Monday, October 29, 2007

Chile's Puelo River: Diminishing water volumes impact residents and Endesa dam proponents.

(Oct. 29, 2007) A recent study confirmed that the volume of water in Region X’s Puelo River dropped by 16 percent in the last 60 years – a finding that could have implications for a hydroelectric dam planned for the river.

The Puelo River is among the most important rivers in Chile, with an average volume of 644 cubic meters per second. Energy giant Endesa has announced plans to build a hydroelectric dam project on the river, even though only 33 percent of the Puelo’s 8,817 km sq river basin belongs to Chile. The rest belongs to Argentina.

The importance of the area has prompted studies from various Chilean universities, including Universidad Austral and Universidad de Chile. A research team led by forestry engineer Antonio Lara reconstructed the river’s volumes since the year 1600 by carefully studying tree rings, which provide a natural record for water levels well before measuring stations were established in the area.

“Measurements were taken from about 100 trees, and the result is a zig-zag which shows an overall decrease,” said Lara.

The decrease in volume can be attributed to various factors, but appears mainly due to declining rainfall. “The pattern of decline is directly associated with the decrease in precipitation measured by meteorological stations since 1993,” said Rocío Urrutia, a researcher with the Núcleo Cientifico Forecos of the Universidad Austral. “This pattern is also supported by data from the Intergovernmental Panel on Climate Change (IPCC), which notes a 30 percent decrease in precipitation between 1900 and 1999.”

Although some decreases (and subsequent increases) in the river’s volume is a natural part of riparian cycles, the intensity of the Puelo River’s most recent lows could be cause for concern for both residents and dam proponents. In 1992, the river’s average volume registered at 347 cubic meters per second, the river’s lowest in the last 400 years. “These changes are associated with climate change,” said Urrutia.

The big question is whether these findings might have implications for current plans to build a hydroelectric dam on the Puelo River. The Endesa electricity company owns water rights for 850 cubic meters per second on the Puelo River, when the actual average is 644. “It seems there may not be enough water for them,” said Lara.

*(The problem of dimishing water and galciers in the Andes is becoming a concern throughout South America: When Ice Turns to Water , As glaciers melt, Chile's future uncertain .)

Here is the full article.