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Radiation from Chernobyl Radiation from Chernobyl
What do the Chernobyl disaster, the Three Gorges dam in China and the spread of the Sahel have in common? In each case natural and manmade influences have forced thousands, sometimes millions of people, to leave their land or country of origin.
29 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Ore production and waste generation at Ok Tedi Mine Ore production and waste generation at Ok Tedi Mine
The Ok Tedi mine is located high in the rain forest covered Star Mountains of Papua New Guinea. Prior to 1981 the local Wopkaimin people lived a subsistence existence in one of the most isolated places on earth. That was before the 10 000 strong town of Tabubil suddenly appeared in the middle of their community. The Ok Tedi mine was built on the world’s largest gold and copper deposit (gold ore capping the main copper deposit). From the very begi...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Mercury pollution - transport and cycle Mercury pollution - transport and cycle
Mines use toxic chemicals including cyanide, mercury, and sulphuric acid, to separate metal from ore. The chemicals used in the processing are generally recycled, however residues may remain in the tailings, which in developing countries are often dumped directly into lakes or rivers with devastating consequences. The accidental spillage of processing chemicals can also have a serious impact on the environment. For example, at the Baia Mare mine ...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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River fragmentation and flow regulation River fragmentation and flow regulation
This graphic shows the number of new dams that were under construction in 1998. It also indicates the areas which are most affected by river channel fragmentation and flow regulation. River fragmentation is defined as the interruption of a river's natural flow by dams, inter-basin transfers or water withdrawal, and is an indicator of the degree to which rivers have been modified by human activity.
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Regulation in the Volga river, 1934 compared to 1999 Regulation in the Volga river, 1934 compared to 1999
The construction of a large number of dams and industrial facilities on the rivers feeding the Caspian has caused a significant change in the quantity of water inflow. The creation of a succession of large reservoirs, especially on the lower and middle Volga, has led to significant losses in flow rate due to additional evaporation from the surface of the water.
29 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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The inlet of the bay of Kara-Bogaz-Gol before and after the construction of the dam (Turkmenistan, Caspian Sea) The inlet of the bay of Kara-Bogaz-Gol before and after the construction of the dam (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 had biological consequences. In the spring of 1992, in view of the scale of the disaster, Turkmenistan, which...
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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Water flow from the Caspian Sea to the bay of Kara-Bogaz-Gol, 1930-2000 Water flow from the Caspian Sea to the bay of Kara-Bogaz-Gol, 1930-2000
Kara-Bogaz-Gol is a lowland area that forms a highly saline bay on the east side of the Caspian Sea, in Turkmenistan. Soviet leaders maintained that this was “a useless caldron for evaporation, an insatiable mouth swallowing up the precious water of the Caspian Sea” and obviously to blame. The dam, finished in 1980 blocked the flow of the water between the Caspian Sea and Kara-Bogaz-Gol. This reduced the water levels in the bay while increasing d...
07 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Kara-Bogaz-Gol, desertification while dammed 1980-1992 (Caspian Sea, Turkmenistan) Kara-Bogaz-Gol, desertification while dammed 1980-1992 (Caspian Sea, Turkmenistan)
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. Much to everyone’s surprise the Kara-Bogaz-Gol bay dried up 10 times faster than had been forecast by the Institute of Hydraulic Affairs and by autumn 1983 it was all over. The pink flam...
07 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Industrial hot spots Tisza river basin Industrial hot spots Tisza river basin
On 30 January 2000 a tailings dam at the Aurul Mine in Romania overflowed and released 100,000 cubic metres of effluent containing cyanide into the Tisza River. By the time the overflow was detected, the alarm raised and emergency measures taken to staunch the flow, heavily contaminated wastewater had reached the Danube River and was on its way to Hungary and beyond. Traces of cyanide, albeit at a very low level, were still detected in the rive...
01 Feb 2006 - by Emmanuelle Bournay, UNEP/GRID-Arendal
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Formation of lakes and glacier lake outburst floods (GLOFs) by Medvezhi Glacier, Pamirs Formation of lakes and glacier lake outburst floods (GLOFs) by Medvezhi Glacier, Pamirs
The increasing number of glacial and moraine lakes in Central Asian mountains is a matter of great concern. One of the surging glaciers that poses a potential threat is the 15 km long Medvezhi (Bear) Glacier in the Pamirs mountains of Tajikistan. Its surges have repeatedly caused lake formation, outburst and subsequent floodings. In 1963 and 1973, the surge of the glacier was so significant (1 to 2 km increase in length) that the ice dam exceeded...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Level of river fragmentation and flow regulation Level of river fragmentation and flow regulation
River fragmentation - The interruption of a river’s natural flow by dams, inter-basin transfers or water withdrawal - is an indicator of the degree to which rivers have been modified by man (Ward and Stanford, 1989, and Dynesius and Nilsson, 1994, as cited in Revenga et al., 2000). A fragmentation analysis carried out by the University of Umea and the World Resources Institute showed that, of 227 rivers assessed, 37% were strongly affected by fra...
26 Jan 2009 - by Philippe Rekacewicz (Le Monde diplomatique), March 2006
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Damming the world Damming the world
The construction of large dams - defined as those with walls at least 15 metres high - has increased significantly over the past 50 years. The average height of new dams, estimated at 30-34 m from 1940-1990, increased to about 45 m in the 1990s, due largely to construction trends in Asia. The average area and volume of freshwater reservoirs have also steadily increased, rising to about 50 km2 between 1945 and1970, declining through the 1980s to 1...
26 Jan 2009 - by Phillippe Rekacewicz, February 2006
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