do massive dams ever make sense

8/12/2019 Do Massive Dams Ever Make Sense

http://slidepdf.com/reader/full/do-massive-dams-ever-make-sense 1/6

MAGAZINE

Do massive dams ever make sense?

By Lauren Everitt San Francisco

1 March 2014

The Hoover dam

A new report from researchers at Oxford University argues that large dams are a riskyinvestment - soaring past projected budgets, drowning emerging economies in debt and failingto deliver promised benefits. Do they ever really make sense?

A peek over the edge of the Hoover Dam's 60-storey wall is enough to send shivers downanyone's spine. Constructed from enough concrete to pave a motorway from New York to San

http://www.bbc.co.uk/news/

http://www.bbc.co.uk/news/



Francisco - this colossal barrier is touted as a symbol of man's mastery over nature and amarvel of 20th Century engineering.

The dam was credited with helping jump-start America's economy after the Great Depression,reining in the flood-prone Colorado River and generating cheap hydroelectric power for aridsouth-western states. Even more miraculously, the Hoover Dam was completed two years

ahead of schedule and roughly $15m (£9m) under budget.But for megadam critics, the Hoover Dam is an anomaly. The Oxford researchers reviewed245 large dams - those with a wall height over 15m (49ft) - built between 1934 and 2007. Theyfound that the dams ran 96% over their approved budgets on average - Brazil's Itaipu damsuffered a 240% overrun - and took an average of 8.2 years to build.

In the vast majority of cases, they say, megadams are not economically viable.

But after a two-decade lull, large dams are once again being trumpeted as a ticket toprosperity. Countries from China to Brazil, via Pakistan and Ethiopia, are rushing to erect them.

With world electricity consumption expected to grow by more than 56% between 2010 and2040, according to the 2013 International Energy Outlook report, hydropower is a temptingoption.

More than 90% of the world's renewable electricity comes from dams, according to theInternational Commission on Large Dams.

Flooded vegetation produces methane



Andy Hughes of the British Dam Society points to Laos and Vietnam as shining examples ofdam-building countries that have harnessed hydropower. "They're building dams, they'regenerating hydropower, and then they export that power to other countries, so it's a big cashcrop for them," he says.

Debatable dams

Belo Monte, Brazil

Height of wall: 90m (295ft) Cost: $14.4bn (£8.6bn), predicted to rise to $27.4bn (£16.4bn) Problem: Construction halted in 2011 on environmental grounds; restarted in 2013

Three Gorges, China

Height of wall: 181m (594ft) Cost: $23bn (£13.8bn) Problem: Displaced 1.4m people, may have caused landslides

Diamer-Bhasha, Pakistan

Height of wall: 272m (892ft) Cost (2008): $12.7bn (£7.6bn) Problem: Experts predict construction costs may not be recovered

Gigel Gibe III, Ethiopia

Height of wall: 243m (797ft) Cost: $2.1bn (£1.3bn) Problem: Expected to disrupt fisheries and livelihoods of 500,000 inhabitants of the

Lower Omo Valley

But Bent Flyvbjerg, principal investigator for the Oxford University dam study, says dams "arenot carbon neutral, and they're not greenhouse neutral". The vast quantities of concreterequired to construct leave an enormous carbon footprint, he says.

Furthermore flooded vegetation under the reservoirs produces methane, a greenhouse gasroughly 20 times more potent than carbon dioxide, he says.

His argument is not with all dams though, but with megadams.

"We don't accept that it's a discussion of hydropower from large dams versus fossil fuels. Wewould like the discussion to be about hydropower from large dams versus hydropower fromsmaller hydropower projects," he says.



Others, such as Peter Bosshard of environmental campaign group International Rivers, sayclimate change threatens to alter weather patterns in unpredictable ways.

"So if you put all your energy eggs in one big dam, you're taking a big risk because you don'tknow what future rainfall patterns will be over time," he says.

The cost of these behemoths is the main focus of the Oxford study.Flyvbjerg says he expects the $14.4bn (£8.7bn) price tag for Brazil's Belo Monte dam to surgeto $27.4bn (£16.5bn), outweighing any benefits, and saddling the country with a mountain ofdebt.

Ethiopia's Nile dam could affect the river downstream, in Cairo

At least Brazil's economy is robust. For many emerging economies, massive dams spelldisaster, Flyvbjerg says. Some countries take out large loans - often in foreign currency,making them vulnerable to exchange rate fluctuations - and when dams don't deliver thepromised benefits, these nations take a huge hit.

"It's like a bull in a china store - these projects are way too big and way too risky to be taken onby the most fragile economies in the world," he says.

Even when a dam project is overrunning and costs are soaring, governments are reluctant toscrap them he points out.

"A dam is really a useless asset if it's not completely finished. Even if it's 99% finished, youcan't use it - it's either on or it's not," Flyvbjerg says.



But Andy Hughes says dams have many upsides. Critics should ask themselves a number ofquestions, he says: "How else would one generate power, how else would one give peopleclean water to drink, how else would one irrigate farms, how else would one treat sewage?"

Work on the Belo Monte dam was suspended by a judge in 2011, resuming two years later

And dams create employment. The Belo Monte hydroelectric dam project is projected to creatework for an estimated 20,000 people

He says they can play an important role in mitigating climate change. During droughtconditions, the reservoirs provide drinking water and irrigation. During wetter periods they'rekey for flood protection. In fact, Hughes predicts an upswing in dam building after severeflooding across the UK in the winter just gone by.

Julia Jones, an Oregon State University hydrologist, says this chimes with her study of dams inthe Columbia River basin in the Pacific Northwest.

A 19th Century dam disaster

As families slept, the raging torrent smashed into their homes, killing them instantly andwashing away all but the faintest traces of scores of buildings.

The body of one victim was reportedly found 18 miles downstream of his home while, in MalinBridge alone, 102 people were killed, including 11 members of one family.

"There's been a net increase in the availably of water during scarce times and the protection ofplaces during flooding times, which is exactly what the dams were intended to create," she



explains. "That suggests that there is resilience and that there may be capacity large enoughto deal with future climate change." But it all depends on how big the impact of climate changeis, she notes.

The real benefit of dams may simply boil down to perspective, according to Jones.

"It all depends on who's at the table," she says. "There has been a lot of controversy for half acentury or more about the larger context in which these projects are constructed - that is, wholoses their livelihoods, who gains from the construction of the dam and the environmentalbenefits and costs."

For Hughes, it's more of a damned-if-you-do-damned-if-you-don't trap.

"My view is that dams can never win. If we build a dam, we get criticised, but once the dam isbuilt people say, 'Well, what was all the fuss about? Isn't this a beautiful setting for walkingaround the lake and picnics?' But try and demolish a dam, and you get criticized for damagingthat beautiful environment. So it's a no-win exercise, I'm afraid."

do massive dams ever make sense

Documents