{{Short description|Lake in Gorno-Badakhshan, Tajikistan}} {{Use dmy dates|date=July 2025}} {{Infobox body of water | name = Sarez Lake | image = usoi.jpg | caption = Usoi Dam separating Sarez (right) and Shadau (left) lakes | image_bathymetry = | caption_bathymetry = | location = | coords = {{coord|38|12|06|N|72|45|27|E|region:TJ|display=inline,title}} | type = |pushpin_map=Tajikistan | inflow = Murghab River | outflow = Murghab River | catchment = | basin_countries = Tajikistan | length = {{convert|75.8|km}} | width = {{convert|3.3|km}} | area = {{convert|79.7|km²}} | depth = {{convert|201.8|m}} | max-depth = {{convert|505|m}} | volume = {{convert|16.074|km³}} | residence_time = | shore = {{convert|162|km}} | elevation = {{convert|3,263|m}} | frozen = | islands = | cities = | reference = | mapframe = yes | mapframe-zoom = 9 | mapframe-wikidata = yes }} thumb|upright=1.20|Satellite photo of the western end of Sarez Lake showing the Usoi Dam and the smaller Shadau Lake [[File:Usoi Dam in 2009, by Martin Mergili.jpg|thumb|upright=1.20|Usoi Dam, showing the outflow of Sarez Lake in the bottom left.]] '''Sarez Lake''' ({{IPAc-en|s|ə|ˈ|r|ɛ|z}} {{respell|sə-REZ}}){{efn|{{langx|tg|Сарез кӯл|Sarez ko‘l}}, {{IPA|tg|sɐˈɾes‿kʰɵl|IPA}}; {{lang-rus|Сарезское озеро|r=Sarezskoje ozero|p=sɐˈrʲesːkəje ˈozʲɪrə}}}} is a lake in Rushon District of Gorno-Badakhshan province, Tajikistan. Its length is about {{convert|75.8|km}}, its depth about a few hundred meters, its water surface elevation about {{convert|3,263|m}} above sea level, and volume of water over {{convert|16|km³}}. The mountains around it rise over {{convert|2,300|m}} above the lake level.
The lake formed in 1911, after a great earthquake, when the Murghab River was blocked by a big landslide. Scientists believe that the landslide dam formed by the earthquake, known as the Usoi Dam, is unstable given local seismicity, and that the terrain below the lake is in danger of catastrophic flood if the dam were to fail during a future earthquake.<ref>Bolt, B.A., W.L. Horn, G.A. Macdonald and R.F. Scott, (1975) '' Geological hazards: earthquakes, tsunamis, volcanoes, avalanches, landslides, floods'' Springer-Verlag, New York, {{ISBN|0-387-06948-8}}</ref> The Usoi Dam wall survived a localised 7.2 magnitude earthquake, the 2015 Tajikistan earthquake, on 7 December 2015 with no visible signs of deterioration.
'''Shadau Lake''' is a small water body southwest of the Usoi Dam and west of Sarez Lake.<ref name=map>{{cite web |url=http://www.pamir-adventure.com/pamirarchive/diverse/sarez.jpg |title=Shadau Lake on 1:110'000 map |format=JPG}}</ref>
==Formation== The formation of Sarez Lake is described in the book by Middleton and Thomas:<ref>Robert Middleton and Huw Thomas, ''Tajikistan and the High Pamirs'', Odyssey, 2008, {{ISBN|962-217-773-5}}, {{ISBN|978-962-217-773-4}}</ref> {{Quote| The 1911 Sarez earthquake, estimated at 6.5-7.0 on the Richter scale, occurred about midnight, 5–6 February 1911 (old style). Deaths were estimated at 302. The landslide was 2.2 billion cubic meters and formed the Usoi Dam which is approx. {{convert|5|km}} long, {{convert|3.2|km}} wide and up to {{convert|567|m}} high, the tallest natural dam in the world. Usoi was a village buried under the landslide. The area was so isolated and the destruction of mountain tracks so complete that it took six weeks before word reached the Russian posts at Murghab and Khorog.
In 1968 a landslide caused two-meter-high waves in the lake. A 1997 conference in Dushanbe concluded that the dam was unstable and might collapse if there were another powerful earthquake. A 2004 study by the World Bank held that the dam was stable. The principal danger seems to be a partially detached mass of rock of about 3 cubic kilometres that could break loose and fall into the lake. Since the valley below the dam is so narrow, any flood would be very destructive. The result of a global risk analysis carried out by STUCKY for the World Bank was presented at the 2002 IAHR Symposium in St Petersburg<ref>{{Cite web| title=Lake Sarez risk mitigation project: A global risk analysis | url=http://lmswww.epfl.ch/Common_Documents/Amis_LMS+R/Article_P.droz_IAHR-Sarez%20Article2.pdf | archive-url=https://web.archive.org/web/20110706225325/http://lmswww.epfl.ch/Common_Documents/Amis_LMS+R/Article_P.droz_IAHR-Sarez%20Article2.pdf | archive-date=2011-07-06}}</ref> and at the 2006 International Congress on Large Dams<ref>{{Cite web| title=Lake Sarez risk mitigation project: A global risk analysis | url=http://www.stucky.ch/en/contenu/pdf/c_5_1.pdf | archive-url=https://web.archive.org/web/20071031024001/http://www.stucky.ch/en/contenu/pdf/c_5_1.pdf | archive-date=2007-10-31}}</ref> in Barcelona. }}
==Notes== {{notelist}}
==References== {{Reflist}}
==External links== *[http://www.pamir-adventure.com/pamirarchive/diverse/sarez.jpg Map of the Usoi Dam - Sarez Lake, Scale 1:110'000] *[https://web.archive.org/web/20020202151035/http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=6773 NASA Earth Observatory photo] *[http://www.sarez.tj/index_en.shtml Sarez Risk Mitigation Project] {{Webarchive|url=https://web.archive.org/web/20111207045410/http://www.sarez.tj/index_en.shtml |date=2011-12-07 }} *[http://erg.globalnet.uz/sarez/sarez.html Sarez lake, Rogun HPP, Aral sea ...] {{Webarchive|url=https://web.archive.org/web/20130305004007/http://erg.globalnet.uz/sarez/sarez.html |date=2013-03-05 }}
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Category:Lakes of Tajikistan Category:Gorno-Badakhshan Autonomous Region Category:Landslide-dammed lakes Category:Landslides in Asia Category:Natural disasters in Tajikistan Category:1910s landslides Category:1911 natural disasters