Floods of St. Petersburg. In what their feature?
the Tsar Pyotr enjoined to build the new capital of the state Russian in very unsuccessful place. The place in the delta of the Neva River not only is blown by all winds from the Gulf of Finland, but also is waterlogged. In the fall strong western winds at which quite often there are floods are very frequent. began
of the Flood in the 18th century when water rose on half-meter, in XIX - when water was above a normal level on meter, at the beginning of the 20th century - at rise from one and a half meters, presently - when water level exceeds normal level level on 2. 5th meter.
If to consider that on half-meter - meter water rises nearly an every fall, it is possible to understand, life of Petersburgers in the past was how difficult. Soon after the basis of St. Petersburg, only 3 months later, in the night of August 20, 1703, there was the first St. Petersburg flood, water rose more than by 2 meters.
Long enough was considered that the flood reason in St. Petersburg - the western wind which is “locking“ Neva and not allowing it to follow to the gulf. Here supposedly Neva also rises as wind does not leak... But at the same time water level would rise for hours, and actually at severe floods water level rises VERY quickly. Eyewitnesses of a flood of 1924 told that water level rose so quickly that water was poured through granite parapets, flooding Vasilyevsky Island, and the eyewitnesses of this show trying to escape from a flood were forced to run in the closest entrance of the house soon enough and to walk upstairs to leave from water. Wind of it not to reach.
According to opinion of scientists, the level of a flood depends on two factors - from wind and from a wind-induced wave from the Gulf of Finland.
Strong western wind as if “locks“ Neva in its delta, preventing it to follow to Markizova a pool. And the wind-induced wave created by the cyclone which is going east across the Gulf of Finland from the West, coming to small part of the Gulf of Finland, sharply increases in height - and strongly increases water level including in Neva.
It is theoretically calculated that wind can overtake for increase of water level to 4 meters, and a wind-induced wave - to 5 meters so (theoretically), before creation of a complex of constructions on protection of the city against floods it was possible to expect a flood with rising of water in 9 meters.
The city protected the created complex of dams, bridges and locks so it is not necessary to wait for higher than 4 meters of a flood from a wind-induced wave. Moreover, there were already several potentially dangerous situations when floods during which locks were closed were possible - and floods managed to be avoided. Locks block only at several o`clock, during this time Neva cannot overflow Markizova a pool.
If the situation with a flood “from wind“ was not learned to be predicted yet, then the wind-induced wave moving on the gulf together with a cyclone can be easily in advance defined. Only at a depth it is much more less expressed. But when on one of points of supervision in the Gulf of Finland in front of Kronstadt devices note rise in water level, it means threat of a flood and need to close locks of protective constructions. Speed of the movement of a wave is equal to cyclone movement speed, and seldom it happens quicker, than 50 km/h so time to react to threat in Kronstadt is.
Even in the presence of the constructions protecting the city from a wind-induced wave today still in the downtown cellars are not reliable places for storage something valuable or for accommodation.
For the inhabitants of St. Petersburg who are not knowing the dangerous party of floods from own experience (1824, 1924, several more - the biggest), they turned into a peculiar attraction long ago. At rising of water approximately to 2 meters very impressive types happen in the downtown, on Fontanka Embankment near Sennaya Square, on Karpovki River Embankment that on the Petrograd party, near the Petrograd subway and, is told, on the Krestovsky island (itself there never happened at this time, but shootings for TV - reportings of the cars and trucks going at floods on water do on Krestovsky).
... Yes, absolutely forgot about the Peter and Paul Fortress (when water floods beaches and approaches the walls, and the people with squeal run from the Hare island on the Petrograd party on the semi-flooded bridges) and about spit of Vasilevsky Island - from there all magnificence of elements is perfectly visible, and to escape too to eat where.