Posted on 18 April 2011
- Phnom Penh, Cambodia: A new study by WWF
on aquatic ecosystem connectivity reveals
that the Mekong region could have equivalent
power but dramatically less damage to river
functioning by opting for tributary rather
than main channel dams.
Poorly evaluated and
uncontrolled dam development could also
take the Mekong to a tipping point past
which vital natural processes, such as sediment-
and nutrient transport and fish migration,
could no longer be taken for granted, WWF
warned.
“No part of the Mekong
River still provides connectivity to all
the 13 ecosystem types classified by a recent
WWF study,” said Nikolai Sindorf from WWF
Conservation Science Program. “The impact
of continuing incremental dam development
will disconnect more-and-more ecosystem
processes.”
“Where it gets alarming
is the disproportional amount of negative
impact from dam construction on the lower
mainstream of the river such as Xayaburi,
a dam proposed in northern Laos. The Mekong
is extremely sensitive to the impacts of
mainstream dams because of its layout -
a very long mainstream fed by relatively
short tributaries.“
Xayaburi, the first
of 11 dams proposed for the Mekong stream,
is projected to produce 1260 MW of power
while reducing the basin’s total connectivity
by five percent. In contrast the 1070MW
Nam Theun 2 dam on the Nam Theun River in
Laos took only 0.8 per cent out of the Mekong’s
connectivity, and the 1540MW Se San cascade
of 6 dams decreased connectivity by just
1.2 per cent.
The proposed Xayaburi
dam would cut 9 aquatic ecosystems upstream
out of a total of 13 using WWF’s classification.
Meanwhile, both Nam Theun 2 and the Se San
cascade only block a single ecosystem in
much smaller parts of the basin.
Ecosystem connectivity
is critical to maintain the river and its
reproductive processes. The study shows
graphically that the 50 larger dams located
on tributaries already cause serious interruptions
to relevant river processes. In the new
study, which quantifies the fragmentation
by cumulative dam development on the Mekong
river system by WWF scientists, “ecosystem
connectivity” was measured by the overlap
of those ecosystem processes vital to river
functioning under an array of conditions
such as land cover, hydrology and seasonal
factors.
“The impact of basin-wide
dam planning on ecosystem connectivity needs
to become one of the measures against which
projects are assessed,” said Dang Thuy Trang,
Manager, Sustainable Hydropower and River
Basin Programme, WWF Greater Mekong Programme.
“This will make it easier to develop the
Mekong basin with a much lower environmental
footprint. Ultimately, this would lead us
to a situation where local energy demands
are met, and relevant ecosystem processes
are conserved basin-wide.
WWF is calling for a
10-year delay in the approval of the mainstream
dams to fully consider the costs and benefits
of their construction and operation. Immediate
energy needs can be met from multiple hydropower
projects on some selected Mekong tributaries
where connectivity impacts are disproportionally
lower.
+ More
Deferral of Mekong dam
to ministerial level signals recognition
of potential negative impacts
Posted on 19 April 2011
- Vientiane, Laos: The intergovernmental
panel of the Mekong River Commission (MRC)
has deferred the final decision on the construction
of the Xayaburi dam in Laos to the ministerial
level, following concerns raised by Cambodia,
Thailand and Vietnam.
The decision comes amidst
the submission of a growing body of evidence
to the Commission highlighting risks to
biodiversity, fisheries and livelihoods
of millions of people in the Mekong River
Basin. Particularly vulnerable areas include
fisheries and the Mekong Delta.
A WWF-commissioned review
of the Xayaburi project found that the Environmental
Impact Assessment (EIA) and Feasibility
Study (FS) for the proposed dam were woefully
inadequate and fell well below international
standards for such studies. Changes in flows,
sediment and nutrients are some of the areas
that require further analysis, says WWF.
“Any decision made will
have implications for generations to come,”
says Dr Jian-hua Meng, WWF International
Sustainable Hydropower Specialist. “It is
clear that the governments of Cambodia,
Thailand and Vietnam are acknowledging the
gaps in knowledge of the expected impacts
from the dam.”
An experts meeting held
in Vientiane in 2008 to review the impact
of mainstream dams on fish migration concluded
that existing mitigation technology used
for salmon species in Europe and North America
cannot handle the scale of fish diversity
and migration in the Mekong mainstream.
WWF believes that the Mekong should not
be used as a test case for proving or improving
fish passage technologies.
WWF supports a 10-year
delay in the approval of lower Mekong mainstream
dams, including the Xayaburi hydropower
dam, to ensure a comprehensive understanding
of all the impacts of their construction
and operation, while immediate energy needs
are met with less challenging projects applying
state of the art sustainable hydropower
solutions are fast tracked on selected tributaries.
“The MRC has taken an
important step towards responsible decision-making
and is clearly looking at the potential
impacts the Xayaburi dam would have on millions
of people in the Mekong River Basin,” Dr.
Meng said. “Laos needs to build on the knowledge
gained in developing sustainable hydropower
in the region and follow examples such as
the Nam Theun 2 dam.”
