China’s announcement that it has blocked the Xiabuqu river, a tributary of the Brahmaputra, to facilitate a hydroelectric project at Lalho in Tibet has again caused some concern in India. The Brahmaputra, known as Yarlung Tsangpo in Tibet, is a lifeline for Assam and Bangladesh where the river joins the sea. The dam is not far from the Indian border. The report attracted more attention because it appeared immediately after some statements in India about reviewing the Indus Waters Treaty with Pakistan. It was suspected that China was reminding India of its vulnerability on the eastern sector where the latter is the lower riparian country. But this does not seem to be the case because the construction of the dam had started in 2014 and the blocking of the water is according to a pre-determined schedule. But the concerns are not completely out of place in view of China’s known plans to harness the waters of the rivers in Tibet.

The Lalho dam is a run-of-the-river hydroelectric project and therefore may not reduce the water flow in the river. India’s main concern has been that the dams China is constructing in Tibet would reduce the availability of water downstream. Tibet is a source of major rivers, including the Mekong. The lower riparian countries of the Mekong also have similar fears. China has planned a series of dams on the plateau. It has already built one at Zangmu, and has proposed three other major dams on the Brahmaputra. It has been stated that none of them would reduce the water flow in the river. But there are other kinds of impact like the changes in the flow of silt. This has not been studied. In fact the Brahmaputra river system, or any other river system, has not been studied in detail over a period of time in India.

India has received assurances from China that its dams would not affect the flow of water in the Brahmaputra. But there is no water sharing and usage treaty between the two countries. There is an agreement on a mechanism for exchange of hydrological data and emergency management. But this is not enough, and India should take the initiative to work out a treaty with China, with Bangladesh also as a partner, which will form the legal basis for water sharing among all three countries. This is important because of persistent reports about China’s plans for diversion of waters from Tibet to its water-scarce regions. It is also necessary to ensure that the flow of water in the Brahmaputra is maintained in future in all situations.