Sarez Lake
The Saressee ( Tajik кӯли Сарез Köli Sarez ) is a lake in eastern Tajikistan (Central Asia ).
Geography
The usually deep blue lake is located in the territory of Gorno-Badakhshan in the high mountains of the Pamir. There he is located approximately 75 km (air line ) west of the city of Murghab. It is drained by the river Murghab.
History
The Saressee was taken on February 18, 1911 by a gigantic landslide that was triggered by an earthquake in the presumed force 8 to 9 on the Richter scale, the deep valley of the river Murghab with about 2 to 2.2 km ³ of soil and rock material is completely sealed off and the village Usoi buried among themselves.
This landslide was also the Shadausee, another small lake, which is at right angles slightly away from the Saressees to the southwest.
The resulting by the landslide and named after the buried village Usoi Dam (also Usoj or Usojskij - spillage or obstruction - called ) is a remarkable 5 km long and at the base of a maximum of 3.2 km wide at the crown. At the highest point of his dam he is about 567 m high. He is the highest naturally formed mound of earth and exceeds the height of the tallest man-made dam ( Nurek Dam ) significantly.
In the years following the creation of the Damm Murghab river formed a 55.8 km long, a maximum of 3.3 km wide and up to 500 m deep lake or pond, containing a maximum of 16.074 km ³ of water, which is more than five times the volume of Lake Starnberg. The water level of Saressees is more than 38 m below the lowest point of the dam crest. The Saressee (as well as the Shadausee ) has no open drain; its water seeps through the dam and enters on its side of the valley about a hundred meters deep in a " source " as mountain stream with a flow rate of 35 to 70 m³ / s again.
The Saressee is lined with many mountains and mountain ranges, which to project over the in 3263 m altitude at the current full back surface of the water, which was estimated in a measurement of 1987 to 79.6 km ² at least 2416 m. For example, is located just north of the dam, a 5679 m high, glaciated mountain, the south two 5525 m and 5273 m high mountains are upstream, the directly adjacent hillsides were the place of the landslide of 1911. Due to the mostly very steep and at the same time non-vegetated mountain slopes, the lake hardly trained riparian areas, so that it is not or only moderately traffic on roads and paths, for example, lead to the dam opened up.
The Saressee or Usoi Dam is one of several, smaller and larger lakes or Einsturzversperrungen caused in Tajikistan and the Pamirs by earthquakes.
Source of danger
Geologists fear that the potentially unstable Usoi dam could break during another strong earthquake, which would lead to a devastating disaster:
If the dam actually would break, the waters of the Saressees on the Murghab, Bartang, the Panj and Amu Darya would pour into the direction of the Aral Sea and flood not only the shore regions of this river course in Tajikistan, Afghanistan, Uzbekistan and Turkmenistan. Of these, approximately 5 million people as well as the flora and fauna would be affected in the region. Here, an initially 150 to 170 m high tsunami would pour into the valley, according to research that could have the height of a two story house still on the Amu Darya.
In addition to an earthquake that provides out of the lake water flowing out of a potentially dangerous, the sea water does not overflow its crown, but seeps into the seaward slope. It is feared that the filtration of water while rinsing always larger cavities, whereby the Usoi dam would gradually lose stability. On the tal- or air-side slope water occurs far below the dam crown back as a mountain river; below this "source" of Murghab is in the area of the dam from a constantly growing canyon, so that the dam will be gradually removed. Because of the addition, the glaciers of the Pamir melt in increasing measure because of global warming, the water level is an increase of nearly 25 m, which increases the water pressure on the dam and the lake area has increased in recent years, from 3239 m to 3263 m above sea level on, on swelled just over 80 km ². In the winter half years ago when the glaciers freeze again, the water table is falling by up to 12 m, then increases again.
Much bigger than the risk of dam failure is a foreseeable collapse or a collapse of a dam in the 4 km to the opposite rock wall, on which a 1.5 km long fissure has formed. Even with a slight earthquake, this wall could plunge into the lake, with about 0.5 to 1 km ³ of rock would slip into the Saressee. The force generated by the water displacement tidal wave would drive the masses of water against the shore and possibly over the dam. In the worst case this would lead to partial or total collapse of the dam, which would result in the valleys below the dam to disaster.
Because of all these hazards, earthquake monitoring system was installed in 2004 at Usoi Dam. In parallel, sirens were built in the river downstream in the Murghab or Bartang valley villages that are powered by solar and battery power, so that they are ready for use, ideally around the clock.