In a world afflicted by climate change, a 60 GW clean energy hydroelectric project that can generate 300 billion kWhr of electricity is a mouthwatering proposition. But China’s Medog project on the ‘Great Bend’ of the Yarlung Tsangpo river — the upstream part of the Brahmaputra river — is being viewed with trepidation by India and several other countries. However, the unease is not so much over the project or its impact, but the fog over the project itself, even though it has been on the anvil for years. (The Chinese government formally approved the world’s biggest, $130 billion hydroelectric project in December 2024.) 

India has expressed its concerns, in a measured way, asking China to “ensure that the interests of the downstream states of the Brahmaputra are not harmed by activities in the upstream areas”. China, of course, insists it is executing the project responsibly, with no harm to the downstream countries — India and Bangladesh. 

Information available about the project is skimpy but, going by what is known so far, India may have little cause for worry. 

China says it is a run-of-the-river project, which typically impounds no (or very little) water — the force of the flowing river turns the turbines to produce electricity. But in the case of the Medog project (named after the region), it appears that there will be a dam. Nobody knows where exactly the dam will be built or, more importantly, how high it will be. 

A 2021 article in The Diplomat said (without attributions) that the dam would be 50-m high. If correct, then the Medog dam will be shorter than the 116-m Zangmu dam — also a run-of-the-river project — built further upstream on Yarlung Tsangpo, and commissioned in 2015. 

Unique bend

The Medog project takes advantage of a very unique geography. At the Great Bend, the east-flowing river makes a sharp U-turn at a point in the deep gorge before flowing south, just ahead of entering Arunachal Pradesh in India. 

The project involves drilling four tunnels, 20 km each, through the Namcha Barwa mountain cradled between the two arms of the U. This will channel some water through the steep tunnels, bypassing the bend and turning the turbines. The dam appears necessary to create a head of water and maintain the flow to the tunnels. 

If this is indeed what the project is all about, then it deserves a welcome (of course, leaving aside geopolitical issues such as China’s claim to Tibet).

Since China has not come out with the details (and given its assertive role in other regions such as the South China Sea, as also its approach to the other river system — the Mekong — with little concern for the lower riparians such as Vietnam), the Medog project is being frowned on. These concerns will ease only if the height of the dam and, consequently, the amount of water impounded are made public. 

India’s worry

A big worry is that the dam will diminish the flow of water into India — China may build a monstrous reservoir and divert the water to other parts of that country. Lt Gen Palepu Ravi Shankar, a former director general of Indian artillery, who hosts a podcast called Gunners Shot, fears that China may be intending to link Yarlung Tsangpo with the Yangtze, to water the Yunnan and other regions that are going dry due to climate change. Such a project would require a tall head of water, which is possible only with a high wall. Some worry that China may build a canal to take the Yarlung Tsangpo waters up north — a fear that Dr Nilanjan Ghosh, Director at the Observer Research Foundation, finds “irrational”. 

These apprehensions must be weighed against the fact that China, which has already constructed four dams across Yarlung Tsangpo, has not attempted to divert any water. 

Also, most experts have noted that the fear that water flow into the Brahmaputra will diminish is unfounded. The Yarlung Tsangpo becomes the Siang river when it enters India; it becomes the Brahmaputra after it is joined by the major tributaries Lohit and Subansiri. Roughly, at the Subansiri, only 30 per cent of the water is from China. Further down, the Brahmaputra is joined by some 50 tributaries, big and small. The northern tributaries are fed by melting Himalayan ice and the southern ones by the monsoon. China’s contribution to the Brahmaputra is not significant — the Chinese side of the Himalayas is the rain-shadow region and gets very little precipitation. Thus, apprehensions of China choking off water supply to India are baseless. 

Balanced approach

If at all there is a shortage of water, it could be in the 294-km Siang river. This, however, can be resolved if India gets ahead with the ambitious 11 GW Siang upper multipurpose project (SUMP) — said to be India’s response to Medog project. 

The SUMP would also serve as a protection if China were to weaponise the Yarlung Tsangpo by suddenly flooding water into India. 

Will the Medog project trigger earthquakes? This is a universal concern around any hydroelectric project, including those in India, such as the Tehri. If the Medog project does not impound large amounts of water, there is little to worry. 

Some have noted that the Medog may even be beneficial to India, helping with flood and silt control. 

In sum, unless some details of the project emerge and cue any ulterior motives on the part of China, India has no need to lose sleep over the Medog project. Indeed, it is good for all if it helps China decarbonise its economy.