Aral Sea

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

Meaning

The Aral Sea is a saltwater lake in a closed basin on the Kazakhstan–Uzbekistan border. It was once about 68,000 sq km, the 4th-largest lake in the world [1]. Since the 1960s it has shrunk to only about 10% of its 1960 size [1], because Soviet projects took water from its two feeder rivers, the Amu Darya and Syr Darya, to grow cotton.

It is one of the world's worst human-made environmental disasters. UPSC uses it as a classic case of poor water management, along with Lake Chad.

Explanation

Why the Aral is a closed lake

• The Aral Sea sits in an endorheic (closed) basin. This is a basin with no outlet to the ocean.
• How water comes in: almost all of it comes from two rivers:
• the Amu Darya

• the Syr Darya

• How water goes out: only by evaporation, because no river flows out to the sea.

• What this means:
• When water evaporates, the salt stays behind. Over time the lake becomes saline (salty).
• The lake stays the same size only while inflow from the rivers equals the water lost to evaporation.
• If inflow falls, the lake shrinks and gets saltier.

How the sea shrank (cause → process → result)

• Cause: river water was taken for cotton
• From the 1960s, Soviet projects took water from the Amu Darya and Syr Darya.

• The water went to irrigate cotton fields in the dry lands of Central Asia.

• Process: evaporation became greater than inflow

• Much less river water reached the sea.
• In this dry region, evaporation went on as before.

• So the sea lost more water each year than it received.

• Result: the sea shrank and split

• The sea is now only about 10% of its 1960 size [1].
• It has split into two parts: the North Aral (in Kazakhstan) and the South Aral [2].

Effects of the drying

• Aralkum desert: the dry seabed has become the Aralkum, a new toxic desert.
• Poisonous dust storms: winds lift salt and pesticide dust from the old seabed and carry it over nearby land and towns.
• Loss of livelihoods: fishing towns that once stood on the shore collapsed.
• Health and migration: the toxic dust harms people's health, and people leave the region to find work.

Partial recovery and its trade-off

• Kok-Aral Dam (Kazakhstan):
• Completed in 2005, it holds water back in the North Aral [2].

• It replaced an earlier dike built in the 1990s [2].

• Good result in the North:

• By 2011, the North Aral's salinity was back to its 1960s level of about 8 g per litre [2].

• Its fisheries have recovered [2].

• Cost in the South:

• The dam lets less water flow on to the south.
• So the South Aral keeps shrinking and getting saltier [1][2].

Where it occurs

• Location: Central Asia, on the Kazakhstan–Uzbekistan border [1].
• Feeder rivers: the Amu Darya and the Syr Darya. Their water was diverted for cotton irrigation.
• Present parts:
• North Aral: in Kazakhstan. It is held back by the Kok-Aral Dam (2005) and is recovering [2].

• South Aral: it is still shrinking and getting saltier [1][2].

• Aralkum: the new toxic desert on the dried seabed.

• A similar case in the world: Lake Chad in the Sahel (Chad, Cameroon, Niger, Nigeria) has also shrunk by more than 90% since the 1960s [3].
• Lesson for India: shrinking lakes such as Sambhar and Loktak show the same risk. Both need basin-level planning and control over how much water is used.

Don't confuse with

• Caspian Sea: the world's largest inland water body (about 371,000 sq km), fed mainly by the Volga. It is shrinking mainly because the Volga brings less water and a warming climate raises evaporation. The Aral shrank mainly because people diverted its rivers for cotton.
• Lake Chad: it also shrank by more than 90%, but the main cause was less rain where its feeder rivers, the Chari and Logone, begin [3]. Irrigation was only a secondary cause. The Aral's main cause was irrigation diversion.
• Lake Balkhash: also in Kazakhstan, fed by the Ili River. It is half fresh (west) and half salty (east). The Aral is not divided this way. It split into a North and a South part because it shrank.
• North Aral vs South Aral: the Kok-Aral Dam (2005) saved the North Aral (Kazakhstan). It did not save the South Aral, which is still drying.

Prelims Hooks

• Aral Sea – feeder rivers: Amu Darya and Syr Darya (not the Volga, which feeds the Caspian).
• Location: Kazakhstan–Uzbekistan border. It was once the 4th-largest lake in the world, at about 68,000 sq km [1].
• Cause of shrinking: Soviet diversion of river water for cotton irrigation from the 1960s. The sea is now about 10% of its 1960 size [1].
• Trap: the Kok-Aral Dam (2005) is in Kazakhstan and saved the North Aral, not the South Aral [2].
• Aralkum is the toxic desert that formed on the dried bed of the Aral Sea.
• Classification: the Aral is an endorheic (closed) basin lake, like the Caspian, the Dead Sea, the Great Salt Lake and Lake Chad.

Mains Points

• Human-made drying (GS-I/III): taking too much river water for cotton made the Aral Sea shrink to about 10% of its 1960 size [1].
• Effects: toxic salt-and-pesticide dust storms from the Aralkum, collapse of fisheries, harm to people's health, and migration.

• Lake Chad (drought plus irrigation) shows the same pattern of about 90% shrinking, with food insecurity and the growth of Boko Haram.

• Recovery is possible but has trade-offs: the Kok-Aral Dam brought salinity in the North Aral back to about 8 g per litre by 2011 and revived its fisheries [2]. The South Aral was left to keep drying [1][2]. Restoration often means choosing which part to save.

• Lesson for India (GS-III): plan for whole river basins and control the demand for water, not just the supply. Shrinking lakes such as Sambhar and Loktak need this approach before they reach an Aral-like state.

Related concepts

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

Read more

• Lakes and inland seas