Lake Baikal

Topic: World Physical Features and Natural Regions · NCERT: Beyond NCERT

Meaning

Lake Baikal is a rift lake in south-eastern Siberia, Russia, just north of Mongolia. It is the oldest lake in the world (about 25 million years) and the deepest (about 1,700 m according to UNESCO; NCERT gives about 1,642 m). It holds about 20% of the world's unfrozen fresh water [1].

It matters because it holds three world records at once: oldest, deepest and one of the biggest stores of fresh water. It is also a UNESCO World Heritage Site with a large number of plants and animals found nowhere else, so it is often asked about in the exam.

Explanation

How a rift lake forms

• Cause: the crust is pulled apart.
• Forces inside the Earth stretch the crust (the Earth's outer rocky layer).

• Two long, parallel faults form. A fault is a crack in the crust along which rocks move.

• Process: a rift valley forms.

• The strip of land between the two faults sinks down.

• This sunken strip is called a rift valley.

• Result: a long, deep lake.

• Water fills the rift valley.
• Because the land sank a long way, the lake is long, narrow and very deep. Baikal is the best example.

Why Baikal is so old and so deep

• Old: the rift that holds Baikal formed about 25 million years ago [1]. Most lakes are much younger. Many filled hollows left by Ice Age glaciers, and those hollows slowly fill up with mud and disappear.
• Deep: the floor of the rift kept sinking over millions of years. That is why the lake reaches about 1,700 m (UNESCO) [1]. NCERT gives about 1,642 m.
• Huge store of water: the lake is very deep, so it holds a very large amount of water even though other lakes cover more area. It has about 20% of the world's unfrozen fresh water [1].

Biodiversity: the "Galapagos of Russia"

• Why so many unique species: the lake is very old and cut off from other water bodies. Over a long time, its plants and animals changed in their own way. This gave rise to unusual wildlife [1].
• Numbers [1]:
• About 1,340 animal species, of which 745 are endemic. Endemic means found nowhere else in the world.

• About 570 plant species, of which 150 are endemic.

• Nerpa (Baikal seal): one of the few seals that live only in fresh water.

World Heritage status

• Listed in 1996 by UNESCO as the most outstanding example of a freshwater ecosystem (a community of living things together with their water surroundings) [1].
• Listed under natural criteria (vii), (viii), (ix) and (x). These cover natural beauty, Earth's history, ecological processes and biodiversity [1].
• The protected property covers 3.15 million hectares [1].

Where it occurs

• Lake Baikal: south-eastern Siberia, Russia, just north of Mongolia.
• Other rift lakes, for comparison (Africa):
• Tanganyika: Tanzania, DR Congo, Burundi, Zambia. It lies in the Western Rift of the East African Rift. It is the second deepest lake (about 1,470 m) after Baikal.

• Malawi (Nyasa): Malawi, Mozambique, Tanzania. It lies south of Tanganyika, at the southern end of the Western Rift.

• Other Asian lakes in the same notes: the Caspian Sea (largest inland water body), the Aral Sea (Kazakhstan–Uzbekistan) and Balkhash (Kazakhstan). None of these is a rift lake.

Don't confuse with

• Caspian Sea: the largest inland water body by area (about 371,000 sq km). But it is saltwater and sits in a closed basin. Baikal is the deepest and oldest, and its water is fresh.
• Lake Superior: the largest freshwater lake by area (about 82,100 sq km) [3]. Baikal is the deepest lake, not the largest by area.
• Lake Tanganyika: the longest freshwater lake (about 670 km) and the second deepest (about 1,470 m). Baikal is first in depth.
• Lake Victoria: Africa's largest lake. It sits on a plateau between the two arms of the East African Rift, so it is not a rift lake. Baikal, Tanganyika and Malawi are rift lakes.

Prelims Hooks

• Deepest and oldest lake in the world: Baikal (about 1,700 m per UNESCO; about 1,642 m per NCERT; about 25 million years old) [1].
• Depth order, deepest first: Baikal > Tanganyika > Malawi.
• Type: Baikal is a rift lake, like Tanganyika and Malawi. Trap: Lake Victoria is not a rift lake.
• Lake Baikal became a UNESCO World Heritage Site in 1996 and holds about 20% of the world's unfrozen fresh water [1].
• Nerpa (Baikal seal): one of the few seals that live only in fresh water. Baikal is called the "Galapagos of Russia" [1].
• Endemic count: about 745 of 1,340 animal species and 150 of 570 plant species are endemic [1].

Mains Points

• Threats to lake biodiversity (GS-III): Baikal's endemic species took millions of years to evolve, so pollution can wipe them out for good.
• Compare with Lake Victoria, where the invasive Nile perch ate many native cichlid fish species to extinction.

• Lesson for India: protect Indian wetlands (such as Loktak) using the Ramsar Convention's approach to wetlands.

• Fresh water as a strategic resource (GS-I/III): Baikal holds about 20% of the world's unfrozen fresh water [1]. As water becomes scarcer, protecting such stores matters for the whole world.

• Contrast with the Aral Sea, which shrank to about 10% of its 1960 size because of overuse for irrigation [2]. This shows how quickly a large lake can be lost through poor management.

• Value of World Heritage listing: UNESCO listing (1996) under all four natural criteria [1] is a global tool for protecting rare ecosystems. India can use the same tool for its own unique lakes and wetlands.

Related concepts

• Great Lakes of North America
• Caspian Sea
• Aral Sea
• Lake Victoria
• Lake Tanganyika
• Lake Chad

Read more

• Lakes and inland seas