Lake No.6 once again threatens Almaty with mudflow 25 мая 2011, 12:59
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lake number 6. Photo courtesy of time.kz
Mountain lake number 6 that threatened Almaty with devastating mudflow last year is “awake” again, professor Boris Stepanov told Vremya newspaper.
According to Stepanov, the water level in the lake has dropped by more than 10 meters during the winter. This confirms that there is an active filtration of the lake's water through the cavin into the moraine. This may cause a massive landslide or mudflow.
“I saw the pictures made by alpinists in the beginning of April; the lake number 6 is tiny on these pictures. This is a bad sign, because we don't know where and how the water left the frozen lake in winter. One thing is clear: it could not have evaporated,” he said.
As per the scientist, dispersed filtration means that the moraine is heavily saturated with water and may start sliding down the hill at some point. Then the water remaining in the lake will gush onto the city of Almaty. Another possibility is that the moraine may have a cavern through which the water leaves the lake in an unknown direction. In this case when the entrance or exit to the cavern is blocked by an ice or snow plug the lake will start refilling gain. This, again, can cause a natural disaster.
As per Stepanov, it is necessary to start geophysical research of the morainic lake as soon as possible.
“Whatever happens, slide of the water-saturated moraine or blocking of the cavern, it will result in a similar tragic experience as in 1973, when the lake number 3, currently non-existing, over-flooded into the Almaty foot hills. The mudflow was stopped by Medeo dam. Back then there was 220 thousand cubic meters of water rushing downhill. And now imagine that there would be about the same amount of water from the lake No. 6 plus the water that has gathered in the moraine. This together represents a much greater mass of water. The water has saturated the moraine like it would a sponge! This may have unpredictable consequences,” he said.
Almaty was devastated by mudflows coming down from the mountains several times: the two most disastrous happened in 1921 and in 1963. The 1973 mudflow was greater than all the previous ones and would have destroyed half Almaty should it reach the city, but it was luckily stopped by the large Medeo dam after crashing through several smaller dams. It still claimed lives of many tourists and mountain hikers.