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Posts tagged "dam"

E.g., the case for removing old dams to restore ecosystems.

At over 100 sites throughout the Connecticut River basin, the largest river system in New England, we characterized species composition, valley and channel morphology, and hydrologic regime to define conditions promoting distinct floodplain forest assemblages. Species assemblages were dominated by floodplain-associated trees on surfaces experiencing flood durations between 4.5 and 91 days/year, which were generally well below the stage of the two-year recurrence interval flood, a widely-used benchmark for floodplain restoration. These tree species rarely occurred on surfaces that flooded less than 1 day/year. By contrast abundance of most woody invasive species decreased with flooding.
Such flood-prone surfaces were jointly determined by characteristics of the hydrograph (high discharges of long duration) and topography (low gradient and reduced valley constraint), resulting in increased availability of floodplain habitat with increasing watershed area and/or decreasing stream gradient. Downstream mainstem reaches provided the most floodplain habitat, largely associated with low-energy features such as back swamps and point bars, and were dominated by silver maple (Acer saccharinum). However, we were able to identify a number of suitable sites in the upper part of the basin and in large tributaries, often associated with in-channel islands and bars and frequently dominated by sycamore (Platanus occidentalis) and flood disturbance-dependent species.
Our results imply that restoring flows by modifying dam operations to benefit floodplain forests on existing surfaces need not conflict with flood protection in some regional settings.

"American eels were once found in great abundance on the East Coast, often quite far inland, but dams have sealed off much of their routes and their population has plummeted. However, the good news is that some of those old dams are no longer needed and are being torn down.

In 2004 the 22-foot-high Embrey Dam on the Rappahannock River in Virginia was dismantled. Since then, American eel numbers have shot up in headwater streams nearly 100 miles away, according to research just published by the U.S. Geological Survey, U.S. Fish and Wildlife Service, and National Park Service.

Researchers measured eels in Shenandoah National Park streams and found significant increases in numbers two years after the dam came down, with those gains accelerating since.

“Our study shows that the benefits of dam removal can extend far upstream,” Nathaniel Hitt, a USGS biologist and lead author of the study, said in a statement.  “American eels have been in decline for decades and so we’re delighted to see them begin to return in abundance to their native streams.”

The study authors noted that the American eel is being considered by the U.S. Fish and Wildlife Service for listing as a threatened species under the Endangered Species Act.”

Via National Geographic

Spectacular video of a dam removal. Check out all the built-up silt!

Cool find. Mayan’s built “sustainable” water infrastructure.


Recent excavations, sediment coring and mapping by a multi-university team led by the University of Cincinnati at the pre-Columbian city of Tikal, a paramount urban center of the ancient Maya, have identified new landscaping and engineering feats, including the largest ancient dam built by the Maya of Central America.

That dam – constructed from cut stone, rubble and earth – stretched more than 260 feet in length, stood about 33 feet high and held about 20 million gallons of water in a man-made reservoir.

These findings on ancient Maya water and land-use systems at Tikal, located in northern Guatemala, are scheduled to appear this week in the Proceedings of the National Academy of Sciences (PNAS) in an article titled “Water and Sustainable Land Use at the Ancient Tropical City of Tikal, Guatemala.” The research sheds new light on how the Maya conserved and used their natural resources to support a populous, highly complex society for over 1,500 years despite environmental challenges, including periodic drought. Read more.

Update: This is a photo from LA Times's Mel Melcon.

Update: This is a photo from LA Times's Mel Melcon.

Hundreds of dams across the US are candidates for removal. Dam removal restores river health, ecosystems, and habitat - all of which have economic benefits, such as increased property value and recreation opportunities.

"For 98 years, the 125-foot high Condit Dam in southeastern Washington State held back the White Salmon River, creating a serene lake, but choking off the waterway to salmon. Wednesday, in an historic effort, the dam was dramatically breached, and ecologists hope the increased flow of water will restore the waterway to fish and other aquatic organisms, as well as the birds and mammals that rely on them.

The dam removal comes just weeks after dismantling began on the Elwha Dam a few hours to the north. Demolition of the Condit occured with a bang, compared to the virtual whimper of the Elwha. At that site, downstream from Olympic National Park, engineers are dismantling the two dams slowly, in a process that’s expected to take three years. They say a quicker removal would endanger the area due to the higher amount of silt in the lake.

Silt is still readily apparent in the dramatic video above, both in the darkly colored water rushing from underneath the conrete and in the fast-emptying lake.

To capture the action in the above video, Andy Maser of Maser Films set up several cameras, starting in July. He plans on documenting the changes in the basin in the ensuing months. Maser used a combination of still and video recording, compiled on his computer after he was able to retreive the data from his cameras.”

Source: National Geographic

Brazil judge halts work on Belo Monte Amazon dam.

Judge Martins barred the Norte Energia company behind the project from “building a port, using explosives, installing dikes, building canals and any other infrastructure work that would interfere with the natural flow of the Xingu river, thereby affecting local fish stocks”.

Legal battle

He said the building of canals and dikes could have negative repercussions for river communities living off small-scale fishing.

The judge said building work currently underway on accommodation blocks for the project’s many workers could continue as it would not interfere with the flow of the river.

The consortium behind the project is expected to appeal against the decision.

In June, the Brazilian environment agency backed the construction, dismissing concerns by environmentalists and indigenous groups who argue that it will harm the world’s largest tropical rainforest and displace tens of thousands of people.

The agency, Ibama, said the dam had been subjected to “robust analysis” of its impact on the environment.

The 11,000-megawatt dam would be the third biggest in the world - after the Three Gorges in China and Itaipu, which is jointly run by Brazil and Paraguay.

Source: BBC

The march of progress: Ethiopia Moves Forward with Massive Nile Dam Project. The dam’s capacity is expected to be around 5,000 megawatts, which is about 5x the average nuclear power plant.

When completed in 2015, the Grand Millennium Dam will be the largest hydroelectric power plant in Africa. It will also create the country’s largest artificial lake, with a capacity of 63 billion cubic meters of water—twice the size of Lake Tana in Ethiopia’s Amhara region.


Retracing steps of an engineer who 100 years ago helped build the infrastructure of Southeast Asia. Sorry I missed this when first published. Thomas Fuller, following footsteps of his great grandfather. Fuller is one of my favorite NYT/IHT reporters.

Chile approves huge dam project on wild rivers, opening remote Patagonia to development

Robert F. Kennedy Jr. of the NRDC appeals. Patagonia is a huge mountain chain in South America. It’s the source of thousands of rivers. The Chilean slopes are of the most beautiful places on planet earth.

The commissioners — all political appointees in President Sebastian Pinera’s government — concluded a three-year environmental review by approving five dams on the Baker and Pascua rivers in Aysen, a mostly roadless region of remote southern Patagonia where rainfall is nearly constant and rivers plunge from Andean glaciers to the Pacific Ocean through green valleys and fjords.

But, in reading through the article, I’m having a hard time forming an argument against the project. Only three families will be relocated and only 14,000 acres will be clear-cut and flooded. That’s not much. There are few animals there, none particularly vulnerable.

Chile’s economy and population is exploding. Wealth is increasing, and they frankly need more electricity. Most of the country’s electricity comes from hydro, rather than more destructive coal or risky nuclear power. This dam will generate 2.75 gigwatts of power (trust me, that’s really a lot of power!). On top of this, the government and the investors will create jobs, major infrastructure, and much needed investments in education. These are substantial concessions, which are quite rare in development projects of this scale. 

The Aysen region will receive less expensive energy, jobs, scholarships and $350 million in infrastructure, including seaports and airports, said HidroAysen’s executive vice president, Daniel Fernandez.

Source: WaPo

UPDATE: Bloomberg is reporting loud protests.

Thousands of Chinese citizens protest forced resettlement by hydro dam, clash with police. Over 100,000 people will be displaced and paid $250 per year. A sign of the new normal. Story here, and here.

Over 50 people were injured in a five-day-long standoff between police and thousands of protesters over land confiscation in China’s Yunnan Province. A thousand armed police in military vehicles were dispatched and local officials cut off the Internet connection of the entire town.

Residents of Suijiang County, Yunnan Province, who were forced to leave their homes because of the construction of the Xiangjiaba hydraulic power station, were upset over meager resettlement compensation.

The costs of growing populations. One of the toughest environmental arguments to make. Do you side with 23 million people who need electricity, or do you side with 20,000 indigenous people and a sliver of the Amazon rainforest and all its riches? Should they turn to nuclear power, and if so, how to pay for, monitor, and maintain it?

The proposed Belo Monte Dam in northern Brazil would be the third largest hydro-electric dam in the world in terms of electrical output. The dam would be 3.75 miles long and generate over 11,000 megawatts, which could power up to 23 million homes. Government officials say that the dam is an essential step in supplying energy to the nation’s growing population. However, the project is rife with environmental conflicts. The project requires the clearing of 588 acres of Amazon jungle, the displacement of over 20,000 indigenous people, flooding a 193 square mile area, and drying up a 62 mile stretch of the Xingu River.

Image source: Electrobras via BBC, article here.

H/T: envirolutionary