As usual, any shock near Sarez immediately causes a wave of concern —what if it breaks through? Should we be afraid of such a catastrophe? Experts are divided: some believe that this is impossible, others are sounding the alarm and proposing ways to solve the problem.
Sarez Lake is located in the Murghab region of Tajikistan, its length is — about 70 km, maximum measured depth is — about 500 m, water volume is — more than 17 cubic meters. km.
Fears regarding a possible breakthrough of Lake Sarez as a result of an earthquake are groundless, says Sobit Negmatullaev, head of the Geophysical Service of the Academy of Sciences of Tajikistan.
The scientist notes that some experts talk about the threat of a breakthrough of the Usoi Dam (the dam of Lake Sarez) as a result of destructive tremors, which could lead to great destruction in Tajikistan, Afghanistan, as well as Uzbekistan and Turkmenistan.
According to Negmatullaev, these fears are absolutely groundless. He noted that the territory of Lake Sarez is under constant supervision of specialists, and there is no reason for concern.
The former head of the Committee for Emergency Situations and Civil Defense, Rustam Nazarzoda, said the same thing. He noted that the lake is under constant supervision of Tajik specialists.
«Sleep well. There are no major changes observed on Sarez», — Nazarzoda emphasized.
According to him, a modern early warning system was installed near Lake Sarez, a system for monitoring all changes that occur in the area of the lake, including at its bottom.
6 million are at risk
Meanwhile, some researchers believe that the lake still poses a danger — not only to nearby settlements, but also to the entire region. There is a hypothesis that in the event of a breakthrough, a huge mass of water will pass through the mudflow almost to the Aral Sea.
…More than 30 years ago, a group of specialists developed a mathematical model using the most modern computers in those years. But as soon as scientists received the first results of modeling the disaster, these results were immediately classified. They were made public only in 2001, and even then not completely.
According to the model, approximately 6 million people live in the area of possible flooding in Tajikistan, Uzbekistan, Afghanistan, Turkmenistan and Kazakhstan. In the lower reaches of the Amu Darya, the water level from the breakthrough will rise slowly, from several hours to 3-4 days. But in the Pamirs and the Panj Valley this will be a disaster.
According to scientists, a mud-stone flow with an initial height of approximately 80 m and a speed of about 100 km/h will pass through the mountain gorge. The flow will demolish not only homes, but also bridges and many hydraulic structures on Pyanj, flood cemeteries, cattle burial grounds, and minefields left over from the war in Afghanistan and Tajikistan.
A huge number of victims, injured and died from diseases caused by flooding are predicted. There will be at least a hundred thousand of them.
Experts are concerned
Three years ago, at a round table dedicated to Sarez issues, Doctor of Technical Sciences Yuri Sevenard —, a Soviet and Russian hydraulic builder who in the 60-80s of the last century led the Nurek hydroelectric power station, and was also involved in the construction of a complex of flood protection structures in Leningrad, spoke on this issue.
Alexander Ryabikin — Soviet and Russian hydraulic builder, among other things — former head of construction of hydroelectric power stations «Sangtuda-1» in Tajikistan, candidate of technical sciences, as well as Andrey Zakhvatov — in 1975-1990s — hydraulic engineer of the design institute «Tajikgiprovodkhoz», and in 1986-1989, head of the group for mathematical modeling of the consequences of a possible disaster from the destruction of the Usoi blockage of Lake Sarez.
Experts raise the question of the possible presence of ice (firn) inclusions in the body of the dam, given the fact that the landslide (during the formation of the Usoi blockage) occurred in winter, and at this time of year the thickness of the snow cover in these places reaches several meters.
Why is this so important?
According to them, the ice in the body of the rubble is covered with soil and coarse materials, but the water gradually erodes it, and soil subsidence occurs. And this is a very dangerous phenomenon, because in the event of an earthquake, the crest of the blockage (the dam of Lake Sarez) can sag sharply.
The uncertainty associated with the lack of data on the geological structure of the rubble and the volume of snow and ice in its body does not make it possible to make clear engineering decisions.
In general, experts are confident that the condition of the rubble is causing more and more concern every year. And the only solution that they see today and which will provide security guarantees for people living in the Pyanj and Amu Darya river basin is to lower the water level in the lake by 100-150 m below the existing level.
How to do this?
According to experts, in the 1980s, engineers studied the issue of lowering the water level in Sarez.
And the first stage of the complex of hydraulic engineering works on Sarez, in theory, should be work to bring the lake into a safe state. To do this, you need to lower the water horizon by about 100, or better yet — by 150 m due to filtration through the body of the blockage. And in order to stop the main flow of water into the lake during a drop in water level, it is necessary to divert the Murghab River into the Kakuibey River through a 30-kilometer tunnel, intercepting its bed with a dam in the area where the river flows into the lake.
In addition, it is necessary to use the lowland located below the Usoi blockage on the Bartang River. According to experts, it will be able to absorb almost the entire volume of the catastrophic flood if the blockage breaks.
There it will only be necessary to build — about 60 km below the rubble — a mudflow-proof dam. This will be a kind of trap to intercept a possible catastrophic wave of breakthrough from the lake. The upper pool of this dam should be capable of receiving about 7 cubic meters. km of water. A hydroelectric power station can be built in its downstream.
Thus, according to experts, it will be possible to protect 6 million people.
At the same time, experts note that lowering the water in the lake is a priority measure, but not the only one. Along with this, it will be necessary to build a hydroelectric power station in the downstream of the Usoi dam, which will generate electricity by passing Sarez water through its turbines.
Experts believe that after carrying out anti-filtration measures, the useful volume of the reservoir into which the lake will turn will be quite significant — 7-8 billion cubic meters. And this is almost twice as much as at the Nurek hydroelectric power station!
Experts urge the authorities not to take lightly the threat of a breakthrough in Lake Sarez. Moreover, not only the authorities of Tajikistan should be concerned about this problem. And the republic simply cannot begin work to prevent a catastrophe alone. In their opinion, it is necessary to involve neighboring states. No matter how expensive it is to prevent danger, it will cost us many times less to eliminate the consequences of a possible disaster.
Sputnik Tajikistan
