Will China wage a water war against India? For many, China's dam building on the Brahmaputra river evokes the image of a tap that can be turned off at will, leaving millions in Arunachal Pradesh, Assam and Meghalaya thirsting for water by the drying banks of the mighty river. Strategists have argued that this is a real possibility, and one has even written a sci-fi book on it.
The scare reemerged on 1 October when China announced it had blocked a tributary of the Brahmaputra for a dam it has been constructing since 2014. Since this happened within a day of India's "surgical strikes" in Pakistan Occupied Kashmir and murmurs of damming the Indus, the imagery of a water war seemed appropriate.
But can such a war really happen? Fortunately, there is no unanimity on this view.
Experts with knowledge of the river, and of India-China relations, say China's power over the Brahmaputra is exaggerated. There just isn't that much water in the Brahmaputra on the Chinese side as to cause largescale devastation downstream. As for damage from China's damming the river, there are far more dams on the Indian side that can cause greater damage. Indeed, in the downstream areas of Assam, there is greater reservation against India's dams on the river than the Chinese ones, which are fewer in number.
How much water can China control?
The Brahmaputra originates in the Tibetan plateau, where it is known as the Yarlung Tsangpo. Running eastward for about 1,100 km through a dry region, the river makes a dramatic U-turn at the Great Bend, and flows southward into Arunachal, where it is known as Siang. From there, a great volume of water is added to the river by its tributaries such as the Dibang, Subansiri, Lohit and Kameng in India, and the Teesta in Bangladesh.
In fact, far more water is added to the Brahmaputra's flow in India, Bhutan and Bangladesh than in China. According to the Food and Agriculture Organisation's AQUASAT survey of 2011, the annual flow of the Brahmaputra basin from China to India is 165 cubic kilometre, but from India to Bangladesh the flow is 537 cu km. Bhutan alone discharges 78 cu km - half of China's amount - into the river.
According to another study, although 50% of the Brahmaputra basin is in China, it generates just about 22% of the annual water discharge of the river because of the dry weather there. India accounts for 34% of its basin area but contributes 39% of the total discharge. Bhutan covers 6.7% of basin but 21% of the discharge, almost the same as China.
This is why most experts dismiss the fear that China will someday choke the Brahmaputra water supply to India. "There is no question of the Chinese controlling the water flow in the Brahmaputra since most of the water comes from Indian tributaries, that is the monsoon rainfall. The water flow issue is quite overstated and a result of ignorance and prejudice acting together," says Jabin Jacob, fellow at the Institute of Chinese Studies.
Moreover, China has little capacity to hold the water back. The dam on the river it operationalised last year - Zangmo or Zam dam - is a 510 megawatt run-of-the-river dam that doesn't take out any water from the river. The other dams proposed on the river are also of this type.
In fact, the dam for which China blocked a tributary recently - and which has sparked the latest fear of water wars - is Lalho Hydroelectric Project, the first storage reservoir for irrigation; the first dam, that is, which will actually take water out of the river. But this tributary - Xiabuqum - contributes only about 0.02% of the Brahmaputra's flow in China.
Since the other dams aren't of the storage type either, China does not yet have the capacity to block water during the lean season in India, when the Chinese share of water in the river is much higher.
If not dams, then what?
If it is not damming the river, then the fear is that China will divert the Brahmaputra to its drier regions. However, such a plan has never taken off, mostly because it is too expensive as it entails pumping water to a height of over a thousand metres across the Tibetan plateau and into northern China. This, obviously, poses major technological and environmental challenges.
In a recent paper, Hongzhou Zhang of the Institute of Defence and Strategic Studies at the Nanyang Technological University, Singapore, argues that the river diversion project is "highly unlikely" because of the engineering and economic costs.
"It would be staggeringly expensive and complex to divert the Brahmaputra to northern China, even for China, a powerful country that has demonstrated its penchant for heroic engineering. The costs in energy and finance of a project that would involve crossing the upper reaches of the Salween, the Mekong and the Yangtze en route are almost incalculable," he writes.
Real threat is from both sides
The real threat of the Chinese dams is ecological. Huge ecological costs are attached to even run-of-the-river projects - although they return water to the river, they harm aquatic life and also take out silt from the river, which harms agriculture downstream. Such dams are also prone to manipulating the water flow in the river to suit power demand, which can wreak havoc on the river's ecology and cause floods.
And if this is the only threat, then India is its own biggest enemy. No less than 168 dams are proposed to be built in the Brahmaputra basin in India. "The ecological damage is much more serious on our side. Many of these dams are being pushed without proper environment impact assessments," Jacob of the ICS says.
Such bumper-to-bumper dams have also been alleged to compound the impact of floods, such as the one in Uttarakhand in 2013 which was trigerred by a cloudburst and claimed thousands of lives.
So, in Assam, which is downstream to these dams, there is more opposition to Indian dams in Arunachal than Chinese dams in Tibet. Bangladesh, which is further downstream, has similar concerns.
"A cursory glance through local newspapers would show there is more talk about Indian than Chinese dams," says Mirza Zulfiqur Rahman, senior research fellow at IIT Guwahati. He says concern for dams in Arunachal "significantly overrides" that for the Chinese ones, not just because there is lesser information about the latter but also because a large population in Assam is already feeling the pinch. "Only one or two dams have started operations, and that alone is causing rivers to go dry."
India has been building dams as a strategic measure - both to strengthen its claim on Arunachal, which China claims as its own, and to exercise "first use" rights over the river, which can give it weight in international fora in case China decides to block the Brahmaputra.
But since the real threats from damming the river - ecological and human costs - come from both Indian and Chinese sides, it isn't knee-jerk reactions to fear of water wars that is required, but cooperation. While steps have been taken on sharing information on river water levels, these are just baby steps.
"The point is that all this is happening in a high altitude area vulnerable to disasters, which would get compounded with the presence of dams. There needs to be a cumulative impact assessment done jointly. China should share more information, which it hasn't so far," says Himanshu Thakkar, coordinator at South Asia Network on Dams, Rivers and People.
"The Lalho dam information came now even though the construction began in 2014. Either China didn't share information with India, or it did and India didn't make it public," Thakkar adds. "Either way, it is the people who will face the music."