Lake Sapsho

Lake Sapsho
Location	Smolensk Oblast, Russia
Coordinates	55°29′44″N 31°50′43″E / 55.49556°N 31.84528°ECoordinates: 55°29′44″N 31°50′43″E / 55.49556°N 31.84528°E
Lake type	Glacial lake
Primary inflows	Sapsha, Sapshanka
Primary outflows	Sapsha
Basin countries	Russia
Surface area	3.04 km^2 (1.17 sq mi)
Average depth	6.9 m (23 ft)
Max. depth	18.6 m (61 ft)
Water volume	0.021 km^3 (0.005 cu mi)
Shore length^1	7.8 km (4.85 mi)
Surface elevation	172.7 m (567 ft)
Frozen	November–April
Islands	6
Settlements	Przhevalskoye
^1 Shore length is not a well-defined measure.

Lake Sapsho (Russian: Сапшо́) is a glacial lake. It is the largest lake^[1][2] (3,04 km²) of the national park Smolenskoye Poozyorye (Russian: Смоле́нское Поозё́рье) in Demidovsky District of Smolensk Oblast, Russia. It is situated northeast of Demidov in the northwestern part of the oblast, near the settlement of Przhevalskoye. A famous Russian traveller of the 19th century Nikolai Przhevalsky compared the lake with Lake Baikal in miniature.^[3][4] The lake is a natural monument.^[5][6] It is connected with the Baltic Sea by rivers Sapsha, Vasilyevka, Yelsha, and Daugava. There are 4 big and 2 small islands on the lake. There are a lot of tumuli of the Tushumlin culture by Lake Sapsho.^[7][8] The flora and fauna of the lake are very diverse. Yet in the beginning of the 20th century there was the industrial fishery.^[9] Though now any industry is prohibited here. A lot of species of the flora and fauna of the lake are in the Red Book.^[10]

Geography and hydrography

The Lake

The bottom of Lake Sapsho

Lake Sapsho is situted at the north-west of Smolensk Oblast, 120 km (75 mi) to the north of Smolensk. It is on Sloboda Upland (Russian: Слободская возвышенность) that is a part of Smolensk–Moscow Upland (Russian: Смоленско-Московская возвышенность). It is the largest lake in the National Park Smolenskoye Poozyorye^[11] (Russian: Смоленское Поозёрье). There are two eskers. One of them is partly destroyed by glacial flows. It caused the arising of five of six islands. The Sapsho is divided into deep northern and shallow southern parts. The other esker forms the western border of the lake. The northern side is also abrupt. On the contrary, the eastern and southern sides are gentle. The bottom of the lake here is also not steep. The northern basin is divided into western and eastern parts by a long underwater spit. The depth here is less than 5 m (16 ft). It ends with a long shoal with depth less than 1 m (3 ft 3 in), a so-called "underwater island" or "sitnik".

The Sapsho drains into the rivers of the Western Dvina (Russian: Западная Двина) basin. In spring, usually by the middle or end of April, water volume increases because of melting snow. The melting of ice on the lake usually takes from 10 to 15 days more, and ends in the late April or early May. The swimming season opens in late June or early July, and finishes in late July or early August. The lake usually covers with ice in the 2nd or 3rd decade of November. Sometimes, it happens in the middle of December. The thickness of ice is from 50 cm (20 in) to 70 cm (28 in). In most severe winters it may become up to 90 cm (35 in). The period of freeze-up is from 150 to 170 days.^[12]

Surface elevation of Lake Petrakovskoye and Lake Sapsho

The Rivers

Inflow rivers are Sapshanka (Russian: Сапшанка) on the South and Sapsha (Russian: Сапша) on the West. The outflow river is Sapsha on the East. Sapsha flows through a valley. It connects Lake Sapsho (Russian: Сапшо́) and Lake Petrakovskoye (Russian: Петраковское). Both lakes have similar surface elevation. The area of Lake Petrakovskoye is 0.17 km² (0.066 sq mi). During the period of melting snow in spring and heavy showers in summer the Petrakovskoye fills with water faster than the Sapsho. Therefore, River Sapsha changes its flow. Usually changing of flow of the Sapsha happens several times a year.

Lake Sapsho and Lake Petrakovskoye on the map of Przhevalskoye

The Islands

There 6 islands on the lake. Four of them are large: Chernetsky / Monk Island (Russian: Чернецкий), Raspashnoy / Border Island (Russian: Распашной), Bagryany / Crimson Island (Russian: Багряный), Dlinny / Long Island (Russian: Длинный). Two of them are small: Dubovy / Oak Island (Russian: Дубовый) and Lyubvi / Island of Love (Russian: Любви). Five of them are located in line along one of two eskers.

At Lake Sapsho in winter

See also

• Przhevalskoye
• National Park Smolenskoye Poozyorye

References

1. Национальный парк «Смоленское Поозерье»: Справочно-информационное издание / Под ред. А. С. Кочергина. — 2-е изд., перераб. и доп. — Смоленск: Маджента, 2006. — С. 72
2. Lake Schuchye also may be considered to be the largest (11,85 km²), but only its small western part is included into the territorium of the national park
3. Письмо от 9 июня 1881 года
4. Мусиенко Н. Сапшо — словно Байкал в миниатюре // Правда, № 37, 24 мая 2009.
5. СМОЛЕНСКОЕ ПООЗЕРЬЕ - национальный парк
6. Экологическая тропа "Сапшо" [MS/1372]
7. Шмидт Е. А. Древнерусские археологические памятники Смоленской области. — Ч. I. — М., 1982. — С. 53
8. О тушемлинской культуре IV—VII веков в Верхнем Поднепровье и Подвинье
9. Гавриленков В.М., Гавриленкова Е.П. На берегах «Смоленского Байкала» (очерки истории Слободского края). — Смоленское издательство «Смядынь», 2000. — С. 43.
10. Национальный парк «Смоленское Поозерье»: Справочно-информационное издание / Под ред. А. С. Кочергина. — 2-е изд., перераб. и доп. — Смоленск: Маджента, 2006. — С. 77-78
11. Национальный парк «Смоленское Поозерье»: Справочно-информационное издание / Под ред. А. С. Кочергина. — 2-е изд., перераб. и доп. — Смоленск: Маджента, 2006. — С. 16-17
12. Национальный парк «Смоленское Поозерье»: Справочно-информационное издание / Под ред. А. С. Кочергина. — 2-е изд., перераб. и доп. — Смоленск: Маджента, 2006. — С. 28