Lake Ladoga(redirected from Laatokka)
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Ladoga, Lake(lä`dōgə, Rus. lä`dəgə), Finnish Laatokka, Rus. Ladozhskoye Ozero, c.7,000 sq mi (18,100 sq km), NW European Russia, in Karelia, NE of St. Petersburg. The largest lake in Europe, it is c.130 mi (210 km) long and c.80 mi (130 km) wide and has a maximum depth of 738 ft (225 m). Located on the heavily glaciated Baltic Shield, the lake has shores that are low and marshy in the south, rocky and indented in the north. It is subject to autumn storms and freezes every year for two months in the north and four months in the south. Chief among the many rivers that feed the lake are the Svir, descending from Lake Onega; the Vuoska, which forms the outlet of the Saimaa lake system of Finland; and the Volkhov, coming from Lake Ilmen. The main outlet is the Neva, which flows W into the Gulf of Finland at St. Petersburg. The fortress at Petrokrepost commands the Neva's exit from the lake. Among the many islands in the northern part of the lake is Valaam (Finnish Valama or Valamo), with a famous Russian monastery dating from the 12th cent. or earlier. Until the Finnish-Russian WarFinnish-Russian War,
1939–40, war between Finland and the Soviet Union. After World War II broke out in Sept., 1939, the USSR, never on cordial terms with Finland, took advantage of its nonaggression pact (Aug.
..... Click the link for more information. of 1939–40, the northern part of the lake belonged to Finland; cession of the Finnish shore to the USSR was confirmed by the peace treaty of 1947. During the defense of St. Petersburg (then Leningrad) against the Germans in World War II, the frozen Lake Ladoga was the lifeline by which Leningrad was supplied in the winters from 1941 to 1943. Because of the difficulties of navigation, the southern shore of Lake Ladoga is paralleled by the Ladoga Canals, c.100 mi (160 km) long, connecting the Svir and Neva rivers and forming part of the Mariinsk System (see Volga-Baltic WaterwayVolga-Baltic Waterway,
canal and river system, c.685 mi (1,100 km) long, N European Russia. It links the Volga River and the St. Petersburg industrial area. It consists of the Moscow-Volga Canal, the Volga River, the Rybinsk Reservoir, the Mariinsk system (composed of the
..... Click the link for more information. ) and the Baltic–White Sea Canal System.
a lake in the northwestern European USSR. Located in the Karelian ASSR and in Leningrad Oblast of the RSFSR, it is the largest lake in Europe (area, 17,700 sq km; 18,135 sq km, including islands). The lake is 219 km long, and its average width is 83 km. Its average depth is 51 m. (The maximum depth is 230 m in the northern part to the west of Valaam Island.) The area of its basin is 276,000 sq km. The Lake Ladoga depression is of tectonic origin and was transformed by the action of Quaternary glaciers. The total volume of water in the depression is 908 cu km.
The northern banks of Lake Ladoga are, for the most part, high, precipitous, deeply cut by fjordlike inlets, and covered with forests. The numerous islands, most of which are wooded, form skerries in this region. The southern shores are primarily low, weakly dissected, and overgrown with willow and alder. There are many boulder and sand beaches, and in places ancient beach barriers are overgrown with pines. The floor of the northern part of the lake has a complex relief characterized by the alternation of deep trenches and shallower parts. Depths of more than 100 m prevail. In the southern part of the lake the floor is more even. Toward the south the depths decrease from 100 m to 10 m or less. There are many sand and rock bars and shoals. In the northern and central deep-water regions the floor is made up of silt, whereas in the southern region it consists of boulders and sand. Along the shores there are accumulations of boulders in many areas. Lake Ladoga has about 660 islands, with a combined area of 435 sq km. About 500 of the islands are located along the northwestern coast, and about 65 are in the central part of the lake (the Valaam Islands and the Western Archipelago). The largest islands are Riskalansari, Mantsinsari, Kil’pola, Tulolansari, and Valaam.
The climate is moderately cold. The average February temperature ranges from − 8° to − 10°C, and the average July temperature is 16°-17°C. The average annual precipitation is about 550 mm. There are about 50,000 lakes in the Lake Ladoga basin, as well as 3,500 rivers more than 10 km long. The largest tributaries are the Volkhov (from the south), the Svir’ (from the southeast), and the Vuoksa (from the west). River waters (primarily from the Svir’, Vuoksa, and Volkhov) provide 85 percent of the lake’s incoming water (an average of 67.8 cu km of water a year), precipitation accounts for 13 percent, and groundwater for 2 percent. Of the outflow, 92 percent goes into the Neva River (an average of 78.1 cu km a year), and 8 percent evaporates from the surface.
Variations in water level are gradual. The average level is 4 m. The highest water levels occur in June and July, and the lowest in December and January. The average annual range of variations in water level is about 0.8 m (the abscissa is about 3 m). Surge variations in water level are 5–10 cm in the northern part and up to 20–40 cm (more rarely up to 90 cm) in the southern part. Seiches have been observed. The maximum height of waves in the northern and central parts of the lake is 3–3.5 m, and more rarely 5–6 m. In the southern part the waves may be up to 2.5 m high. Storms occur frequently in the autumn.
Thermal conditions differ in the deep-water central part and in the shallow coastal areas of the lake. In August the average temperature of the surface is about 16°C, and the maximum temperature is 25°C. The temperature of water layers near the bottom varies from 2°-2.5°C in the winter and up to 4°-5°C in the summer. The coastal regions and inlets of Lake Ladoga generally freeze over in early December, and the open central part, in January and February. The average thickness of the ice is 50–60 cm (maximum thickness, 90–100 cm). In the central part of the lake the ice breaks up in March and early April, and in the northern part, in early May.
The water is yellow-brown. The average transparency in the central part of the lake is 4.5 m; along the western shore, 2–2.5m; along the eastern shore, 1–2 m; and where the rivers flow into the lake, 0.3–0.9 m. The greatest transparency is 8–10 m (west of Valaam Island). The lake has fresh hydrocarbonate-calcium water. The average mineralization is 56 mg per l (liter). In the winter the water contains 14–15 mg of dissolved oxygen per l, and in the summer, 10–11 mg per l in the surface layers and 12–13 mg per l in deep-lying strata. The lake is rich in fish. Among the commercially important are Atlantic salmon, trout, whitefish, vendace, pike perch, bream, perch, roach, pike, and smelt. Russian sturgeon, eel, and other fishes are also found in the lake, as are seals. Lake Ladoga is navigable and is part of the Volga-Baltic Waterway. The Novaia Ladoga Bypass Canal runs along the south shore from the Svir’ River to the Neva.
In ancient times the lake was called the Nevo, but from the 13th century it was called Ladoga after the ancient Russian city of Ladoga (ninth century). In the eighth and ninth centuries the Slovene tribe lived on the south shore of Lake Ladoga. The route “from the Varangians to the Greeks” passed along the lake. The cities of Korela (tenth century) and Oreshek (1323) were founded on its shore, and the Konevits and Valaam monasteries were built on the islands of Konevits and Valaam. During the Livonian Wars of 1558–83 military operations took place near Lake Ladoga. In the early 17th century the Swedes occupied the western, southern, and northern shores of the lake. According to the Stolbovo Peace Treaty of 1617 the northern and western shores passed from Russia to Sweden. During the Northern War of 1700–21 military operations between the Russians and Swedes took place on Lake Ladoga. According to the Treaty of Nystadt (1721), the shore of the lake was returned to Russia. The Ladoga Naval Flotilla operated on the lake during the Soviet-Finnish War of 1939–40 and the Great Patriotic War of 1941–45, playing an important part in the successful outcome of combat operations of the Leningrad Front and the Baltic Fleet.
Between September 1941 and March 1943 the Road of Life (Doroga zhizni), which connected the country with the blockaded city of Leningrad, went across the southwestern part of Lake Ladoga. Cities on the shore of the lake are Priozersk, Petrokrepost’, Novaia Ladoga, and Sortavala.
REFERENCESGidrologicheskii rezhim i vodnyi balans Ladozhskogo ozera. Leningrad, 1966. (Trudy Laboratorii ozerovedeniia LGU, vol. 20.)
Semenovich, N. I. Donnye otlozhenito Ladozhskogo ozera. Moscow-Leningrad, 1966.
Biologicheskie resursy Ladozhskogo ozera. Leningrad, 1968.
Kalesnik, S. V. Ladoshskoe ozero. Leningrad, 1968.
Domanitskii, A. P., R. G. Dubrovina, and A. I. Isaeva. Reki i ozera Sovetskogo Soiuza. Leningrad, 1971.
B. B. BOGOSLOVSKII