Olyokma River

Oljokma with catchment area (yellow)

Catchment area of ​​the Oljokma with inflows

The 1436 km long Oljokma (Russian Олёкма, also Olekma; Yakut Өлүөхүмэ ( Öluöchume ) ) is a right tributary of the Lena, in Siberia (Russia, Asia).

Course

The Oljokma rises in the mountain range Oljokminski Stanowik (Russian Олёкминский Становик ) in the northeastern part of the Jablonowygebirges in the region of Transbaikalia. From there it flows in a northerly initially, later increased northeast through the sparsely populated high mountain between the western and the eastern Stanowoihochland Stanowoigebirge.

After the confluence of the Tungir she turns again to the north and crossed the border to Amur Oblast, the northwestern corner you traversed in a widening valley. In Ust- Njukscha opens the Njukscha, their greatest right tributary, a. From here on the Baikal - Amur Mainline runs to the confluence of Chani in the valley of the river.

Shortly before the opening of the Chani the Oljokma reached the Sakha Republic. Here the valley narrows again, while the Oljokma between the Stanowoigebirge to the east and the west Udokanplateau flows remains concentrated in the north. About 30 km before its mouth it unites near Ust- Tschara with its largest tributary, the Chara. She leaves the mountains and now flows in the broad valley of the Lena, in which it flows near Oljokminsk.

Hydrology and use

The Oljokma is mainly fed by rain and snow melt water. Your lowest water levels it has in late winter from February to early April, when it is frozen to the depth. The approximately a week-long break the ice begins in May and is followed by spring floods, which reached its peak in June and provide 37 % of the annual runoff. In October, she then freezes again.

The Oljokma flows almost throughout its run in a narrow mountain valley. The narrowness of the valley and the high outflow provide a high flow of 5-5.5 m / s Only in the last kilometers, according to the confluence of Chara and the occurrence in the wide valley of the Lena drops them on 0.5-1.2 m / s. In the ice-free period and after the floods the Oljokma is navigable, despite their high flow rate and numerous rapids. It is used for water supply and tourism.