Нижняя Тунгуска: Описание реки и гидрологические характеристики

The Nizhnyaya Tunguska (, meaning "Lower Tunguska") is a river in Siberia, Russia, that flows through the Irkutsk Oblast and the Krasnoyarsk Krai. The river is a right tributary of the Yenisey joining it at Turukhansk (see Siberian River Routes). The ice free period on the Nizhnyaya Tunguska starts in mid June and ends in the first half of October. The river forms the western limit of the Lena Plateau.

The Nizhnyaya Tunguska is the second largest right tributary of the Yenisey, and joins it near the town of Turukhansk. It is long, and has a drainage basin of According to the character of the stream, constitution of the river's valley and its shores, it can be divided into two parts: the first one starts at the source of the river and continues down to the village Преображенка (Катангский район) (formerly Preobrazhenskoye) and the second section of the river lies downstream of this village in a canyon like relief.

The upper part of Nizhnyaya Tunguska is long and follows a wide valley with flat slopes that was formed by sand and clay deposits. The speed of flow at rafts reaches and drops significantly as the river's channel stretches. This section of river has a meandering channel that closely approaches the Lena, another great Siberian river. The minimum distance between them is as short as in the neighbourhood of Kirensk town. All of the upper course of Nizhnyaya Tunguska is within the Irkutsk Oblast.

The most significant tributaries of Nizhnyaya Tunguska are the rivers entering from the right: Yeyka, Kochechum, Yambukan, Vivi, Tutonchana, Erachimo, and Severnaya. Entering from the left are the Nepa, Большая Ерёма, Teteya, Ilimpeya, Nidym, Taymura, and Uchami. The most prominent tributary is Kochechum, which joins the main stem from the north near Tura. The average annual discharge of the Kochechum is , and its basin covers nearly
On the whole, the right tributaries of Nizhnyaya Tunguska dominate over the left and add more water. The river has no big lakes in its basin; the biggest is Vivi with a surface area of Inflows to the Nizhnyaya Tunguska are strongly seasonal.

The value of average water discharge of Nizhnyaya Tunguska gives it eleventh place amongst largest rivers of Russia. The annual water discharge at the river's mouth is equal to The minimum value observed in 1967 was ; the maximum was in 1974 or, respectively, for the estuary of the river it was about and about The water supply of the river is from melting snow and summer rains. During winter season Nizhnyaya Tunguska contains little water as its basin lies in the region of permafrost and it has no subterranean water sources. According hydrological observations during 52 years, the minimum average monthly discharge was in March 1969—it was exceptionally dry winter—and the maximum value corresponds to June 1959 and was The diagram below contains mean values of monthly average discharges calculated on the base of a 52 year long period of observations at hydrological station "Bolshoy Porog" (фактория Большой Порог, Bolshoy Porog factory). Seventy three per cent of the entire annual water yield occurs during the spring–summer season.

The channel of Nizhnyaya Tunguska with its tributaries constitutes dense network of rivers and creeks which creates convenient summer pathways through the wide rifted valley of Eastern Siberia. Historically, the river was used as a route for the fur trade, fishery, for transportation of goods and mineral resources. Hunting and fur trade is still a significant part of the local economy.

Navigation on the river is difficult because of a number of rifts, rapids and whirlpools. The passage of large ships and barges is possible during the spring inundation, and rainy weather during particular years allows short periods of navigation at the end of summer or the start of autumn. The most problematic for the safe navigation of ships are the rapids "Bolshoy", which are from the river's mouth. In 1927 the first steamship passed this rapids and it is considered to be the start of modern navigation on the river from Turukhansk to Tura. As of 2010 the shipping routes of Yenisey River Steamship Lines ([[:ru:Енисейское речное пароходство) includes the village Kislokan, from the estuary. In the beginning of 20th century the canal project was considered inexpedient due to its complexity and high cost.

Plans to dam the river existed since the early Soviet period. These plans were the subject of criticism by various ecologists. Construction of the dams also became impossible after disintegration of Soviet Union due to economic reasons. In 2005–10 the interest to this project and the discussion of it revived to some extent. According news media the construction of the Turukhanskaya hydroelectric powerplant would begin as soon as in 2010. Since the precise date is unknown, a more likely start up is between 2010 and 2020. After completion of this project Nizhnyaya Tunguska will be dammed, flooding about of forest and tundra (roughly the size of Lebanon or the islands of Hawaii), some of which contains buried nuclear waste, and displacing the indigenous Evenk population. The cost of the plant is estimated at $13 billion dollars, which includes costs of electric power lines. The plant will be built and operated by RusHydro in the Krasnoyarsk region, and the electricity will be channeled to European Russia via a system of power lines. At some periods it was called Troitskaya Tunguska (Троицкая Тунгуска), Monastyrskaya Tunguska (Монастырская Тунгуске) and Mangaseyan Tunguska (Мангазейская Тунгуска, see Mangaseya). In literature, the river Nizhnyaya Tunguska is described in the novel Gloomy River by Vyacheslav Shishkov. This writer of the first half of the 20th century visited the river during an expedition in 1911; the name "Gloomy River" was taken from a Siberian song. Existing sources indicate that the annual average discharge of water at mouth of its tributary Severnaya is equal to As this river joins Nizhnyaya Tunguska downstream of hydrological station "Bolshoy Porog" it means that the known average discharge at mouth of Nizhnyaya Tunguska is significantly underestimated. It must be in the range of .