Yarlung Tsangpo

Also called: Tsangpo · Topic: Drainage System of India: Rivers, Basins and Patterns · NCERT: Class 11, Ch 3 "Drainage System"

Meaning

The Yarlung Tsangpo (or Tsangpo) is the name of the Brahmaputra in Tibet. It runs from the Chemayungdung glacier near Lake Mansarovar, flows east for about 1,200 km through dry southern Tibet, and then turns sharply around Namcha Barwa at the Great Bend. After that it enters India as the Siang. "Tsangpo" means "the purifier".

It matters for two reasons. It is the upper part of one of India's three great Himalayan river systems. China is also building a mega dam on its lower stretch, which raises water-security concerns for India [3].

Explanation

Origin and course in Tibet

• Source: the Chemayungdung glacier of the Kailash range, near Lake Mansarovar in south-west Tibet (about 30–31°N). The source is at about 5,150 m [2].
• Direction: it flows east for about 1,200 km, parallel to the Himalaya.
• Landscape: it crosses dry, flat southern Tibet.
• This is a rain-shadow area (a dry area on the far side of a mountain).
• The Himalaya block the wet monsoon winds, so little rain falls here.

• In this stretch the river is calm and slow.

• Main right-bank tributary in Tibet: the Rango Tsangpo.

The Great Bend and the gorge

• Where: near Namcha Barwa (7,755 m), the eastern anchor of the Himalaya, close to Medog in Tibet.
• What happens:
• The calm river becomes turbulent (fast and rough).
• It turns sharply around the peak in a U-turn called the Great Bend.

• It cuts a very deep, narrow gorge.

• Why it can cut such a gorge:

• The river is older than the rising mountains, so it kept its old path while the land rose.
• It drops steeply from the high Tibetan Plateau towards the plains.
• The steep drop gives the water great power to cut down into the rock.

Change of names, from source to sea

Stretch	Name of the river	Direction
Tibet (Chemayungdung glacier to the Great Bend)	Tsangpo / Yarlung Tsangpo	East
Arunachal Pradesh foothills	Siang / Dihang	South (through the gorge)
After the Dibang and Lohit join, through Assam	Brahmaputra	South-west, then west
Bangladesh, after the Tista joins	Jamuna	South
After meeting the Padma	Padma	To the Bay of Bengal

• The whole river is about 2,900 km long and flows through Tibet (China), India and Bangladesh [2].
• How the Tibetan stretch fits into the bigger picture:
• The Indo-Brahma hypothesis says one huge river once flowed along the whole Himalaya, from Assam to Punjab.
• Uplift of the western Himalaya and the Potwar Plateau broke it into the Indus, Ganga and Brahmaputra systems.
• The Tsangpo is the Tibetan head of the Brahmaputra system.

Water supply and the trans-border dam

• Snowmelt feeds it in summer: melting snow and glaciers in Tibet make the river swell. In India, monsoon rain adds to this peak, which makes the system perennial (it flows all year).
• China's mega dam:
• China approved a mega dam on the lower Yarlung Tsangpo, which is the upper Brahmaputra [3].

• It is near the Great Bend (Medog), about 60 GW in size, and construction began in July 2025.

• India's response:

• India registered its concerns with China on 30 December 2024 and asked for transparency and consultation with downstream countries [3].
• India raised the issue again at the Foreign Secretary–Vice Foreign Minister meeting in Beijing on 26–27 January 2025 [3].
• Both sides agreed to hold an early meeting of the Expert Level Mechanism to discuss restarting the sharing of hydrological data (river level and flow data) [3].

Where it occurs

• South-west Tibet: the source is the Chemayungdung glacier, Kailash range, near Lake Mansarovar.
• Southern Tibet: the dry, flat rain-shadow belt along which the river flows east for about 1,200 km.
• Eastern Tibet: the Great Bend around Namcha Barwa (7,755 m), near Medog, which is also the site of China's ~60 GW dam.
• Arunachal Pradesh, India: the river comes out of the foothills as the Siang (Dihang) and enters the plains west of Sadiya.
• India's planned Siang Upper Multipurpose Project (about 11,000 MW) is here.
• "Multipurpose" means it would serve several uses: power, water storage and flood control.
• Its reservoir would act as a buffer (a store of water) against sudden releases from upstream.
• The Upper Siang Project is listed at the pre-feasibility and project-development stage [4]. A pre-feasibility study is an early check of whether a project is worth building.
• The Adi community opposes it locally because land and villages would be flooded.

Don't confuse with

• Siang / Dihang: this is the same river after it leaves the Great Bend gorge and enters Arunachal Pradesh. The Tsangpo is the Tibetan stretch only.
• Rango Tsangpo: this is a right-bank tributary of the Yarlung Tsangpo in Tibet, not the main river.
• Brahmaputra ("son of Brahma"): the river gets this name only after the Dibang and Lohit join the Siang, near Sadiya. "Tsangpo" means "the purifier".
• Subansiri: it also rises in Tibet, but it is a separate antecedent tributary (a river older than the mountains it cuts across). It joins the Brahmaputra on the right bank in Assam.

Prelims Hooks

• Source: Chemayungdung glacier → Kailash range → near Mansarovar → about 5,150 m [2].
• Meaning trap: "Tsangpo" = "the purifier". "Brahmaputra" = "son of Brahma".
• Order of names: Yarlung Tsangpo (Tibet) → Siang/Dihang (Arunachal) → Brahmaputra (Assam) → Jamuna (Bangladesh) → Padma → Bay of Bengal.
• Great Bend: the river cuts a gorge round Namcha Barwa (7,755 m), near Medog.
• Tributary bank trap: Rango Tsangpo is a right-bank tributary in Tibet. Dibang (Sikang) and Lohit are left-bank tributaries in Arunachal.
• Current affairs: India raised concerns about China's dam on the lower Yarlung Tsangpo on 30 December 2024. The Expert Level Mechanism handles hydrological data sharing [3].

Mains Points

• Physical geography of the Tibetan stretch (GS-I):
• The rain-shadow position explains the dry, calm upper course.
• The steep drop off the plateau and the river's age explain the deep Great Bend gorge.

• Snowmelt from Tibet, added to monsoon rain in India, causes the summer flood peak downstream.

• Trans-border water security (GS-II/GS-III):

• China's ~60 GW Medog dam lets an upstream country control when water flows.
• Risks for India are lower dry-season flow, sudden releases or dam failure flooding Arunachal and Assam, and high earthquake risk in the region.

• India's response has two parts: diplomacy (concerns raised, Expert Level Mechanism [3]) and the Siang Upper storage project as a buffer.

• Development versus displacement (GS-III):

• The Brahmaputra basin holds about 37% of India's hydropower potential (31,012 MW) [2].
• Projects like Siang Upper must weigh energy and flood control against displacing the Adi community, earthquake risk and harm to river ecology.

Related concepts

• Brahmaputra river
• Siang river
• Subansiri river
• Tista river

Read more

• The Brahmaputra system