“We should have taken this factor into account in mid-March” – Kommersant
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A combination of factors led to the emergency situation in Orsk – high snow reserves, severe soil freezing and very high humidity against the backdrop of abnormal heat and rain. However, it was known that natural conditions would develop in this way back in March – the forecast of inflow into the Iriklinskoye reservoir gave up to 300% of the annual norm. Doctor of Geographical Sciences, Head of the Department of Land Hydrology of the Faculty of Geography, Moscow State University, told Kommersant about this. M. V. Lomonosova Natalya Frolova.
— According to the governor of the Orenburg region Denis Pasler, the current flood is a record in the history of observations in the region. Is it true?
— Indeed, the event is quite rare. The data indicate a significant excess of the long-term average values. Orsk is located below the Iriklinsky reservoir, that is, after 1966, when it was filled, water levels, in principle, could not be very high – after all, the reservoir regulates river flow. In part, the reservoir is created in order to mitigate the consequences of such floods. But despite this, and perhaps partly thanks to discharges from it, the flood in the Orsk region turned out to be very high.
— What role did the reservoir play in the emergency?
— The reservoir accumulates water in the spring during the flood, but due to the large influx this year and the high level at the start of the flood, quite a lot of water had to be released.
— What factors, besides this, led to the emergency?
“The most curious thing is that everyone was well aware of the likelihood of this situation. A document is posted on the Roshydromet website (it can also be found on the website of the Hydrometeorological Center of Russia) – a certificate about the expected nature of the spring flood in 2024 on the rivers of the Russian Federation and a preliminary forecast of water inflow into large reservoirs in the second quarter. It was released on March 10th. The certificate states that abnormally high snow reserves are observed in the Ural basin – more than 120% of average values. In addition, in the Ural basin there is very strong soil freezing, reaching 100 cm or more, which is not typical for the rest of the European part of Russia. In addition, this year there is very high soil moisture. All these three factors together led to the fact that, against the backdrop of abnormally warm weather and heavy rains during snowmelt, melt water did not go into the soil, but simply flowed down the surface. Everything fell into the channel network. This happens quite rarely, but this is how nature ordered it this year.
And the second point is the peculiarities of reservoir regulation. The forecast for the inflow into the reservoir was up to 300% of normal! Obviously, it was necessary to take this factor into account in mid-March.
— Can we say that the situation was also influenced by climate processes, for example, global warming?
— The latest data on the impact of climate change on the water regime of rivers in the European part of Russia indicate that on most rivers, flood maximums, on the contrary, are decreasing: it becomes low, and on many rivers it is barely noticeable. This is due to warmer winters and frequent thaws, during which the snow cover melts. But natural processes are more complex; the course of the flood is also determined by the current synoptic situation. And this year’s disaster in the Urals is also due to the human factor.
— Can you name situations similar to what is happening now in the Urals?
— Floods periodically occur in one region or another. Not far away in the Ishim basin, in the Tobol basin there are often floods in the spring. Prolonged heavy rains caused catastrophic flooding in the Irkutsk region in 2019. Floods occur in the north, where ice jams are a common cause. Veliky Ustyug, Lensk, Yakutsk, Tomsk and other cities suffer from this type of natural disaster. One can recall the flood in the Amur basin in 2013, again due to prolonged rainfall during the monsoon. That is, the reasons may be different, but the disasters are comparable.
— According to your forecasts, when will the water go away?
– This could last a month or a month and a half. The decline of the flood is much less rapid than the rise. How soon the soil dries out will be determined by weather conditions.
— How long can it take in good weather for buildings that are under water to dry out?
– This will take months. Of course, people will not be able to be compensated for the resulting damage and repair costs, so the consequences will be felt for many, many months and even years.
— What are the other consequences of floods for infrastructure that are not as obvious as damage to houses?
— We will have to build dams again, strengthen the embankments, we will have to clean the river bed. In addition, river water is used in various sectors of the economy; its quality may be unsatisfactory. If winter crops were planted, they will die.
— Are the consequences of the flood for the ecosystem as a whole noticeable?
— Flood in our natural area is a natural process to which both aquatic organisms and ecosystems on floodplains have adapted. On the contrary, when the floodplain does not flood, this is often a problem. The floodplain is fertile because the water leaves its nutrients there. Nature will quickly cope with the negative consequences of such disasters, but it will be much more difficult for humans.
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