Sarez Lake
Interesting facts
- Only three people from the buried village of Usoi survived the 1911 landslide, because they were away at a festival in the village of Sarez.
- Survivors said the cloud of dust hanging over their vanished village took three days to settle.
- Scientists long argued whether the quake caused the landslide or the reverse; in 1915 Prince Boris Golitsyn calculated that the rockfall alone could have done it.
- At least nine earlier landslide lakes formed in the same valley over the Quaternary and vanished when their natural dams gave way.
- Until 1925 the lake deepened by about nine metres a year; the first springs broke out at the foot of the dam in 1914, and by 1939 there were 57.
- The water seeping through the dam flows at about 45 cubic metres per second, carrying energy equivalent to roughly 250 megawatts.
- Only the top 50 metres or so of the lake is very fresh, oxygen-rich water; below lies a stagnant, highly mineralised layer with little oxygen.
- In 1968 a landslide into the lake raised waves about two metres high.
- Birch groves grow by the lake at up to about 3,700 metres and poplars up to 3,800 metres, higher than trees reach anywhere else in the Pamirs.
Why it is worth it
High in the Pamirs, a long ribbon of turquoise water fills a valley that held only a river until a winter night in 1911. Sarez Lake lies at about 3,260 metres above sea level in the Rushon District of Gorno-Badakhshan, eastern Tajikistan, hemmed in by slopes that climb more than two kilometres above its surface. It stretches for some 60 to 75 kilometres, depending on the survey, yet is only a few kilometres wide, holds around 16 cubic kilometres of water and reaches depths of some 500 metres — a mountain fjord with no sea anywhere near it.
The lake is the product of a single catastrophe. On 18 February 1911 a strong earthquake struck the central Pamirs, and a mountainside of roughly two cubic kilometres of rock broke away and fell across the valley of the Murghab River. It buried the village of Usoi entirely, and the rock mass it left behind, now called the Usoi Dam, stands around 567 metres high — the tallest dam on Earth, natural or built. Behind it the river slowly backed up over the following months, and within a year the rising water had drowned the village of Sarez, some 20 kilometres upstream, which gave the lake its name. The upper Bartang valley was so cut off that news of the disaster took weeks to reach the Russian posts at Murghab and Khorog. A smaller companion, Shadau Lake, sits just southwest of the dam.
No water flows over the top of the barrier. Instead the lake seeps out through the base of the landslide at roughly the rate the river feeds it, so the level stays nearly constant, and the stream re-emerges below the dam to continue west as the Bartang. Because the Pamirs are seismically restless, geologists have studied the dam for decades, weighing the risk that a future earthquake or a fresh rockfall into the lake could breach it; it came through a magnitude 7.2 earthquake in December 2015 without visible damage.
Getting there
Sarez Lake lies in the remote eastern Pamirs, about 126 km in a straight line from Khorugh, the regional centre of Gorno-Badakhshan on the Pamir Highway. The approach is from the west up the Bartang valley, which meets the Panj near the town of Rushon. The nearest airport by straight line is Fergana International Airport (FEG) in Uzbekistan, about 246 km away across the mountains and a border; within Tajikistan the nearest is Kulob International Airport (TJU), about 248 km away, while Dushanbe is the country's main international gateway.
On these lists
From the encyclopaedia
Sarez Lake is a lake in Rushon District of Gorno-Badakhshan province, Tajikistan. Its length is about 75.8 kilometres (47.1 mi), its depth about a few hundred meters, its water surface elevation about 3,263 metres (10,705 ft) above sea level, and volume of water over 16 cubic kilometres (3.8 cu mi). The mountains around it rise over 2,300 metres (7,500 ft) above the lake level.
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