China can choke Brahmaputra flow anytime: Warns river expert

Guwahati, May 30: India is at a huge disadvantageous position as far as water sharing with China goes, since both the countries do not have any water sharing treaty. India has only kept in abeyance the Indus Water Treaty (IWT) with Pakistan. Unlike the IWT, China being the upper riparian sitting in the driver’s seat, can choke the Brahmaputra river, internationally acclaimed river expert Prof Nayan Sharma has warned.

In an interview with The Assam Tribune, Prof Sharma, a former professor of IIT Roorkee and currently Professor of Excellence in Gauhati University, also suggested that India should proactively build numerous water storage infrastructure in all the major tributaries for sustenance of the country even if China decides to choke the Brahmaputra some day.

Following are excerpts from the interview:

Assam Tribune: India has kept in abeyance the IWT with Pakistan. But can China can also choke the water flow of the Brahmaputra river?

Prof Sharma: That is true. Unlike in the IWT, we are at a hugely disadvantageous position as the lower riparian country. You must be aware that China is going to build a super mega dam to generate a mindboggling 60,000 MW of hydropower at a huge outlay of USD 137 billion in the steep gradient of the Great Bend Canyon of the Yarlung Tsangpo or Brahmaputra river.

The Chinese are saying that it will be a hydropower project. But there is every possibility of China unilaterally diverting the stream flow, especially during the lean season which will choke India.

AT: But the Brahmaputra is also fed by its tributaries. Can the river sustain with water from the tributaries?

Sharma: The Brahmaputra receives a significant amount of its flow from tributaries. There are 33 major tributaries contributing to the major flow of the Brahmaputra. But the flow from the tributaries deplete in the lean season. The maximum discharge of the Brahmaputra at Pandu was recorded as 72,779 CUMEC on August 23, 1962, and minimum discharge was recorded as 1,757 CUMEC on February 22, 1968. Last year (2024) in July, the discharge was around 38,000 CUMEC. That means, there are very significant fluctuations in the water discharge from year to year and also from flood season to dry season. If China chokes the Brahmaputra, India will face a huge issue to fulfil the dry season water demand. The situation is highly alarming because India and China do not have a water sharing treaty.

As regards total water resources volume, only about 14 per cent of the Brahmaputra’s total annual water yield (AWY) is present in the river before it enters Indian territory from Tibet, with the remaining 86 per cent being contributed by rainfall and monsoon activity in India.

As regards water discharge value in CUMEC, in India, which accounts for 34.2 per cent of the Brahmaputra river basin area, it contributes the largest percentage of the total discharge, with an estimated 39 per cent.

Analysis on recent climate studies indicated that snowmelt contributed about 6 per cent of the total AWY volume of the whole Brahmaputra, 21 per cent of the upper Brahmaputra, and 5 per cent of the middle Brahmaputra. Due to ongoing global warming, the basin-wide average AWY is projected to increase by a whopping 8 per cent, with the maximum percentage increase in the pre-monsoon season.

Significantly, the annual snowmelt is projected to decrease by 17 per cent, with a marked decrease during the monsoon but an increase in other seasons and the greatest percentage reduction in the upper Brahmaputra (22 per cent). The contribution of snowmelt to AWY is projected to decrease, while runoff from rainfall will increase across the entire Brahmaputra.

The grim scenario emerging from the above estimates point to an increased reduction in the lean period Brahmaputra flows, whereas the pre-monsoon and monsoon season river flows are slated to rise – either way, it is worrisome. Such a very worrisome picture is further worsened multifold by positioning the Chinese super mega dam in the Yarlung Tsangpo Great Bend Canyon. There are two immediate fallouts (i) likelihood of acute water scarcity in the Brahmaputra Basin during the lean period, and (ii) very serious safety issues of all the bridge piers stability due to elevated climate-induced enhanced flood flows along with sizable excess water releases from the massive Chinese dam on the upper Brahmaputra. Besides bridge piers stability, this will increase flood vulnerability in the very narrow Brahmaputra Valley causing widespread inundation from innumerable flood embankment breaches.

AT: Can India put diplomatic pressure on China to sign a water sharing treaty?

Sharma: It is difficult. In fact, unilateral actions over transboundary rivers like the Sutlej and Brahmaputra by China are already causing unease between the riparian nations, which needs subtle conflict resolution with an interdisciplinary approach, since there is no ratified international law on transboundary rivers.

China is immune to world pressure and it has encountered rising water demand outstripping availability. Also, China has practically fully harnessed the water resources of its two main rivers – Yellow and Yangtse.

In the Yellow river, there are 10 large dams on the mainstream river, and over 3,100 smaller reservoirs throughout its basin. Similarly, a huge total of 43,400 dams have been built in the Yangtze river basin. The major cascade dams on the Yangtze include the Three Gorges Dam, Gezhouba Dam, Xiangjiaba Dam, Xiluodu Dam, and Baihetan Dam.

Now, for sustenance of economic growth and fulfilment of its GHG target, China urgently needs to make a paradigm shift to clean green power, including hydroelectricity, besides catering to growing multi-sectoral water uses. That is why China may not be readily amenable to enter into a water sharing treaty. Let me give one example – I was a Working Group member constituted by the United Nations University in Tokyo to explore associating China in the Mekong river studies. We participated in a specially focused workshop in China without receiving any positive outcome. Four of the six riparian countries of the Mekong river – Thailand, Laos, Cambodia and Vietnam – have joined hands to form the Mekong Committee for water sharing. But despite repeated attempts, China did not join the Mekong Committee. The UN also tried to persuade China to be a part of the committee. But it did not work, which proves that China is not readily amenable to listen to anyone.

AT: What is the way out then?

Sharma: In my well-considered view, a top priority way out is urgent construction of numerous medium to low-height water storage infrastructure on war-footing on the tributaries of the Brahmaputra to store water during the rainy season for use in the lean season. If we can do that, we will become immune to any Chinese attempt to choke the Brahmaputra. Let me clarify that I am not talking about any huge mega dams but numerous smaller storage dams in the hundred-odd tributaries of the Brahmaputra. Ending on an optimistic note, my take is – as a starting point, subtle diplomatic processes may be initiated for forging water sharing agreement for the Brahmaputra among the four riparian nations, China, India, Bhutan and Bangladesh, which may gradually thaw the ice some day. Such an initiative may be founded on the ‘benefit sharing’ principle that transboundary river cooperation offers benefits such as access to external markets, leading to economies of scale (e.g., lower marginal cost of unit hydropower production); avenues of building on collaborative mode, (e.g. in irrigation, hydropower); improved management and coordinated operation of infrastructure for multipurpose water uses; possibility of joint action on common global threats, (e.g., climate risks, floods & malaria).