Are Large Dams Altering Extreme Weather Patterns?
source: http://www.livescience.com/environment/091203-dam-weather.html
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"Large dams may cause shifting regional weather extremes.
This finding is causing scientists to wonder if aging dams around the world can withstand the extreme weather events they may inadvertently generate.
It was nearly 75 years ago that scientists first speculated that large dams could vastly transform local climate. Weather results from the interaction of warm and cool air, and dams can hold vast reservoirs of water that can influence the heat and moisture of the air above them. Dams also can radically alter irrigation patterns in the surrounding land, impacting their climate patterns as well.
A number of recent studies and computer models suggest that dams can indeed boost rainfall by increasing atmospheric moisture.
"The findings are still preliminary, but we do see a trend," said researcher Faisal Hossain, a hydrologist at Tennessee Technological University in Cookeville.
"The idea that large dams built since the '30s and '40s to protect us from floods can come back to haunt us is a very provocative one," Hossain said.
As these dams have aged, they have lost a lot of how much water they can store because a lot of accumulated silt and sediment, meaning flooding or even bursting can become more of a concern.
"Typically, in 20 or 30 years, even 30 to 40 percent of storage can get lost because of sediment," Hossain said. "And if we want to handle rainfall that might become more extreme, we really need more storage."
http://www.livescience.com/environment/091203-dam-weather.html
This finding is causing scientists to wonder if aging dams around the world can withstand the extreme weather events they may inadvertently generate.
It was nearly 75 years ago that scientists first speculated that large dams could vastly transform local climate. Weather results from the interaction of warm and cool air, and dams can hold vast reservoirs of water that can influence the heat and moisture of the air above them. Dams also can radically alter irrigation patterns in the surrounding land, impacting their climate patterns as well.
A number of recent studies and computer models suggest that dams can indeed boost rainfall by increasing atmospheric moisture.
"The findings are still preliminary, but we do see a trend," said researcher Faisal Hossain, a hydrologist at Tennessee Technological University in Cookeville.
"The idea that large dams built since the '30s and '40s to protect us from floods can come back to haunt us is a very provocative one," Hossain said.
As these dams have aged, they have lost a lot of how much water they can store because a lot of accumulated silt and sediment, meaning flooding or even bursting can become more of a concern.
"Typically, in 20 or 30 years, even 30 to 40 percent of storage can get lost because of sediment," Hossain said. "And if we want to handle rainfall that might become more extreme, we really need more storage."
http://www.livescience.com/environment/091203-dam-weather.html
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