complex on the Congo, says that "plans to divert, store or otherwise
intervene in Lower Congo River dynamics are truly alarming" and
"ignore the river's significant influence on the equatorial Atlantic,
which, in turn, is central to many climate change models".
Scientists predict that damming the Amazon, the Congo, the Mekong and
other high flow rivers in warm ocean areas could reduce their ability
to mitigate climate change. Research on other rivers' carbon-sink
capacity is underway.
What can be done?
"Free-flowing rivers are now such a rarity that they would be
classified as an endangered species if they were considered living
things rather than merely the support systems for all living things."
- Lori Pottinger
Free-flowing rivers are now such a rarity that they would be
classified as an endangered species if they were considered living
things rather than merely the support systems for all living things.
Yet we can take small comfort from the fact that rivers have a natural
ability to self-heal.
Over time, all of the efforts to engineer dynamic, powerful and
unpredictable rivers will inevitably fail, and the river will have a
chance to restore itself. As renowned river explorer Richard Bangs
wrote in his book River Gods, "Wild rivers are earth's renegades,
defying gravity, dancing to their own tunes, resisting the authority
of humans, always chipping away, and eventually always winning." We
all win when rivers are allowed to flow freely.
But we can't just wait for rivers to chip away at the dams that clog
them. First, we need to protect remaining free-flowing rivers while we
still have some to protect. A growing movement of citizen activists in
countries where damming is on the rise is working to get governments
to pass laws that would protect free-flowing rivers. A number of
countries have devised legislative tools that are useful models for
such efforts; the US Wild and Scenic Rivers Act is just one effective
Where entire rivers cannot be protected, we must prioritise the
protection of areas of great ecological integrity. This "landscape
approach" requires that a network of regional-scale ecosystems be
protected; that sufficient levels of each ecosystem are included to
make protected areas ecologically viable and to maintain the integrity
of populations, species and communities, and that the protected areas
encompass variability of habitat within ecosystems.
The biggest challenge is not the science of evaluating what to save,
but generating the political will needed to maintain the protections.
When rivers are dammed, we must insist on naturalistic flows to
support the basic ecosystem functions of dammed rivers. So-called
"environmental flows" are planned releases intended to support the
basic ecosystem functions of dammed rivers. Such systems can be
complex to devise and maintain, and many dams around the world
currently lack the mechanisms needed to control water discharge.
Therefore, as with medicine, the best approach is to "first, do no
harm" - no dams unless there are no better options (and there almost
But once a dam is inevitable, it is imperative that the river be
maintained with as natural a flow as possible. As water expert Sandra
Postel has written, "an ethic of stewardship toward fresh water and
its dependent species requires that we err on the side of allocating
too much water to ecosystems rather than too little."
And finally, we must remove the worst dams to restore flows that
support habitats, fisheries and other natural services lost to poorly
planned dams. A growing movement to remove dams and restore rivers in
the United States is a global inspiration. American Rivers estimates
that more than 925 dams have been removed over the past 100 years in
We must also undertake a greater study of the world's river-dependent
biodiversity, much of which still remains unknown to us. As Pulitzer-
prize-winning biologist EO Wilson has said:
In reality, we don't know 90 per cent of what we're losing,
because we've only discovered about ten per cent of the planet's
species. When we're trying to stabilise the environment - trying to
stop ecosystems from collapsing in the face of global warming or big
dams or whatever - we really need to know what's in each of these
habitats. We need then to move ecology way ahead of where it is today,
really make it a much bigger priority.
Chileans mobilise against proposed dam
Because most new dams are being built in the global south, we must
move more quickly to help the developing world adopt clean energy and
water supply systems that preserve riverine lifelines. Large dams are
an ineffective approach for solving the water and energy needs of the
poor majority. Small projects take less time to build, are more easily
phased, and are more adaptable to a changing climate.
Breakthroughs in clean energy technologies and water-efficiency
methods are not only better suited to strengthen energy and water
access for the poor, they will also strengthen our resilience to
climate change. They do, however, require greater investment in
research, development and deployment.
The world's wealthiest countries should assist the world's poorest in
developing a cleaner, more efficient energy path and water-secure
future rather than in destructive mega-projects that repeat the
mistakes of the past.
The final piece of the puzzle is personal. Protecting our rivers now
is the health insurance policy we all need for a climate-challenged
future. Finding ways to become an advocate for a river near you in
2012 would be a good way to celebrate the new year.
Lori Pottinger has worked for the California-based International
Rivers for 17 years. She works on African river issues, and is the
editor of the group's magazine, World Rivers Review.
The views expressed in this article are the author's own and do not
necessarily reflect Al Jazeera's editorial policy.
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