The mouth of the Lena River and the source

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:47

The mouth of the Lena River begins 150 km from the coast of the Laptev Sea, after it, bypassing the island of Stolb, is divided into many channels (there are more than 150 of them). They fan out over a huge area of 45,500 km2, forming a classic river delta.

Let's start the description of the river from the very beginning - from its source. At the same time, we will take the characteristics of the parameters from the officially documented information of the Water Register of the Russian Federation.

Source of the river

The small lake Negedeen, according to the State Water Register, is the source of the Lena River. It is located 7 km from Lake Baikal, on the western side of the foot of the nameless mountain of the Baikal Range with a mark of 2023 m. The coordinates of the source are determined by the values: northern latitude 53 degrees 56 minutes, eastern longitude 108 degrees 5 minutes. Administratively, this is the territory of the Kachugsky district of the Irkutsk region. The great Siberian river begins with a smalla stream that a five-year-old can cross. Here the channel of the Lena is subject to freezing and drying up. But after the first tributaries flow into it, it acquires a constant flow.

Source and mouth of the river

Lena is located in Eastern Siberia. The river flows through the Irkutsk Region and Yakutia, receiving tributaries from Transbaikalia, Buryatia, Krasnoyarsk and Khabarovsk Territories.

The zero value marks the height of the river mouth. Lena has a length of 4294 km - this distance is registered in the state register of surface water bodies of Russia. The full fall is 1650 m - the difference in water levels between the source (1650 m) and the mouth (0 m). The average slope is 0.38 m/km. Theoretically, this means that with each kilometer in the direction of the river flow, the earth's surface decreases by an average of 38 cm. In fact, the slope of the channel and the speed of the flow in the upper reaches of the river are many times greater than the values of these hydrological characteristics at the mouth of the Lena River. These characteristics depend on the terrain.

Upstream

The source and mouth of the river are located in different geographical conditions. Lena begins in the mountain system of Cis-Baikal, then crosses the Patom Highlands, enters the Prilenskoye Plateau and descends into the Central Yakut Lowland. Therefore, the watercourse is conditionally divided into 3 approximately equal parts. The first of them is the upper reaches of the Lena, from the beginning to the confluence of the Vitim River. The length is 1580 km. The elevation of the mouth of the Vitim is 176 m, therefore, the average slope of the upper part of the Lena is 0.93 m/km. The river bed in the upper reaches is winding and rapids, flows in a valley constrained by mountains. When approaching Vitim, it becomes wide (up to 2 km) and deep (up to 12 m), sometimes divided into branches by islands. The asymmetric river valley with a pronounced floodplain and terraces extends in breadth in places up to 30 km. The left bank is gently sloping - this is the Central Siberian Plateau. The right bank is steep and high - the outskirts of the Patom Highlands. The slopes on both sides are covered with taiga, sometimes replaced by meadows.

Middle Current

This part of the Lena, 1415 km long, is bounded by the mouths of the largest tributaries, starting from the confluence of the Vitim (mark 176 m) and ending with the Aldan (mark 72 m). The average slope is 0.074 m/km. Lena after Vitim becomes a full-flowing river. After confluence at 2089 km from the mouth of the Olekma River, the Lena valley narrows. The shores are rocky, they are composed of limestone. These are the Lena Pillars - they are sheer, have bizarre outlines. Near the city of Pokrovsk, the Lena breaks out onto the plain, the valley widens to 20 km or more, and the floodplain covers a strip up to 15 km wide. The flow speed is slowing down - from 1.5 m/s to 0.5 m/s.

Downstream

From the mouth of the Aldan to the Laptev Sea, the lower Lena stretches. The length of this part of the river is 1300 km. With the confluence of powerful tributaries (Aldan and Vilyui), Lena becomes a giant river. The width of its single-branch channel with a depth of up to 20 m reaches 10 km, and where island formations are located, it reaches 25 km. Flowthe river is majestic - it slows down due to a slight slope, which is 0.05 m / km or less in the lower part of the river.

The mouth of the Lena River

Photo from space shows the beauty and scope of the northern hemisphere's largest river delta. With its area, it exceeds the famous mouth of the Nile by 20 thousand km2. The top of the delta is Stolb Island, 150 km from the sea coast. The channel of the Lena is divided into one and a half hundred channels. The largest of them are three: Olenekskaya (limits the delta from the west), Bykovskaya (eastern) and Trofimovskaya (middle), through which 70% of the annual runoff is discharged into the sea. Navigation is carried out along the Bykovskaya channel, on which the seaport of Tiksi stands.

Since 1986, the mouth of the Lena has acquired the status of a biosphere reserve in Russia - Ust-Lensky. This is a unique habitat of tundra communities, represented by dozens of species of Red Book plants, 32 species of mammals. There are massive nesting sites of waterfowl, returning here every year to procreate and molt. The ichthyofauna is diverse and rich.

Hydrology

The catchment area of the Lena is 2.49 million km². The annual runoff in different years ranges from 490 to 540 km³. The average annual discharge at gauging stations at the mouth of the Lena River ranges from 15.5 to 17.8 thousand m^3/s.

The river is fed by atmospheric precipitation, distributed in volumes approximately equally between snow melt and rain. On thegroundwater recharge is less than 2% due to permafrost conditions.

The river is characterized by high spring floods, the passage of several large floods in summer and autumn-winter low water with a decrease in water flow in the lower reaches to 370 m3/s.

The ice regime of the Lena is different from other rivers with a thick layer of hard ice, which forms in the conditions of a long cold winter with little snow. In the upper reaches, the period without ice cover of the river lasts up to six months, in the lower reaches - a month or two less. Freezing occurs in the upper reaches at the end of October, and in the lower reaches at the end of September. Ice begins to break up from the upper reaches by mid-May, and in June - at the mouth of the Lena River. In meters, the excess of the flood level over the low water reaches values from 8 to 18, which causes flooding of low areas and emergency situations in settlements along the banks of the river.

Unique landscapes

The pristine beauty and richness of nature, both at the source and at the mouth of the Lena River, are impressive. But the shores in the Lena Pillars National Natural Park, which is a UNESCO World Heritage Site, look especially fabulous. The Lena Pillars begin 180 km upstream from Yakutsk and extend for many kilometers along the right bank and in some places along the left bank.

Sheer limestone cliffs up to 200 m high represent a geological and landscape phenomenon. Another miracle is the mountains of the purest and lightest waving sands -tukulans. At the mouth of the Deering-Yuryakh tributary, sites of primitive man were found. Fossils of ancient fauna were found in the park: the remains of a mammoth, bison and rhinos.

Interesting legends can be heard from local residents about the mouth of the Lena River. The underground city with streets and eternal lamps, according to local residents, is located near the sea coast. You just need to find a secret entrance to it. They also say that a German submarine moored to Stolb Island at the top of the delta during the Great Patriotic War.