The construction of Dams in Central Asia is complicated by tectonic faults
In Central Asia, the number of power plants that do not saturate the atmosphere with carbon dioxide emissions is growing – solar, wind and hydroelectric power plants. Engineering surveys have begun in the area of the future nuclear power plant (NPP) in Kazakhstan. Kyrgyzstan has decided on the choice of the general contractor of the NPP. Completion of the large Rogun Dam is underway in Tajikistan.
For 35 years, structures have already been erected in the region that are not ashamed to show. Several “largest” objects have appeared in Tajikistan – the tallest flag, the largest teahouse “Melon”, the world’s tallest stone-earth dam is being built. Nevertheless, the record of the high flag did not last long, the Melon teahouse did not become more popular than the recently demolished Rohat teahouse, and it was put up for auction.
As for the dam in Rogun, the option of reducing its height and, as a result, reducing the volume of the reservoir and the capacity of the Dam is not excluded. And it’s not that environmentalists of the Rivers Without Borders organization opposed this Dam, but Uzbekistan protested even earlier. The fact is that the hydroelectric power plant is being built according to the project of the 70s of the XX century on the Ionakh tectonic fault and there is a powerful layer of salt under the dam. There are quite a lot of other dangerous tectonic faults in Central Asia, as well as around the world.
The most famous fault of the earth’s crust is the rift zone of Lake Baikal. The middle of the 1500 km long tectonic fault is filled with lake water, and the rift itself is located at the junction of the Eurasian and Amur plates. There are no such large tectonic faults in Central Asia, but the region is located on the border of the Eurasian and Indian plates, and enormous energy accumulates in the Tien Shan and Pamir mountains. The scale of the released energy is indicated by the famous Tulip mountain in Tajikistan with a height of more than 1 km, where rocks in the past millennia have been twisted into an arc. Scientists are concerned about the Talaso-Fergana tectonic fault zone, where earthquake epicenters lie at a depth of up to 50 km.
There is no need to go far for examples of catastrophic earthquakes. Ashgabat was destroyed in 1949. In the same year, the village of Khayit in Tajikistan was destroyed 200 km from the Rogun Dam – the force of the shock at the epicenter was such that the mountains closed from two sides at a speed of about 100 km/h. In 1966, Tashkent suffered, and in February 2023, a major earthquake occurred in Turkey at the intersection of the African, Anatolian and Arabian tectonic plates, in which more than 50 thousand people died.
Today they also remember the Sichuan earthquake in China in 2008. Earth tremors of 7.9 points were felt even in the central cities of China, India and Russia, and the death toll exceeded 80 thousand people. Scientists have established a rupture of the Wenchuan tectonic fault with a length of 300 km with displacements of several meters. As a result, a 156 m high dam was damaged, and the water threatened to flood the city of Dujianian, where 500 thousand people lived, so the reservoir was emptied to repair the dam. A number of seismologists believe that the tremors could be the result of enormous water pressure on the fault near the epicenter. According to some reports, the chief engineer of the Sichuan Bureau of Geology and Minerals, Fan Xiao, believed that in the two years that had elapsed from the beginning of filling the reservoir to the disaster, water had entered deep into the fault. Chinese geophysicist Lei Xingling also believes that the water in the reservoir could lead to seismic tremors in the fault area.
The conclusion that Chinese geomorphologists made from the tragedy indicated that the cause of the tremors was a sharp increase in rock stress. Having learned from experience, the Chinese are monitoring the condition of their dams, and China, Russia and Uzbekistan refrain from financing the Rogun Dam. But the depth of water in the Rogun reservoir is hundreds of meters, and the water pressure on the foundation will be enormous.
It is known that the construction of a dam with a height of 335 m is under the control of the Tajik authorities, and the Rogun Dam is considered the flagship of economic development. In the mid-80s of the XX century, the author of this article led a group of computer calculations of a breakthrough wave from Lake Sarez with a volume of 17 cubic km in the Pamirs and does not intend to frighten anyone. But if the dam of the Rogun Dam standing on the Ionakh tectonic fault collapses from an earthquake, a wave of a breakthrough up to two hundred meters high will rush along the Vakhsh, and this may happen during the lifetime of the current generation.
The catastrophe will be terrible, which has not yet happened. The wave of breakthrough will enter the Nurek reservoir, overflow over the dam and destroy the city of Nurek. A stream with a total volume of more than 10 cubic km will rush along the Vakhsh River. Sweeping away several Dams of the Vakhsh cascade on the way, the stream will go along the Amu Darya up to the former Aral Sea. The capital of Tajikistan will not be affected, but up to 7 million people will be in the flood zone (as in the Sarez Lake disaster), and neighboring countries and Russia will be covered by a wave of refugees. No one predicted the political consequences, but once again it does not hurt to remind about a possible catastrophe – the engineers who are building the dam should be aware of the responsibility.
In Central Asia, and especially in Tajikistan, they often talk about the high potential of Dams, but these conversations will subside. You can talk about it for a long time, but the potential is not new power plants, but only words. The admiration from the words “halva-halva” and from the failed construction of more than ten painted large Dams on the transboundary Panj River has almost stopped. And it stopped not because the sides of the dams rest on the shores of two different countries, but because a wave of breakthrough from Lake Sarez can pass along the Panj River – it will destroy all living things. And if the threat of a lake breakthrough is excluded by lowering the water horizon, the flow can come from any other earthquake-prone area of the Pamirs.
The world is building “clean”, carbon-free nuclear power plants, and today there are more than 440 nuclear reactors, but there are none in Central Asia yet. The World Bank’s examination of the Rogun Dam project concluded that the project is technically feasible. However, experts write that in order for the project to pay off, the country will have to sell 70% of electricity, the dividend payment period for the purchased shares has not been named, and the issue of the height of the dam still bothers people. There is practically no experience of building on a tectonic fault. Few people know about the convergence (convergence of walls) of the machine room of the Rogun Dam. The journal “Fundamental and Applied Issues of Mining Sciences” wrote in 2020: “… the process of convergence of the lateral surfaces in the gates of the engine room at the end of 2018 is of a non-extinguishing nature,” therefore, the margin of safety (if any), apparently, it would not be superfluous to calculate additionally.
The information in the article is given to draw attention to the problem. Where it comes to the technical side of the matter, decisions should be made not by the “highest” officials, but by specialists. In 1986, high officials from the Politburo of the CPSU Central Committee, supported by writers and Literaturnaya Gazeta, closed the project of transferring part of the Ob River to Central Asia and the Aral Sea. They did not think about the future there, and as a result, the Aral Sea almost died, and Russia’s influence on Central Asia weakened. Therefore, after conferences, forums and symposiums on glaciers, investments and livestock, it will not hurt to hold an international conference on threats to Dams from tectonic faults.
Andrey Grabatov (Nezavisimaya Gazeta)
Original (in Russian): Строительство ГЭС в Центральной Азии осложнено тектоническими разломами
