It is partially possible to control the water level. The dam of the Irkutsk hydropower plant allows to control the water level on the segment of the former Angara riverbed from Listvyanka to Irkutsk, which is the “real” Irkutsk water reservoir. Some authors believe that the entire Baikal is the water reservoir of the Irkutsk hydroelectric power plant. But this is a controversial statement, at least because the lake was not created during the construction of the dam, but formed millions of years earlier. In addition, as recent years have shown, the level of the lake water is much more dependent on the inflow than on the capacity volume.
At the end of 2014 it became clear that the Baikal region was experiencing the beginning of the most serious phase of yet another period of low water. The water that passed through the units of the Irkutsk HPP fell to 1,250 cubic meters per second and has been equal to an average of 1,300 cubic meters per second since then until today. There were only a few hours when the consumption was increased on the command of the controllers of the United Energy System of Siberia, so that to compensate for accidents at other energy sources.
Why this was useful: at an average flow rate of 1,300 cubic meters per second, 40.9 billion cubic meters or 40.9 cubic kilometers of water passed through the main power plant during a year. The natural flow through Angara before the construction of the HPP amounted to 60-61 cubic kilometers per year. So, the dam in Irkutsk made it possible to save 20 cubic kilometers of water in the lake each year. Otherwise, the water level would fall uncontrollably. What dangers could this bring? Let’s remember the history: before the construction of a hydroelectric power plant winter floods in Irkutsk were regular. The water in Angara itself always froze, but the water at its source almost never froze, because it came from deeper and warmer layers of the lake. One of the most dangerous floods occurred in 1952, when the entire city centre was flooded at a temperature of minus 40 Celsius. The regulation of the level of the Irkutsk water reservoir with the help of the hydropower plant saved the city from such serious problems.
1300 cubic meters per second is the so-called “public health” capacity, the minimum flow rate through the dam; the rate should not fall below this level, otherwise the water supply of the consumers downstream the river with the water of decent quality will be threatened. These consumers are hundreds of thousands of residents of Angarsk and beyond. Sometimes you can hear that the problems with guaranteed water supply to the population in the lower pool may be exaggerated. The say that water withdrawal may be increased on request and upon necessary investments, then the Irkutsk HPP may be able to pass even a smaller amount of water. Indeed, once the “public health” level made up 1050 cubic meters per second. But over the years of the dam exploitation the level had to be increased: first of all, the bottom of Angara downstream to the hydroelectric power plant subsided due to large-scale mining of sand and gravel in the riverbed for their use in the production of building materials and road construction. It is not totally impossible that the current level of “public health” level will have to be increased.
Answering the most common question: why fluctuations in the water level influence the lake ecology and could it be harmful to Baikal.
In 1976 the regional game manager Ivan Sizov established the Snezhinskiy State Game Reserve on the territory of Zakamensky District.
We continue to keep you informed about the fluctuations in the level of Lake Baikal and why this is important.
We had a talk with the young scientist Daria Bedulina about how Baikal endemics make it possible to assess the state of the lake now and in the future.