The Lena River is the largest river in North-Eastern Siberia, flows into the Laptev sea. The tenth in the world in terms of the length of the river and the eighth in the world in terms of high water content, flows through the territory of the Irkutsk region and Yakutia, some of its tributaries belong to Transbaikal, Krasnoyarsk, Khabarovsk, and the Republic of Buryatia. Lena - the largest of the Russian rivers, whose basin lies entirely within the country. Freezes in the reverse autopsy order - from the lower reaches to the upper reaches.Geographical position
According to the nature of the current of the river, three parts are distinguished: from the source to the mouth of Vitim; From the mouth of Vitim to the point of confluence Aldan And the third lower section - from the confluence of the Aldan to the mouth.
The source of Lena is a small lake in 12 kilometers from Lake Baikal, located at an altitude of 1470 meters. At the beginning of 19 August 1997, a chapel with a commemorative plaque was erected. The entire upper course of the Lena before the confluence of Vitim, that is, almost a third of its length, falls on the mountainous Baikal region. Water flow in the area of Kirensk - 1100 m3/ Sec. To the middle current is its segment between the mouths of the Vitim and Aldan rivers, length 1415 km. Near the confluence of Vitim Lena enters the boundaries of Yakutia and flows along it to the mouth. Having adopted Vitim, Lena turns into a very large river. Depths increase to 10-12 m, the channel expands, and in it there are numerous islands, the valley extends to 20-30 km. The valley is asymmetric: the left slope is colder; Right, represented by the northern edge of the Patom Highlands, steeper and higher. On both slopes grow dense coniferous forests, only occasionally replaced by meadows. From Olekma to Aldan, Lena does not have a single significant inflow. More than 500 km Lena flows in a deep and narrow valley, embedded in limestone. Below the city of Pokrovsk there is a sharp expansion of the Lena valley. The current velocity is greatly slowed down, it never exceeds 1,3 m / s, and mostly falls to 0,5-0,7 m / s. Only the floodplain has a width of five to seven, and in some places 15 km, and the entire valley has a width of 20 and more kilometers. Below Yakutsk, Lena accepts two of its main tributaries, Aldan and Viluy. Now this is a giant water stream; Even where it goes by one channel, its width reaches 10 km, and the depth exceeds 16-20 m. There, too, where there are a lot of islands, Lena spills on 20-30 km. The banks of the river are harsh and deserted. Settlements are very rare. In the lower reaches of the Lena, its basin is very narrow: spurs come from the east Verkhoyansk Ridge - watershed of the Lena and Yana rivers, from the west insignificant elevations of the Central Siberian plateau are shared by the basins of the Lena and the Olenyok River. Below the village of Bulun River, the Charaulakh ranges from the east and Chekanovskiy from the west are close to it. Approximately 150 km from the sea begins the extensive Lena delta.
Hydrology of the river
The length of the river is 4400 km, the basin area is 2490 thousand km2. The main food, as well as almost all the tributaries, is thawed snow and rain water. The widespread distribution of permafrost interferes with the feeding of rivers by groundwater, except for geothermal sources. In connection with the general regime of precipitation for Lena characterized by spring floods, several fairly high floods in the summer and low autumn-winter lowlands to 366 m3/ S at the mouth. Spring ice drift is very powerful and often accompanied by ice jams. The highest average monthly water discharge in the estuary was observed in June of 1989 and was 104 000 m3/ S, the maximum discharge of water at the mouth during the flood may exceed 250 000 m3/from. Hydrological data on the flow of water at the mouth of the Lena in different sources contradict each other and often contain errors. The river is characterized by periodic significant increases in annual runoff, which do not occur due to the large amount of precipitation in the basin, but primarily because of the intensive thawing of ice and permafrost in the lower part of the basin. Such phenomena occur during the warm years in the north of Yakutia and lead to a significant increase in runoff. For example, in 1989, the average annual water discharge was 23 624 m3/ S, which corresponds to 744 km3 in year. For 67 years of observations at the station "Kyusyur" near the mouth of the average annual water discharge is 17 175 m3/ S or 541 km3 Per year, had a minimum value in 1986 year - 13 044 m3/from.
First of all, at the end of April, the spring flood begins in the area of Kirensk - on the upper Lena - and, gradually shifting to the north, stepping on the still ice-bound river, reaches the lower reaches in the middle of June. Water rises during the spill on 6-8 m above the low-water level. In the lower reaches, the rise of water reaches 10 m. On the broad expanses of the Lena and in the places of its narrowing, the ice drift is formidable and beautiful. Large tributaries of the Lena significantly increase its water content, but, in general, the increase in expenditure occurs from the top downward fairly evenly.Economic use
Lena until today remains the main transport artery of Yakutia, connecting its regions with the federal transport infrastructure. Lena produces the bulk of the "northern deliveries". The beginning of navigation is the quay of Kachug, however, only small vessels pass through it from the port of Osetrova upstream. Below the city of Ust-Kut, right up to the confluence of the Vitim tributary on the Lena, there are still many difficult sections for navigation and relatively small places that compel each year to work on deepening the bottom. The navigation period lasts from 125 to 170 days.