Editing Neva (section)

==Description==
===History of the delta===
In the [[Paleozoic]], 300–400 million years ago, all the delta region was covered by a sea. Modern relief, eminences, were formed by glacial scouring. Its retreat formed the [[Littorina Sea]], the level of which was {{convert|7|to|9|m|ft|0}} higher than its successor the Baltic Sea. Then, the [[Tosna]] was flowing in the modern lower half of the Neva as today, into the Litorinal Sea. In the north of the [[Karelian Isthmus]], the sea was united by a wide strait with [[Lake Ladoga]]. The [[Mga (river)|Mga]] then flowed to the east, into Lake Ladoga, near the modern source of the Neva. Thus the Mga then was separate from the Tosna/lower-Neva basin.<ref>{{cite book|url=https://books.google.com/books?id=LElrclnl0C8C&pg=PA217|pages=217–219|title=Climate development and history of the North Atlantic realm|author=Wefer, Gerold|publisher=Springer|year=2002|isbn=3-540-43201-9|access-date=3 December 2021|archive-date=10 April 2023|archive-url=https://web.archive.org/web/20230410073933/https://books.google.com/books?id=LElrclnl0C8C&pg=PA217|url-status=live}}</ref>

Near the modern Lake Ladoga, by [[glacial rebound]] land rose faster, and an endorheic lake briefly formed. This overspilled, eventually the whole Mga valley and thus broke into the western valley (the valley of the Tosna/lower-Neva). The Ivanovo [[rapids]] of the modern Neva were created at the breakthrough. According to early books, the breakthrough may have been about 2000 BC, but according to more recent research, this happened at 1410–1250 BC, making the river rather young.<ref>{{cite journal|title=Shoreline displacement of Lake Ladoga — new data from Kilpolansaari|last1=Saarnisto |journal=Hydrobiologia|first1=Matti
|year=1996|last2=Grönlund|first2=Tuulikki|author8=Saarnisto, Matti and Grönlund, Tuulikki
|volume= 322| issue = 1–3|pages=205–215|doi= 10.1007/BF00031829|s2cid=42459564 }}</ref>

The valley is lined with glacial and post-glacial sediments and has changed little over 2,500 years.<ref name=Geogr>{{cite book|author = Darinskii, A.V.|title = География Ленинграда|trans-title = Geography of Leningrad|publisher = Lenizdat|year = 1982|pages = 12–18|url = https://books.google.com/books?id=KuRdPAAACAAJ|access-date = 3 December 2021|archive-date = 10 April 2023|archive-url = https://web.archive.org/web/20230410074002/https://books.google.com/books?id=KuRdPAAACAAJ|url-status = live}}</ref> The delta was formed at that time, technically a pseudodelta, as not from accumulation of river material but by scouring past sediments.<ref name=SPBe>St. Petersburg: Encyclopedia. – Moscow: Russian Political Encyclopedia. 2006; {{ISBN|5-8110-0107-X}}</ref>

===Topography and hydrography===
The Neva flows out of Lake Ladoga near [[Shlisselburg]], flows through Neva's lowlands and discharges into the [[Baltic Sea]] in the [[Gulf of Finland]]. It has a length of {{convert|74|km|mi}}, and the shortest distance from the source to the mouth is {{convert|45|km|mi}}. The river banks are low and steep, on average about {{convert|3|to|6|m|ft|0}} and {{convert|2|to|3|m|ft|0}} at the mouth. There are three sharp turns: the Ivanovskye rapids, at Nevsky Forest Park of the Ust-Slavyanka region (the so-called "Crooked Knee"), and near the [[Smolny Institute]], below the mouth of the river [[Okhta]].<ref name=SPBe /> The river declines {{convert|4.27|m|ft}} in elevation between source and mouth.<ref name="Neva2" /> At one point the river crosses a [[moraine]] ridge and forms the Ivanovskye rapids. There, at the beginning of the rapids, is the narrowest part of the river: {{convert|210|m|ft}}. The average flow rate in the rapids is about {{convert|0.8–1.1|m/s|ft/s}}. The average width along the river is {{convert|400|to|600|m|ft}}. The widest places, at {{convert|1000|to|1250|m|ft}}, are in the delta, near the gates of the marine trading port, at the end of the Ivanovskye rapids near the confluence of the river Tosna, and near the island Fabrinchny near the source. The average depth is {{convert|8|to|11|m|ft}}; the maximum of {{convert|24|m|ft}} is reached above the [[Liteyny Bridge]], and the minimum of {{convert|4.0|to|4.5|m|ft|0}} is in Ivanovskye rapids.<ref name=Geogr2>{{cite book |author = Darinskii, A.V. |title = География Ленинграда|trans-title= Geography of Leningrad |publisher = Lenizdat |year = 1982 |pages = 34–45}}</ref>

In the Neva basin, rainfall greatly exceeds evaporation; the latter accounts for only 37.7&nbsp;percent of the water consumption from the Neva and the remaining 62.3&nbsp;percent is water runoff.<ref name=a59>{{cite book |title = Ленинград. Историко-географический атлас|trans-title= Leningrad. Historical atlas|location = Moscow |publisher = Main Office of Geodesy and Cartography under the [[Council of Ministers (Soviet Union)|Council of Ministers of the USSR]] |year = 1981 |page = 59}}</ref> Since 1859, the largest volume of {{convert|116|km3|mi3|lk=out}} was observed in 1924 and the lowest in 1900 at {{convert|40.2|km3|mi3}}.<ref name =SPBe/> The average annual discharge is {{convert|78.9|km3|mi3}} or {{convert|2500|m3/s|cuft/s}} on average.<ref name="Neva2">{{cite book|author= Nezhihovsky, R.A.|url= https://books.google.com/books?id=SqcgAQAAMAAJ|trans-title= Neva River and Neva Bay|title= Река Нева и Невская губа|publisher= Gidrometeoizdat|year= 1981|access-date= 25 October 2015|archive-date= 10 April 2023|archive-url= https://web.archive.org/web/20230410073956/https://books.google.com/books?id=SqcgAQAAMAAJ|url-status= live}}</ref> Due to 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. The ice thickness is {{convert|0.3|to|0.4|m|ft|1}} within Saint Petersburg and {{convert|0.5|to|0.6|m|ft}} in other areas. Ice congestion may form in winter in the upper reaches of the river, this sometimes causes upstream floods. Of the total ice volume of Lake Ladoga, {{convert|10.6|km3|mi3}}, less than 5&nbsp;percent enters the Neva.<ref name=a59/> The average summer water temperature is {{convert|17|to|20|C|F}}, and the swimming season lasts only about 1.5 months. The water is fresh, with medium turbidity; the average salinity is 61.3&nbsp;mg/L and the [[calcium bicarbonate]] content is 7&nbsp;mg/L.<ref name=SPBe/>

{| Class = "wikitable"
|+ Average [[streamflow]]. Values in brackets are percentage of the annual values.<ref name=a59/>
! Quantity
! April to June <br />
! July to September <br />
! October to November <br />
! December to March <br />
! Total
|-
| Runoff, km<sup>3</sup>|| 22.7 (28.5%)|| 23.5 (29.4%)|| 14.1 (17.7%)|| 19.4 (24.4%)|| 79.7
|-
| Suspended sediment, [[Ton|kt]]|| 162 (31.7%)|| 136 (26.7%)|| 143 (28.0%)|| 69 (13.6%)|| 510
|-
| Bottom sediments, kt|| 26.5 (40.8%)|| 15.8 (24.3%)|| 21.3 (32.7%)|| 1.4 ( 2.2%)|| 65.0
|-
| Ions runoff, kt|| 735 (25.6%)|| 729 (25.4%)|| 712 (24.8%)|| 694 (24.2%)|| 2870
|-
| Heat sink, 10<sup>15</sup> [[Calorie|cal]]|| 168 (28.4%)|| 359 (60.7%)|| 63 (10.7%)|| 1 (0.2%)|| 591
|-
|  Ice runoff, km<sup>3</sup>|| 0.57 (81.4%)|| –|| 0.13 (18.6%)|| –|| 0.7
|}

{| Class = "wikitable" style = "text-align: center"
|+
| style="width:25%;"|[[File:Опоры моста в устье Староладожского канала.jpg|center|280px]]
| style="width:25%;"|[[File:Ust Izhora 17.jpg|center|177px]]
| style="width:25%;"|[[File:Peter the Great bridge in context.jpg|center|177px]]
| style="width:25%;"|[[File:Sankt-Petěrburg, řeka Něva.jpg|center|180px]]
|-
|View of the mouth of the [[Ladoga Canal]] and the Neva
|The Neva at the mouth of the [[Izhora]]
|The Neva near the [[Peter the Great Bridge]]
| View from the [[Trinity Bridge (Saint Petersburg)|Trinity Bridge]]
 |}

===Basin, tributaries and distributaries===
The basin area of Neva is 5,000&nbsp;km<sup>2</sup>,<ref>{{cite web|title=Neva, river|url=http://www.encspb.ru/object/2803997867?lc=en|website=Saint Petersburg encyclopaedia|access-date=10 December 2018|archive-date=26 August 2017|archive-url=https://web.archive.org/web/20170826073737/http://www.encspb.ru/object/2803997867?lc=en|url-status=live}}</ref> including the pools of Lake Ladoga and Onega (281,000&nbsp;km<sup>2</sup>). The basin contains 26,300 lakes and has a complex hydrological network of more than 48,300 rivers, however only 26 flow directly into Neva. The main tributaries are [[Mga (river)|Mga]], [[Tosna]], [[Izhora]], [[Slavyanka (river)|Slavyanka]] and Murzinka on the left, and [[Okhta]] and [[Chyornaya Rechka (Saint Petersburg)|Chyornaya Rechka]] on the right side of Neva.<ref name=SPBe/>

The hydrological network had been altered by the development of Saint Petersburg through its entire history. 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. At the end of the 19th century, the delta of Neva consisted of 48 rivers and canals and 101 islands. The most significant distributaries of the delta are listed in the table. Before construction of the [[Obvodny Canal]], the left tributary of that area was the Volkovka; its part at the confluence is now called Monastyrka. The [[Ladoga Canal]] starts at the root of Neva and connects it along the southern coast of Lake Ladoga with the [[Volkhov]].<ref name="Ist-geogr.atlas" />

Some canals of the delta were filled over time, so that only 42 islands remained by 1972, all within the city limits of St. Petersburg. The largest islands are [[Vasilyevsky Island|Vasilyevsky]] at {{convert|1050|ha|acre}}, [[Petrogradsky Island|Petrogradsky]] at {{convert|570|ha|acre}}, [[Krestovsky Island|Krestovsky]] at {{convert|420|ha|acre}}, and [[Dekabristov Island|Dekabristov]] at {{convert|410|ha|acre}}; others include [[Zayachy Island|Zayachy]], Yelagin and [[Kamenny Island]]s.<ref name = "Ist-geogr.atlas"/> At the source of the Neva, near Shlisselburg, there are the two small islands of Orekhovy and Fabrichny. Island Glavryba lies up the river, above the town of [[Otradnoye, Kirovsky District, Leningrad Oblast|Otradnoye]].

{{CSS image crop
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|Description = English map of 1834 depicting the city centre and the names of Neva arms}}

{| Class = "wikitable"
|+ Main waterways of the Neva delta.<ref>{{cite book|title = Leningrad. Historical atlas|location = M.|publisher = Main Office of Geodesy and Cartography under the [[Council of Ministers (Soviet Union)|Council of Ministers of the USSR]]|year = 1981|page = 57|url = https://books.google.com/books?id=sk7LQgAACAAJ}}{{Dead link|date=February 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
! Name
! Region
! Length, km
|-
| Rowspan = "2"|[[Great Neva]]|| from the mouth of the [[Fontanka]] to the [[Blagoveshchensky Bridge]]|| 2.40
|-
| From the Blagoveshchensky Bridge to the [[Palace Bridge]]|| 1.22
|-
| [[Little Neva]]|||| 4.85
|-
| Ekateringofka|||| 3.60
|-
| [[Zhdanovka]]|||| 2.20
|-
| [[Smolenka (river)|Smolenka]]|||| 3.30
|-
| Rowspan = "3"|[[Great Nevka]]|| from the Neva to [[Little Nevka]]|| 3.70
|-
| from Little Nevka to Middle Nevka || 2.05
|-
| From Middle Nevka to [[Neva Bay]]|| 2.15
|-
| [[Middle Nevka]]|||| 2.60
|-
| [[Little Nevka]]|||| 4.90
|-
| [[Karpovka]]|||| 3.00
|-
| Krestovka|||| 0.74
|-
| [[Fontanka]]|||| 6.70
|-
| [[Moyka]]|||| 4.67
|-
| [[Griboyedov Canal]]|||| 5.00
|-
| Pryazhka|||| 1.32
|-
| Kryukov Canal|||| 1.15
|-
| [[Obvodny Canal]]|||| 8.08
|}

=== Flora and fauna ===
There is almost no aquatic vegetation in Neva. The river banks mostly consist of sand, [[podsol]], [[gleysols]], [[peat]], and boggy peat soils.<ref name="Atlas Lo">{{cite book|title = Atlas of Leningrad Oblast|publisher = GUGK at USSR Council|year = 1967|url = https://books.google.com/books?id=_lFwAAAAIAAJ|access-date = 3 December 2021|archive-date = 10 April 2023|archive-url = https://web.archive.org/web/20230410073945/https://books.google.com/books?id=_lFwAAAAIAAJ|url-status = live}}</ref> Several centuries ago, the whole territory of the Neva lowland was covered by [[pine]] and [[Norway spruce|spruce]] [[moss]]y forests. They were gradually reduced by the fires and cutting for technical needs. Extensive damage was caused during [[World War II]]: in Saint Petersburg, the forests were reduced completely, and in the upper reaches down to 40 to 50&nbsp;percent.<ref name=lo>Darinskii, A. V. (1975) [https://books.google.com/books?id=DgYFAAAAMAAJ ''Ленинградская область (Leningrad oblast)''] {{Webarchive|url=https://web.archive.org/web/20230410073958/https://books.google.com/books?id=DgYFAAAAMAAJ |date=10 April 2023 }}. Lenizdat, pp. 48–49</ref> Forest were replanted after the war with spruce, pine, [[Cedrus|cedar]], [[Larix sibirica|Siberian larch]], [[oak]], [[Acer platanoides|Norway maple]], [[elm]], America, [[Fraxinus|ash]], [[apple]] tree, [[mountain ash]] and other species. The shrubs include [[Berberis|barberry]], [[Syringa|lilac]], [[jasmine]], [[hazel]], [[honeysuckle]], [[Crataegus|hawthorn]], [[rose hip]], [[viburnum]], [[juniper]], [[Sambucus|elder]], [[Amelanchier|shadbush]] and many others.<ref>Lihotkin, G. and Milash, N. (1968) [http://www.aroundspb.ru/guide/northeast/bogoslovka/index.php ''Невский лесопарк''] {{Webarchive|url=https://web.archive.org/web/20121125013741/http://www.aroundspb.ru/guide/northeast/bogoslovka/index.php |date=25 November 2012 }}. (Nevsky Forest Park, in Russian). aroundspb.ru.</ref>
[[File:Betula pendula Finland.jpg|thumb|Birch forest]]
Nowadays, the upper regions of the river are dominated by [[birch]] and pine-birch grass-shrub forests and in the middle regions there are swampy pine forests.<ref name="Atlas Lo" />

In St. Petersburg, along the Neva, there are many gardens and parks, including the [[Summer Garden]], [[Field of Mars (Saint Petersburg)|Field of Mars]], Rumyantsev, [[Smolny Convent|Smolny]], [[Alexander Garden (Saint Petersburg)|Alexander Garden]]s, Garden of the [[Alexander Nevsky Lavra]] and many others.<ref name = "Ist-geogr.atlas">''Историко-географический атлас "Ленинград"'' [Historical atlas "Leningrad"]. Moscow: GUGK CM USSR, 1977</ref>

Because of the rapid flow, cold water and lack of quiet pools and aquatic vegetation the diversity of fish species in Neva is small. Permanent residents include such undemanding to environment species as [[perch]], [[ruffe]] and [[Rutilus|roaches]]. Many fish species are transitory, of which commercial value have [[European smelt|smelt]], [[Coregonus albula|vendace]] and partly [[Salmonidae|salmon]].<ref name="Neva">[http://www.nevariver.ru/index.php Все о реке Неве: мосты, притоки, наводнения...] {{Webarchive|url=https://web.archive.org/web/20171227023312/http://www.nevariver.ru/index.php |date=27 December 2017 }} (All of the Neva River: bridges, tributaries, flooding ..., in Russian). nevariver.ru. Accessed 29 November 2022.</ref>

===Floods===
{{main|Floods in Saint Petersburg}}
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 {{convert|160|cm|in}} with respect to a gauge at the [[Saint Petersburg Mining Institute|Mining Institute]]. More than 300 floods occurred after the city was founded in 1703.<ref>{{cite book|url=https://books.google.com/books?id=xMDPksxFhCYC&pg=PA327|page=327|title=Frommer's 500 Places to See Before They Disappear|author=Holly Hughes, Larry West|publisher=Frommer's|year=2008|isbn=978-0-470-18986-3}}</ref><ref>{{cite book|url=http://balticlagoons.net/wp-content/uploads/balloon//2010/04/baloon-NG.pdf|title=The Neva Bay (Russia) – antropogenic lagoon|author=Ryabchuk, D. V.|publisher=All-Russia Research Geological Institute|display-authors=etal|access-date=23 June 2010|archive-date=4 August 2020|archive-url=https://web.archive.org/web/20200804175007/http://balticlagoons.net/wp-content/uploads/balloon//2010/04/baloon-NG.pdf|url-status=live}}</ref><ref>[http://www.edu.joensuu.fi/eno/documents/global4.pdf Water pollution in the hydroelectric power plants area]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Three of them were catastrophic: on 7 November 1824, when water rose to {{convert|421|cm|in}}; on 23 September 1924 when it reached {{convert|369|cm|in}}, and 10 September 1777 when it rose to {{convert|321|cm|in}}.<ref name="Neva" /> However, a much larger flood of {{convert|760|cm|in}} was described in 1691.<ref name=list>[http://www.nevariver.ru/flood_list.php ПОЛНЫЙ ХРОНОЛОГИЧЕСКИЙ СПИСОК НАВОДНЕНИЙ В САНКТ-ПЕТЕРБУРГЕ (ПЕТРОГРАДЕ, ЛЕНИНГРАДЕ)] {{Webarchive|url=https://web.archive.org/web/20120212084816/http://www.nevariver.ru/flood_list.php |date=12 February 2012 }} – a list of floods in St. Petersburg (in Russian). nevariver.ru</ref>

Besides flooding as a result of tidal waves, in 1903, 1921 and 1956 floods were caused by the melting of snow.<ref>{{cite news|author=Morozova, A.|title=Из-за паводка в Петербурге могут разобрать мост|trans-title=A bridge might be removed in St. Petersburg because of the flood|newspaper=[[Komsomolskaya Pravda]]|url=http://spb.kp.ru/online/news/624216/|date=26 February 2010|access-date=23 June 2010|archive-date=31 March 2018|archive-url=https://web.archive.org/web/20180331040736/https://www.spb.kp.ru/online/news/624216/|url-status=live}}</ref>

{|class="wikitable" style="text-align:center"
 |+ Floods in St. Petersburg
 |width="25%"|[[File:7 ноября 1824 года на площади у Большого театра.jpg|center|170px]]
 |width="25%"|[[File:The Flood in St.Petersburg in 1824. 1820-ies.jpg|center|170px]]
 |width="25%"|[[File:Floods in Saint Petersburg 1903 006.jpg|center|210px]]
 |width="25%"|[[File:Floods in Saint Petersburg 1903 005.jpg|center|210px]]
 |-
 |7 November 1824, in front of [[Bolshoi Kamenny Theatre|Bolshoi Theatre]]
 |7 November 1824
 |[[Sadovaya Street]] near the former Nikolsky Market, 15 November 1903
 |Bolshaya Podyacheskaya Street, 25 November 1903
 |-
 |[[File:Floods in Saint Petersburg 1924 001.jpg|center|200px]]
 |[[File:Floods in Saint Petersburg 1924 003.jpg|center|200px]]
 |[[File:Floods in Saint Petersburg 1967 007.jpg|center|200px]]
 |[[File:Floods in Saint Petersburg 1967 008.jpg|center|200px]]
 |-
 |Boat transportation over [[Vasilievsky Island]] during the flood of 23 September 1924
 |Vladimirsky Avenue after the flood of 1924
 |A pier during the flood of 18 October 1967
 |Near the [[Saint Petersburg Mining Institute|Mining Institute]] on 18 October 1967
 |}

===Ecological condition===
The Federal Service for [[Hydrometeorology]] and Environmental Monitoring of Russia classifies the Neva as a "heavily polluted" river. The main pollutants include [[copper]], [[zinc]], [[manganese]], [[nitrite]]s and [[nitrogen]]. The dirtiest tributaries of the Neva are the Mga, Slavyanka, Ohta, and Chernaya.<ref>{{cite web |url= http://www.ghi.aaanet.ru/node/47 |title= КАЧЕСТВО ПОВЕРХНОСТНЫХ ВОД РОССИЙСКОЙ ФЕДЕРАЦИИ |access-date= 2010-06-23 |url-status= dead |archive-url= https://web.archive.org/web/20090419040912/http://www.ghi.aaanet.ru/node/47 |archive-date= 19 April 2009 }} (quality of surface waters of the Russian Federation). Yearbook 2006. Institute of hydrochemistry, Rostov. ghi.aaanet.ru</ref> Hundreds of factories pour wastewater into the Neva within St. Petersburg, and [[petroleum]] is regularly transported along the river. The annual influx of pollutants is 80,000 tonnes,<ref name="Grinpis" /> and the heaviest polluters are Power-and-heating Plant 2 ({{langx|ru|ТЭЦ-2}}), "Plastpolymer" and "[[Obukhov State Plant]]". The biggest polluters in the Leningrad Oblast are the cities of Shlisselburg, Kirovsk and Otradnoye, as well as the Kirov [[thermal power station]]. More than 40 oil spills are registered on the river every year.<ref name="Grinpis 2">{{cite web |url= http://www.greenpeace.org/russia/ru/save-neva/neva |title= Clean Neva |publisher= [[Greenpeace]] |language= ru |url-status= dead |archive-url= https://web.archive.org/web/20100317213427/http://www.greenpeace.org/russia/ru/save-neva/neva |archive-date= 17 March 2010 |access-date= 23 June 2010 }}</ref>

In 2008, the Federal Service of St. Petersburg announced that no beach of the Neva was fit for swimming.<ref name="Grinpis">{{cite web |url= http://www.greenpeace.org/russia/ru/save-neva/project |title= Clean Neva |publisher= [[Greenpeace]] |language= ru |url-status= dead |archive-url= https://web.archive.org/web/20100310173326/http://www.greenpeace.org/russia/ru/save-neva/project |archive-date= 10 March 2010 |access-date= 23 June 2010 }}</ref>

Cleaning of wastewater in Saint Petersburg started in 1979; by 1997, about 74% was purified. This rose to 85% in 2005, to 91.7% by 2008, and Feliks Karamzinov expected it to reach almost 100% by 2011 with the completion of the expansion of the main sewerage plant.<ref name="autogenerated1">{{cite web
 | url = http://eco.rian.ru/shortage/20091020/189781554.html
 | title = В ближайшие два года Петербург будет очищать почти 100% сточных вод
 | trans-title = In the next two years, St. Petersburg will clean almost 100% of wastewater
 | publisher = RIA Novosti
 | date = 20 October 2009
 | quote = К концу года Петербург будет очищать 91,7% сточных вод, а до 2011 года - почти все 100%, сообщил журналистам руководитель ГУП "Водоканал Петербурга" Феликс Кармазинов.
 | access-date = 23 June 2010
 | archive-date = 7 August 2011
 | archive-url = https://web.archive.org/web/20110807134412/http://eco.ria.ru/shortage/20091020/189781554.html
 | url-status = live
 }}</ref>