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Tropical hydropower dams as greenhouse sources Tropical hydropower dams as greenhouse sources
Large tropical hydropower reservoirs in Latin America may have a potential adverse impact on the climatic system through releasing greenhouse gases into the atmosphere. Submerging large areas of land and tropical vegetation under water and fluctuations in water level promote physical-chemical processes that decompose the organic matter and generate methane and carbon dioxide emissions. In the initial years of operation, emission levels are especi...
17 May 2005 - by Viktor Novikov, UNEP/GRID-Arendal
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Annual flow of water to the Caspian Sea Annual flow of water to the Caspian Sea
Most of the water flowing into the sea comes from coastal rivers – currently supplying 300 to 310 cubic km a year. The Volga alone accounts for 80% of inflow. But it has dropped substantially during the 20th century, declining from about 400 cubic km in the 1920-30s to between 260 cubic km and 270 cubic km at present, due to various climatic factors and human activities such as dams built for hydroelectric energy production.
29 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Kara-Bogaz-Gol - restoration of previous water levels after 1992 (Turkmenistan, Caspian Sea) Kara-Bogaz-Gol - restoration of previous water levels after 1992 (Turkmenistan, Caspian Sea)
Kara-Bogaz-Gol is a lowland area that forms a highly saline bay on the east side of the Caspian Sea, in Turkmenistan. In Soviet times it was decided to set up a dam to block the flow of saline water from the bay to the Caspian Sea, and this was completed in 1980. The ensuing increase in the salt content of the southern part of the Caspian Sea, to levels exceeding 15 grams per litre, had disastrous consequences for the sturgeon population. In the ...
29 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Kara-Bogaz-Gol - water level variation over time Kara-Bogaz-Gol - water level variation over time
Comparing a series of satellite images from different periods a Californian hydrologist discovered in 1983 that a huge white spot had taken the place of the vast Kara-Bogaz- Gol (literally “dark gullet” in Turkmen) in the south-east corner of the Caspian. Kara-Bogaz-Gol is a lowland area that forms a highly saline bay on the east side of the Caspian Sea, in Turkmenistan.
07 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Example of enhanced water levels produced from river ice, Liard River, Canada Example of enhanced water levels produced from river ice, Liard River, Canada
The lower curve shows the correspondence between river flow and water levels under open-water conditions. The much greater maximum water levels possible under ice-jam conditions are illustrated by the upper curve. The transition in break-up severity from dynamic to thermal break-up effects (see text) is depicted by the gradually shaded area between the two curves. Dots are observed annual maximum water levels during the spring break up. The 1990...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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