Tuesday, September 20, 2011

World's Dams Unprepared for Climate Change Conditions

Climatewire | Energy & Sustainability
World's Dams Unprepared for Climate Change Conditions

Dams have been designed for river flows that will soon no longer apply,
according to new research
By Julia Pyper and ClimateWire | September 16, 2011
Scientific American

DAM PROBLEM: The world's dams are being built for water flow conditions
that may no longer apply thanks to climate change, according to new

Over the past four years, John Matthews has been traveling the world to
better understand freshwater and climate change issues. He found that
poor planning is creating one of the biggest water-related threats.

"We need to think about managing water in a much more flexible way,"
said Matthews, who is director of fresh water and adaptation at
Conservation International. "Let's not just design for a single future;
let's think about multiple possible futures."

In a paper published this month in the journal PLoS Biology, Matthews
and his co-authors argue that investment and management decisions risk
exacerbating climate-initiated changes, which could lead to economic

The conventional method of building dams is fundamentally flawed, said
Matthews. Looking at the available data, engineers decide on a flow rate
that they feel will optimize the infrastructure project. The problem,
says Matthews, is that historical data is not a very good guide to the
future of freshwater resources -- particularly now that extreme water
conditions have been exacerbated by a rapidly changing climate.

According to the United Nations, humans will feel the effects of climate
change through the water supply. The hydrological cycle -- which
includes surface and ground sources, glaciers, precipitation, runoff and
vaporization --- is very sensitive to small climatic shifts. This is a
concern not only because water is essential for subsistence, but because
it's also the key to economic development. The way humans are managing
water infrastructure and conservation, the authors argue, is only
intensifying these issues.

Old dams, new realities
"It's not that we need to give up designing; it's that we need a better
design and decisionmaking process," said Matthews. "We need to think
carefully about how conditions may be shifting, because there are some
things that we can say with high confidence are happening because of
climate change."

Over the past century, dams made in the West have become more mismatched
with their ambient climate. The Hoover Dam​, for instance, was designed
based on a 30-year period that had markedly higher precipitation levels
than today. As a result of a decade of drought, the dam is now operating
at only 30 percent of its capacity, said Matthews, and new mechanisms
have been added to cope with the lower water levels.

When infrastructure plans are based on a set climate scenario, rather
than a flexible one, it can be very costly in both human and economic
terms, especially in the developing world, the paper argues.

Less-developed areas, particularly parts of East and South Asia, are now
entering a period of rapid hydro infrastructure development. Since water
managers are largely following the West's rigid planning model, these
countries are going to have difficulty adapting to changes in water

According to the Organisation for Economic Co-operation and Development,
40 percent of all development investments are at risk due to climate
change, write authors in the PLoS paper. If a hydropower project fails
to fulfill expectations due to the effects of climate change,
governments could struggle to pay back loans from development investors.

New dams and power shortfalls
Masses of people could also face prolonged brownouts. Matthews saw this
take place in Nepal, where low water levels rendered a brand-new dam
project ineffective and cut off the water supply farther downstream.

"[Developing countries] are likely to make themselves poorer and make
species and ecosystems decline at the same time, and I think that's a
huge crisis," said Matthews.

The solution is to build new water infrastructure in stages, say the
authors of the PLoS paper. Using that approach, managers can adjust
their strategy as climate patterns become clearer. Another step is to
integrate ecosystems into infrastructure development -- by "building
with nature" rather than on top of it, using a system that will be more

Finally, it's necessary to plan for multiple future climate scenarios by
coordinating engineers, economists and conservationists. A collective
approach will result in a more robust long-term strategy.

If water management practices stay the same and do not account for
future risks, then "we're building things based on a hydrological lie,"
said Matthews.

Reprinted from Climatewire with permission from Environment & Energy
Publishing, LLC. www.eenews.net, 202-628-6500

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