Yesterday, a group of residents of Krymsk whose houses had been affected by the flooding gathered close to the city administration's building, demanding payment of the promised compensation for their houses and for them to be provided with new ones. At the same time, while people are more concerned about the elimination of the consequences of the flooding, experts are in search of the causes of the tragedy.
According to Roman Vilfand, the director of RosHydroMet, "since July 4, a front called a “barometric depression” dominated in the north-east of the Black Sea. When the pressure is low, as a rule, there are upward currents in a zone of barometric depression. Dangerous summer events are 99% related to the so-called explosive convection processes, that is, to a fast vertical movment from the underlying layers on the surface of the sea or the land surface to the upper layers, to moist and warm air masses. This is the first point.
The second point is that since July 5, at an altitude of about 3-4 km in the north-east of the Black Sea, a micro-front formed which caused cooling in this layer. Naturally, such a lapse rate, when the sea surface was warm and at an altitude of 3-4 km, the air is cold, increasing the vertical currents. There was also quite large difference in horizontal temperatures - at a distance of 10 km from the coast the sea temperature was 20 C, and by the continent it was about 32-33 C. Such a large horizontal temperature gradient causes turbulence, which, in the end, according to the laws of dynamics, contributes to the rapid movement of air masses.
We are talking about the Caucasus, mountains, when the air flow does not just move as it would be, let us say, in the center of European Russia; they "bounce" against the slopes of the mountains and the foothills, and there is an additional vertical air rise. All these factors became the reason for the explosion process and the unprecedented intensive rains.
According to our measurements at the stations, the rainfall in less than a day was characterized by the following numbers: in Gelendzhik there was 300 mm, in Novorossiysk there was 300 mm, near Krymsk there was 170 mm, and at a small distance from it, in Dzhubga and Anapa, there was only 6-18 mm. This is a local, explosive and very intense process.
The aerography and the topography caused the catastrophe near Krymsk, because it is located in the valley between two mountain slopes. And very heavy rain was almost not absorbed into the soil, because it was full of moisture, and the rain fell into the channels of small and medium-sized streams. This led to resonance phenomena as a result of the confluence of several streams. The water level rose, and the subsequent events were simply disastrous.
Now the situation in the region where the emergency situation occurred is relatively stable; we expect some intermittent rain that is typical for the summer weather norm. It will not cause any catastrophic consequences, though, of course, every rain hampers recovery and rescue operations, which are now being carried out."
Marina Seliverstova, head of the Federal Water Resources Agency, criticized the version of the alleged influence of reservoirs located in the area of emergency: "Our inter-agency operational group, which consists of the representatives of federal executive bodies, organizations engaged in the operation of hydraulic structures and other interested bodies, excluded it at once. On July 7 we excluded this possibility by careful surveys of all hydraulic structures. In the 18 hours in Krymsk a meeting of an interdepartmental task force on regulating reservoirs in the Krasnodar Territory was held under my chairmanship. The inter-agency operational group immediately ruled out the possibility of the influence of the Neberdjayevskoye and Varnavenskoye reservoirs.
As for the Neberdjayevskoye reservoir, it reaches 176 meters; at the time of the emergency it was at the level of the "dead volume" – 176 meters. In the period of intense heavy rains the volume of the reservoir level reached 182 meters according to the Baltic system, that is, the presence of free accumulating capacity of the Neberdjayevskoye reservoir allowed the accumulation of 8 million m3 of water in this reservoir. This fact greatly eased the passage of the extreme floods in the city of Krymsk. That is, the reservoir has fulfilled its function of accumulating floods thanks to its accumulating capacity.
Concerning the Varnavenskoye reservoir, it is included in the system of reservoirs of the Kuban water system; it is a cascade reservoir. It reaches 10 m, according to the Baltic system, that is, it is much lower than the location of the city of Krymsk (25-30 m). At the time of the passage of flood the Varnavenskoe reservoir also had some usable capacity. Moreover, the River Adagum, which runs through the city of Krymsk, flows into the Varnavenskoe reservoir. That is, the Varnavenskoe reservoir could have influenced the situation if, firstly, it had been higher than 10 meters, and secondly, if the River Adagum had flowed backwards. But it is clear that these are physically impossible processes, so the inter-agency operational group immediately eliminated all of these circumstances.
The main regulatory capacity of the cascade in the North Caucasus is the Krasnodarskoye reservoir, operated by our agency, i. e. by the Federal government agency. The reservoir is in good order. There was a stock of usable capacity, and it was used. Besides, there are reservoirs in such systems as Shapsugskoye, Fyodorovskoye, Kryukovskoye and Varnavenskoye that are in the service of the Ministry of Agriculture, because these reservoirs are used for meliorative purposes. All of them have some usable capacity, and they have softened the consequences of the catastrophic flood becoming the receivers of flood waters during this emergency event."
Polad Polad-Zade, Former Deputy Minister of Water Construction of the USSR, called the event "an extraordinary phenomenon of precipitation that fell in a very short period above mountainous terrain. There was a stream that passed under a large bias. As a professional, I was very worried during these days; I was concerned about the lack of professionalism, the lack of responsibility for the description of this phenomenon. For example, somebody says on TV: "Yes, we found that there was not much drainage, there were only small portions." My God, is it possible to drain anything with a remote dam which has a shaft spillway? This dam detained a large part of the river flow of the River Neberdzhayka. And when it came to the level of the shaft spillway, there was not any drainage. It was impossible to drain anything. In the Soviet Union it was strictly forbidden to build anything in the valley, it was impossible. Today, the whole valley is full of buildings. In the 1990s, these areas were distributed and all the valley was built up. I am absolutely sure that all the people should be immediately evicted from there, from the floodplain. I'm not talking about the city with a population of 60,000 people, but the part of the city located in the floodplain should be evacuated; it is clear that such things can repeat themselves. The climate is changing, and such events will occur again.
