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The average width along the river is 400 to 600 metres (1,300 to 2,000 ft).
Its water level began to rise, eventually flooded the valley of Mga and broke into the valley of the river Tosna.
The Ivanovo rapids of the modern Neva were created in the breakthrough area.
The hydrological network had been altered by the development of St. When it was founded in 1703, the area was low and swampy and required construction of canals and ponds for drainage.
The earth excavated during their construction was used to raise the city.
Then, the Tosna River was flowing in the modern bed of the Neva, from east to west into the Litorinal Sea.
The river banks are low and steep, on average about 3 to 6 metres (10 to 20 ft) and 2 to 3 metres (7 to 10 ft) at the mouth.
Despite its modest length of 74 kilometres (46 mi), it is the fourth largest river in Europe in terms of average discharge (after the Volga, the Danube and the Rhine).Because of the uniform water-flow from Lake Ladoga to the Neva over the whole year, there are almost no floods and corresponding water rise in the spring.The Neva freezes throughout from early December to early April.So about 2000 BC the Neva was created with its tributaries Tosna and Mga.According to some newer data, it happened at 1410–1250 BC making the Neva a rather young river.The average flow rate in the rapids is about 0.8–1.1 metres per second (2.6–3.6 ft/s).