The Medeu Mudflow Control Dam (, ''Medeý bógeti'') is a dam across the Medeu Valley south-east of

Almaty Almaty, formerly Alma-Ata, is the List of most populous cities in Kazakhstan, largest city in Kazakhstan, with a population exceeding two million residents within its metropolitan area. Located in the foothills of the Trans-Ili Alatau mountains ...

, Kazakhstan, designed to protect the city from devastating debris flows (or

mudflow A mudflow, also known as mudslide or mud flow, is a form of mass wasting involving fast-moving flow of debris and dirt that has become liquified by the addition of water. Such flows can move at speeds ranging from 3 meters/minute to 5 meters/se ...

s).

The mudflow threat

Much of downtown

is built on the

alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to Semi-arid climate, semiar ...

of the Small Almaty, at the point where the river leaves the steep and narrow Medeu Valley for the wider plain. The river valley, steeply descending to the city from the

Trans-Ili Alatau Ile Alatau (, ''Іле Алатауы''), also spelt as Trans-Ili Alatau, is a part of the Northern Tian Shan mountain system (ancient Mount Imeon) in Kazakhstan and Kyrgyzstan. It is the northernmost mountain range of Tian Shan, stretching for ...

mountains, is highly susceptible to the formation of debris flows and/or mudflows. During the 20th century, five catastrophic debris/mudflows happened in the valleys of the Small Almaty or its sister river (further west), the Big Almaty. The most severe of them was the catastrophic mudflow of 1921 in the Small Almaty valley, triggered by heavy rainfall. It killed 500 people out of Almaty's 45,000 population at the time, and destroyed much of the city. The total volume of that flow is thought to have been 10 million cubic meters (including some 3 million cubic meters of hard material, i.e. rock), coming down to the city at the discharge rate of 900 cubic meters per second. It is estimated that if a repetition of the 1921 mudflow were to strike the city in the early 21st century, the damage would be on the order of US $100 million. To prevent mudflows from reaching the city, a number of facilities have been built upstream of the city on both the Bolshaya (Greater) and Malaya (Lesser) Almatinka Rivers.

Dam history

The Medeu Dam blocks the Medeu Valley (the valley of the Malaya Almatinka River) just south (upstream) of the

Medeu The Medeu (, ''Medeu'') is an outdoor speed skating and bandy rink. It is located in a mountain valley ( Medeu Valley, or the valley of Malaya Almatinka River) on the south-eastern outskirts of Almaty, Kazakhstan. Medeu sits 1,691 metres above ...

Skating Rink. It was created on October 21, 1966 by a series of four preliminary explosions of 1,800 tons total and a final explosion of 3600 tons of

ammonium nitrate Ammonium nitrate is a chemical compound with the formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, but does not form hydrates. It is predominantly us ...

-based explosive. On April 14, 1967 the dam was reinforced by an explosion of 3900 tons of ammonium nitrate-based explosive. More filling was done later on, until the dam reached its design profile in 1972.

Mikhail Lavrentyev Mikhail Alekseyevich Lavrentyev (or Lavrentiev, ; November 19, 1900 – October 15, 1980) was a Soviet mathematician and hydrodynamicist. Early years Lavrentyev was born in Kazan, where his father was an instructor at a college (he later became ...

, the

Siberian Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states si ...

mathematician known for his work on the theory of "directed explosion", was among the scientific consultants of this construction-by-explosion project.Science in Siberia
No. 47 (2283), December 2000 It turned out that the dam was completed just in time for the potentially catastrophic mudflow of July 15, 1973. The dam worked, successfully stopping the flow. 3.8 million cubic meters of sediment was captured in the reservoir above the dam, bringing its bottom to the elevation of 1835 meters above the sea level. There is an unfinished dam further up in the valley at . This dam was proved unnecessary due to the success of the Medeu dam and was abandoned due to cost constraints. It is currently the site of a meteorological station.

References

External links

* {{coord, 43.150566, 77.062612, display=t, type:landmark Buildings and structures in Almaty Dams in Kazakhstan Flood control projects Buildings and structures built in the Soviet Union 1966 establishments in the Soviet Union Dams completed in 1972

The mudflow threat

Dam history

Further reading

References

External links