Mekong

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

Meaning

The Mekong is a great river of Asia. It rises on the Tibetan Plateau and flows through China (where it is called the Lancang), then Myanmar, Laos, Thailand, Cambodia and Vietnam. It ends in the South China Sea through a large delta in southern Vietnam.

It matters because millions of people depend on its fish and fertile silt. Chinese dams upstream are now changing how the river floods. India works with the Mekong countries through the Mekong–Ganga Cooperation [1][2].

Explanation

Course: from Tibet to the South China Sea

• Source: the Tibetan Plateau, the high land north of the Himalaya.
• Upper course: it flows through China, where its name is the Lancang.
• Middle course: it flows past or through Myanmar, Laos and Thailand, then into Cambodia.
• Lower course: it crosses southern Vietnam and splits into many distributaries (branches that leave the main river near its mouth).
• Mouth: it reaches the South China Sea through a large delta. A delta is a low, flat landform the river builds at its mouth by dropping its silt.
• Six countries in all, from upstream to downstream: China → Myanmar → Laos → Thailand → Cambodia → Vietnam.

Monsoon regime: one big flood each year

• The regime of a river is the pattern of its flow through the year.
• The Mekong is a monsoon river. It has one big flood season and one low-water season.
• Rainy season (June–November): monsoon rain makes the river rise very high.
• Dry season: the river falls and carries much less water.
• This yearly rise and fall is called the flood pulse. It spreads water, fish and fertile silt over the lowlands.

Tonle Sap: the lake whose river runs backwards

• Cause: in the rainy season the Mekong rises far above its normal level.
• Process:
• The high Mekong pushes water up the Tonle Sap River into Tonle Sap Lake in Cambodia.

• So the Tonle Sap River reverses its flow [3].

• Result: the lake grows about three times bigger, from about 3,000 km² to about 10,000 km² [3].

• Dry season: the river turns round again and drains the lake back into the Mekong.
• Why it matters:
• Tonle Sap is the largest freshwater lake in Southeast Asia [4].
• It supports over 3.6 million people [4].
• Fish breed in the flooded forests and fields around it.

Upstream dams and who manages the river

• Chinese dams on the Lancang:
• They hold back water and silt.
• This weakens the flood pulse that fills Tonle Sap.

• Result: fewer fish and less fertile silt reach Cambodia and Vietnam.

• Three bodies deal with the river:

Body	Year	Members / leader	Key point
Mekong River Commission (MRC)	1995	Cambodia, Laos, Thailand, Vietnam	China is not a member
Lancang–Mekong Cooperation (LMC)	2016	China-led, with the five Mekong countries	China's own framework
Mekong–Ganga Cooperation (MGC)	2000	India + Cambodia, Laos, Myanmar, Thailand, Vietnam	Launched at Vientiane, Laos [1][2]

Where it occurs

• China (Lancang): upper course. It starts on the Tibetan Plateau. The upstream dams are here.
• Myanmar, Laos, Thailand: middle course. Laos's capital Vientiane sits on the Mekong, and the MGC was launched there [1][2].
• Cambodia: Tonle Sap Lake and the Tonle Sap River, which reverses its flow in the rainy season [3].
• Vietnam: the Mekong delta in the south, where the river enters the South China Sea.
• India's link: India is not on the Mekong. It joins the region through the Mekong–Ganga Cooperation (2000). That group has 6 members: India + Cambodia, Laos, Myanmar, Thailand and Vietnam [1].

Don't confuse with

• Salween: it also rises in Tibet, but it runs along part of the Myanmar–Thailand border and ends in the Andaman Sea. The Mekong ends in the South China Sea.
• Irrawaddy: it flows through Myanmar only and ends in the Andaman Sea. The Mekong crosses six countries.
• Yangtze (Chang Jiang): it also starts on the Tibetan Plateau, but it stays in China. It ends in the East China Sea near Shanghai and is Asia's longest river. The Three Gorges Dam is on the Yangtze, not the Mekong.
• Mekong River Commission vs Lancang–Mekong Cooperation vs Mekong–Ganga Cooperation: the MRC (1995) leaves out China. The LMC (2016) is led by China. The MGC (2000) is the group that includes India.

Prelims Hooks

• Mekong course: Tibetan Plateau → China (Lancang) → Myanmar → Laos → Thailand → Cambodia → Vietnam → South China Sea. Trap: it does not end in the Andaman Sea or the Bay of Bengal.
• Tonle Sap (Cambodia): its river reverses flow in the rainy season (June–November). The lake grows from about 3,000 km² to 10,000 km² [3]. It is the largest freshwater lake in Southeast Asia [4].
• Mekong River Commission (1995): Cambodia, Laos, Thailand, Vietnam. China is not a member.
• Lancang–Mekong Cooperation (2016): China-led.
• Mekong–Ganga Cooperation (2000, Vientiane): 6 members, India + Cambodia, Laos, Myanmar, Thailand, Vietnam [1]. Trap: China is not a member.
• Monsoon river: the Mekong has one big flood season, like the Blue Nile. The Amazon and Congo are equatorial rivers that flow high all year.

Mains Points

• The Mekong follows the usual upstream–downstream conflict pattern:
• Upstream China builds dams on the Lancang for hydropower (electricity made by water turning turbines).
• Downstream Cambodia and Vietnam lose water, silt and fish.
• The same pattern appears with the Nile (GERD vs Egypt and Sudan) and the Tigris–Euphrates (Turkey's GAP vs Syria and Iraq).

• Lesson for India: on the Brahmaputra (with China), India needs basin bodies that share data and include every riparian (country along the river). The MRC is weak because China stays out (GS-I/GS-II).

• Dams trade clean energy against river health:

• They weaken the natural flood pulse, so Tonle Sap fish stocks fall [3][4].
• They trap silt, so less fertile soil reaches farms and the delta.

• People who live from fishing and farming, over 3.6 million around Tonle Sap alone [4], lose their income (GS-III environment).

• Rivers as tools of diplomacy: the Mekong–Ganga Cooperation [1][2] links India's Ganga region with the Mekong countries. It supports India's Act East policy and works alongside China's LMC (GS-II/GS-I).

Related concepts

• Nile
• Grand Ethiopian Renaissance Dam
• Congo River
• Victoria Falls
• Amazon
• Danube
• Tigris-Euphrates river system

Read more

• Great rivers and their basins