Neva
Floods

Floods in St. Petersburg are usually caused by the overflow of the delta of Neva and by surging water in the eastern part of Neva Bay. They are registered when the water rises above 160 centimetres (63 in) with respect to a gauge at the Mining Institute. More than 300 floods occurred after the city was founded in 1703. Three of them were catastrophic: on 7 November 1824, when water rose to 421 centimetres (166 in); on 23 September 1924 when it reached 369 centimetres (145 in), and 10 September 1777 when it rose to 321 centimetres (126 in). However, a much larger flood of 760 centimetres (300 in) was described in 1691.

Besides flooding as a result of tidal waves, in 1903, 1921 and 1956 floods were caused by the melting of snow.
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