Location description and effect of the proximity to the Baltic Sea
The city, originally built in a marshy area, lies at the mouth of the Neva into the Gulf of Finland. The city area covers about 1,431 km² including the suburbs such as Peterhof and Pushkin, which have administratively belonged to Saint Petersburg since 1999, of which about 10 percent is water. The city consists of 42 islands. Originally there were more, but numerous canals between them have since been filled in. The city itself had to be built two to four meters above sea level. This is because the mouth of the Neva River is roughly at sea level, and the first builders encountered groundwater at a depth of just a few centimetres. The banks were fortified with granite blocks early on, which not only protects Saint Petersburg from the water, but contributes a lot to the specific cityscape. Alexander Pushkin described it as: "The city dresses in granite".
Due to its location a few meters above sea level, the city is always threatened by floods. Kronstadt, located on a nearby island, is a reference point for the sea level gauge. The reference area of this Kronstadt gauge is about 15 centimetres higher than the Amsterdam gauge valid in Germany and is a reference point for altitude in large parts of Eastern Europe and was in the New Federal States until 1993. The city has often been a victim of flooding. Official statistics count 295 floods since the city was founded (as of 2003), 44 of them since 1980 alone. The worst floods were in 1824 (200 to 500 deaths, depending on the statistics) and 1924.
Climate
Saint Petersburg lies on the same latitude as the cities of Oslo and Stockholm, the southern part of Alaska and the southern tip of Greenland. It has a typical maritime climate, the weather is changeable and can change within a short time. Summers are comparatively mild with average temperatures of 19 to 22 °C, but in winter average temperatures drop to -4 to -8 °C. The maxima are +37 °C in summer (2010) and -42 °C in winter (1941 and other, though uncertain, data). Due to its location, it does not get completely dark at night at the time of the summer solstice (so-called "white nights").
Monthly average temperatures and precipitation for St. Petersburg | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | | | | Max. Temperature (°C) | −5,1 | −4,1 | 1,1 | 8,1 | 15,6 | 20,1 | 21,9 | 20,0 | 14,5 | 8,2 | 2,0 | −2,3 | Ø | 8,4 | | Min. temperature (°C) | −10,7 | −9,7 | −5,2 | 0,6 | 6,5 | 11,4 | 13,9 | 12,8 | 8,1 | 3,4 | −1,9 | −7,1 | Ø | 1,9 | | | Precipitation (mm) | 38 | 31 | 35 | 33 | 38 | 58 | 80 | 81 | 69 | 67 | 56 | 51 | | 637 | | | Sunshine hours (h/d) | 0,7 | 1,9 | 4,0 | 6,0 | 8,4 | 9,2 | 8,6 | 6,9 | 4,3 | 2,3 | 0,9 | 0,4 | Ø | 4,5 | | | Rainy days (d) | 10 | 9 | 9 | 7 | 7 | 9 | 10 | 11 | 12 | 12 | 12 | 12 | | 120 | | | Water temperature (°C) | 1 | 0 | 0 | 1 | 5 | 12 | 17 | 16 | 12 | 8 | 5 | 2 | Ø | 6,6 | | | Humidity (%) | 85 | 83 | 78 | 71 | 64 | 67 | 72 | 77 | 81 | 83 | 86 | 87 | Ø | 77,8 | | Temperature | | | | | | | | | | | | | | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | | Precipitation | 38 | 31 | 35 | 33 | 38 | 58 | 80 | 81 | 69 | 67 | 56 | 51 | | | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Source: Roshydromet, wetterkontor.de |
Effect of the Neva
With a length of 74 kilometres, the Neva is a very short river, but one of the most water-rich rivers in Europe. It gets up to 600 meters wide and has a strong current. The river covers about 28 kilometres of its route within the city area of Saint Petersburg.
Until the 19th century, the biology of the relatively shallow bay of the Neva alone was sufficient to clean the wastewater from Saint Petersburg. Even today, the wastewater from the industrial city of 5 million inhabitants accounts for only 2 percent of the total volume of water in the Neva. In the mid-19th century, however, the first waterborne epidemics, such as cholera and typhoid fever, broke out. During the typhus epidemic of 1908 alone, about 9000 people died. A change in the conditions of discharge helped to alleviate the problem for the time being from 1910 onwards. In the 1950s and 1960s, the sharp increase in population caused the sewage problem to escalate again. This was compounded by the increased pollution of the Neva River along its course - it drains Lake Ladoga, on the shores of which are numerous factories and which itself receives the dirty water of numerous Russian cities via its tributaries. A sewage treatment plant has been built, but 25 to 30 percent of urban wastewater still reaches the river and the bay untreated. The bay is home to mainly freshwater but also some brackish water inhabitants. The biological system is highly variable and suffers from human interference. Together with Moscow, Petersburg is considered one of the most polluted cities in Russia.
Since 1978, the Soviet government has had the Petersburg Dam built across the Neva Bay to protect the city from flooding. Unlike most river floods, the floods on the Neva are not caused by the river bringing more water from its upper reaches, but by westerly winds pushing into the Gulf of Finland and preventing the water from flowing away or, in extreme cases, reversing the direction of flow.
The construction was temporarily demolished in the late 1980s for environmental reasons: The dam disrupted the circulation of coastal water, large parts of the water stood still, and water quality dropped significantly. Fears were that the entire bay could turn into a swamp. However, the dam has continued to be built since 1990 with Dutch aid and support from the European Investment Bank and was completed in 2010. However, as the environmental arguments against the dam remain, the issue remains very controversial in the city.