Saturday, June 9, 2012

Glaciers, Dams and Chile's Baker River

Four years ago, the Baker River in Aysén Patagonia suddenly tripled in size, causing a virtual river tsunami. In less than 48 hours, roads, bridges and farms were severely damaged and dozens of livestock drowned. Residents were in disbelief. Jonathan Leidich, an American whose company regularly leads tourists on treks up to nearby glaciers, hiked to the Colonia Glacier at the eastern flank of the Northern Patagonian Ice Field and discovered the source of the mysterious flood: Lake Cachet 2 had vanished. This enormous, two-square-mile glacial lake had emptied its 200 million cubic meters of water in just a matter of hours.

cachet_fullLake Cachet 2 before the GLOF...

What happened? Glaciologists say it was yet another “glacial lake outburst flood,” or GLOF. An increasing rate of melting at the Colonia Glacier swelled the lake so much so that the resulting water pressure gradually forced the creation of a tunnel beneath the surface of the adjacent ice and drained the lake. Since Cachet 2 emptied in 2008, the lake has “disappeared” ten more times.

cachet_empty....and after. Photos courtesy of Patagonia Adventure Expeditions.

Such GLOFs don’t necessarily arise because of climate change; indeed, some four decades ago a GLOF occurred on the Baker River. But a clear warming trend over the past decade has taken its toll on the world’s glaciers, and it is widely agreed that climate change is dramatically increasing the frequency and intensity of GLOFs.

In December 2010, the United Nations Environment Programme (UNEP) released a report on mountain glaciers at the climate-change talks in Cancún, Mexico, stating that glaciers on Argentine and Chilean Patagonia are “losing mass faster and for longer than glaciers in other parts of the world.”

“Accumulation of science shows us a clear general trend of melting glaciers linked to a warming climate,” UNEP executive director Achim Steine said.

Glaciers on the Chilean side of Patagonia account for more than 90 percent of the Patagonian region’s ice fields. Those fields consist of two non-contiguous sheets: the Northern Patagonian Ice Field, which includes Cachet 2, and the Southern Patagonian Ice Field, the world’s third-largest continental ice sheet after those of Antarctica and Greenland.

Data show that since 1995, the rate of thinning has more than doubled. Studies from NASA show that the Patagonian Ice Fields, which extend some 6,600 square miles altogether, account for about 9 percent of annual global sea level change from mountain glaciers.

Skeptics of global warming point to some Patagonia glaciers that remain stable, or that are even growing, such as Argentina’s Perito Moreno Glacier. But Gino Casassa, director of Glacier and Climate Change Research at the Center for Scientific Studies, said global warming can also lead to more rain, or snow in the case of regions such as Patagonia.

“We have scientific evidence showing a new cycle of activity in GLOFs in Patagonia and not just Lago Cachet,” Casassa said. “Glaciers are melting and lakes growing in size throughout the region — a clear sign of global warming. We will see GLOFs more often.”

Casassa said that in part, Patagonian glaciers are more susceptible to global warming because they are dominated by so-called “calving glaciers,” which release icebergs into lakes or the sea. There are also other climate change effects that intensify melting, such as elevation feedback. 

“As a glacier thins, the (upper edge retreats to lower elevations) — often in Patagonia by about five meters (16 feet) per year,” he said. “As that happens, atmospheric temperatures get warmer because you are at a lower elevation. This can be important in speeding up the melting of a glacier.”

The GLOFs are not just happening at an increasing rate in Patagonia, but worldwide in countries that are home to mountain glaciers. In April 2010, a huge slab of ice the size of several football fields broke off a glacier on Mount Hualcán and plunged into a lake in central Peru, creating a tsunami-like wave at least 76 feet high that flooded four towns, destroyed at least 50 homes and severely damaged a water plant serving a town of 60,000 people.

This accident came on the heels of the warmest summer season on record in the Southern Hemisphere, according to NASA’s Goddard Institute for Space Studies.

Compared with other countries, Peru is unusually well-prepared to cope with sudden lake floods, experts say. The Peruvian Andes mountain chain has witnessed more than 30 glacial floods in the past, killing nearly 6,000 people altogether since 1941. As a result, the Peruvian government has invested millions of dollars in working to drain or dam glacial lakes to lessen the hazardous risks.

Yet despite significant initiatives to safeguard nearby towns, Lake 513 on the slope of Mount Hualcán burst. Peru is experiencing rapid glacial change.

A 2009 World Bank report states that, due to warmer temperatures, Peru’s glaciers have declined 22 percent since 1975 and are likely to disappear in two decades, threatening to provoke more floods and eliminating a major source of water and hydropower for its people. In the Himalayan region of Nepal, China, Bhutan, India and Pakistan, the International Center for Integrated Mountain Development has identified 200 “potentially dangerous” glacial lakes.

Scientists predict that several major rivers fed by the Himalayas, such as the storied Ganges River in India, are set to be affected by massive glacial floods in the years ahead and eventually, as the glaciers retreat, the site of serious water shortages for untold millions of people during dry seasons.


GLOF events at the Baker River in Chilean Patagonia, considered Chile’s largest river in terms of water volume, can sometimes raise the river up to 18 feet in some areas. Historically, GLOFs have been known to increase water flow to as much as 45,000 cubic feet per second.

“The lake is growing in size after every GLOF,” the 38-year-old Leidich said. “Which means the floods are just going to be more devastating in the future.”

Especially worrisome to Leidich and others is the combined effect these GLOFs may have together with a series of controversial large dams planned for the Baker River as part of a US$10 billion HidroAysén project.

The companies pushing the project, Endesa Chile, owned by Italy’s Enel, and Chile’s Colbún, hope to get the first of their Baker River dams readied by 2015. But a possible GLOF-related accident at the dam could wipe out the 512-person Tortel, a small, tranquil village located at the mouth of the Baker River, where the river merges with the Pacific Ocean.

Tortel is already issuing GLOF-evacuation orders for its residents as the high-water mark of the Baker River hits new peaks with the GLOF events. A study by the Physics Department at Santiago’s Metropolitan Technology University found that if a dam on the Baker were to break, Tortel would suffer “catastrophic consequences” within less than an hour.

“This project goes against the development and future of Tortel,” Bernardo Lopez, mayor of Tortel, said.

HidroAysén has said that it has considered in its engineering studies potential GLOFs based on nearly 50 years of past history of GLOFs. But Alejandro Dussaillant, a Chilean expert on hydrology at Greenwich University in England who has studied closely the Lake Cachet GLOF and its effects on the river, said several factors could overwhelm HidroAysén´s projections.

“Up to now we have been lucky because up to now we have not had the worst-case scenario, which is the Baker floods, there is a GLOF from the Colonia glacier and both happen during high tide near Tortel.  As an engineer, we must always consider such extreme scenarios,” Dussaillant said.

“What has been happening up to now does not mean that it will be the same over the next 20 years. There are dynamic changes occurring to the source of the GLOFS, the glaciers and the system of lakes upstream from Lake Cachet 2, that must be studied further,” he added.

In addition to flooding, the GLOFs transport tremendous amounts of sediment, which not only contribute to higher flood levels but reduce the life span of the dam downstream by accumulating sediment in the reservoir and potentially damaging the turbines.

Brian Reid, a limnologist with the Coyhaique-based Centro de Investigación en Ecosistemas de la Patagonia (CIEP), is conducting regular research on the Baker River. Reid said when a GLOF occurs, the river not only increases greatly in size but it contains the maximum amount of sediment the river can hold.

“The idea of building a major dam on one of the most unstable rivers on the planet seems crazy to me,” he said. “For the amount of risk involved in this dam project from these GLOFs, the company’s responses in the environmental evaluation process have been completely irresponsible.”

Despite the widely-shared concerns by scientists over GLOF risks associated with the proposed dams, the Aysén Regional Environmental Commission in November 2010 accepted the company’s views regarding GLOFs, and it was no longer an issue in the evaluation process when the project was approved in May 2011.

Leidich has met with Chilean senators, government ministers and others to seek financing for protection measures for ranchers and others living along the Baker. His efforts led to the creation of an early-warning system called the Sentinel Project in October 2008. High-frequency radios, powered by solar panels and batteries, were distributed to most families in the flood zone so they can receive warnings. But Leidich said the program will not work the way it needs to in the long term until it receives adequate annual funding.

Leidich calls HidroAysén a “blasphemy.” The companies say their dams, with an early warning system in place, can handle a GLOF of up to 23,100 cubic feet per second of water, which is the most their predictions say they will have to deal with in the future. Leidich said he is skeptical.

“What it will mean to the people living in Tortel and all along the river when the dam has to release that amount of water? The answer: Everyone downstream is wiped out.” Leidich said. “This place is a canary in the coal mine for global warming,” he added. “If people want to see whether climate change is for real, here it is.”

Written by Jimmy Langman@The Santiago Times

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