Caspian Sea

Geography glossary

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

Meaning

The Caspian Sea is the world's largest inland water body, about 371,000 sq km. It is a saltwater lake in a closed basin, about 28 m below sea level. Five countries border it: Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan.

It matters for three reasons. It holds oil, gas and sturgeon. The five states argued for years over whether it is a "sea" or a "lake". And its water level is now falling.

Explanation

Why it is a lake and not a sea

  • Lake: a large body of water that sits in a hollow in the land, with land all around it. The Caspian has land on every side, so it is a lake.
  • Inland sea: a very large lake with salt water, or a sea that is almost cut off from the ocean. The Caspian is the standard example.
  • Why people call it a "sea":
  • It is very large.

  • Its water is salty, like sea water.

  • Trap: it is the largest inland water body. It is not the largest freshwater lake. That record belongs to Lake Superior.

How it became salty

  • Endorheic (closed) basin: a basin with no outlet to the ocean.
  • Cause: rivers flow into the Caspian, but no river flows out to the ocean.
  • Process: water leaves only by evaporation (turning into vapour in the heat). The salts the rivers bring in stay behind.
  • Result: over a long time, salts build up and the lake turns saline (salty).
  • Its surface is about 28 m below sea level. It sits in a low hollow, so water flows into it and cannot drain out.

Where its water comes from

  • Volga: brings most of its water. This is the key lake–river pair.
  • Ural and Kura: two smaller rivers that also flow in.
  • The level depends on a balance:
  • Water in: river inflow.
  • Water out: evaporation.
  • If inflow falls or evaporation rises, the level drops.

Resources and legal status

  • Oil and gas: around Baku (Azerbaijan) and in the Kazakh fields.
  • Sturgeon: a fish whose eggs are sold as caviar.
  • The "sea or lake" question:
  • If it is a "sea": the UN law of the sea would divide it.
  • If it is a "lake": the five states would divide it equally.
  • Outcome: in 2018 the five states signed the Aktau Convention. It gives the Caspian a special status of its own, neither a plain sea nor a plain lake.

Where it occurs

  • Location: western Asia, on the border between Europe and Asia, east of the Caucasus Mountains.
  • The 5 littoral states (countries with a coast on it):
  • Russia: on the north-west, where the Volga flows in.
  • Kazakhstan: on the north and north-east, where the Ural flows in. It has oil and gas fields.
  • Turkmenistan: on the east.
  • Iran: on the south.

  • Azerbaijan: on the west. Its capital Baku is an oil centre. The Kura flows into the lake here.

  • Other closed basins in the world: the Aral Sea, Dead Sea, Great Salt Lake and Lake Chad also have no outlet to the ocean.

  • India: India has no part of the Caspian. India's shrinking lakes, such as Sambhar and Loktak, are useful comparisons for falling water levels.

Don't confuse with

  • Lake Superior: the largest freshwater lake by area (about 82,100 sq km) [2]. The Caspian is the largest inland water body, and it is salty.
  • Aral Sea: also a salty lake in a closed basin, but it lies on the Kazakhstan–Uzbekistan border. It is fed by the Amu Darya and Syr Darya, not the Volga. It shrank to about 10% of its 1960 size because river water was taken to irrigate cotton [1].
  • Dead Sea: the lowest point on land, about 430 m below sea level, on the Jordan–Israel/West Bank border, fed by the Jordan River. The Caspian is only about 28 m below sea level.
  • Lake Baikal: the deepest and oldest lake. It is a freshwater rift lake (a lake in a strip of land that sank between two cracks in the crust) in Siberia, Russia. The Caspian is a saltwater lake in a closed basin.

Prelims Hooks

  • Largest inland water body: Caspian (about 371,000 sq km). Largest freshwater lake by area: Superior.
  • Lake–river pair: Caspian–Volga (main feeder). The Ural and Kura also flow in.
  • 5 littoral states: Russia, Kazakhstan, Turkmenistan, Iran, Azerbaijan. Trap: Uzbekistan, Armenia and Georgia do not touch the Caspian.
  • Aktau Convention (2018): settles the legal status of the Caspian Sea by giving it a special status of its own.
  • Classification: a saltwater lake in an endorheic (closed) basin, about 28 m below sea level. Water leaves only by evaporation.
  • Resource matches: Baku (Azerbaijan) – oil and gas; sturgeon – caviar.

Mains Points

  • Falling water level (GS-I/III):
  • Causes: less water arrives from the Volga, and more water evaporates as the climate warms.

  • Lesson: a closed lake depends fully on what rivers bring in. The Aral Sea shows how badly things go when that inflow is cut. India should manage whole river basins and water demand, not just supply. Sambhar and Loktak are the lakes to watch.

  • Shared lakes need shared rules (GS-I/II link):

  • The "sea or lake" question decided who gets the oil, gas and fish. The Aktau Convention (2018) settled it.

  • Like the Great Lakes (International Joint Commission) and Lake Chad (Lake Chad Basin Commission), the Caspian shows how countries can manage a shared lake together. This is useful for India's shared river waters.

  • Resources and environment (GS-III): the Caspian gives oil and gas (Baku, Kazakh fields) and sturgeon for caviar. Drilling for energy has to be balanced against protecting fish in a shrinking, salty lake.

Related concepts

Read more

Sources

  1. 1Aral Sea, Kazakhstan and Uzbekistan — USGS EROS Earthshotseros.usgs.gov · tier 2
  2. 2Areas and Volumes of the Great Lakes — Britannicabritannica.com · tier 3