The dam over the Brahmaputra being constructed by China has evoked an outcry in India, and especially in its Northeast, as reported by the local media. This article presents an overview of opinions and facts that emerge from the debate. According to reports, China is building a hydroelectric dam in Zangmu Tibet, which may divert the Tsangpo River, the source river of the Brahmaputra. The lack of an international water-sharing treaty between India and China and previous statements by the Chinese leadership raise suspicions that the construction of the dam may divert the water. This dam will be a lifeline for the Yellow River in dealing with water shortages in the densely populated eastern seaboard of China. The Government of India through Foreign Secretary Nirupama Rao said it had received assurances from the Chinese Vice-Foreign Minister Zhang Zhijun that the project was not diversionary but purely power-generating and a run-of-the-river hydro project, which would not affect the water availability to the lower riparian states.

Notwithstanding China’s lack of assurances, the Zangmu Dam may eventually impact the flow of water, which has been highlighted in a Guwahati portal titled China wants to divert Brahmaputra where the president of the NGO Jana Jagriti, Ashokanand Singhal, has claimed that the construction of the dam has already reduced the flow as compared to previous years. The Brahmaputra used to provide 78.1 billion cubic metres (bcm) of water during the monsoons in India and 56.12 bcm on non-monsoon days, but the river flow has been reduced by 30% during the monsoons and provided only 60 per cent the rest of the year. It has been also highlighted that when the project will be completed, the river Brahmaputra will be left with only 20 per cent of its present water-flow capacity.

An interesting argument has been presented by expert who have concentrated on the primary water catchment areas being on the Indian rainward side. A senior geologist of Guwahati University opined that diversion of the Brahmaputra will adversely affect ground water replenishment since the base level of the river would go down, spelling disaster for a largely agricultural state like Assam, especially communities’ dependant on wells. Every summer the aquifers are recharged by the river which in winters, release into the river maintaining its robust flow. Decrease in flow, he reasoned, would result in reduction in flushing efficiency and increase sediment deposits destroying the fragile riverine ecosystem. Though ground water utilization in Assam is at present less than 20 per cent, population increase combined with diminishing ground waters, increased silting and consequent reduction of cropland create a whole new set of problems. Putting the nature of the Brahmaputra’s flow in context - at Pasighat lean flow is around 2,000 Cusec, while peak flow is around 20,000 Cusec - a very big range, is especially important. This expert wondered how the government had taken China’s word without studying the bed form morphology using high-resolution satellite photography, and intensive data collection on the river’s flow using digital data loggers.(Diversion may hit State ground water, The Assam Tribune, 16 Jun 2011).

To stem the flow of cynicism, External Affairs Minister SM Krishna clarified that while the construction phase would temporarily affect the flow of one channel of the Tsangpo, the other two channels of the same river would continue to flow unimpeded. "There is no diversion as yet confirmed through satellite imagery and other information. However, they are constructing smaller dams on tributaries of the Brahmaputra, but these too are run-of-the-river projects.”  He was thus insisting that this latest clean chit to China was backed up by hard evidence (Centre allays fear on Brahmaputra China dam issue, The Assam Tribune, 17 Jun 2011). The former Union Minister for Development of North Eastern Region BK Handique reiterated the GoI’s assurance but also added, “I do not know about the future.” (Handique allays fears over Brahmaputra diversion, The Shillong Times, 3 July 2011).

J P Rajkhowa, a former Chief Secretary of Assam stated that China cannot be trusted, since precedents dictate that official Chinese denials only prove the crime. (Counter China’s Move on the Brahmaputra, The Sentinel, 9 Jul 2011) Echoing this sentiment, Singhal said, "China does not even share water-data with India," urging a hard line – including hauling China to international fora if necessary. (Gogoi urged not to buy Krishna’s version, The Assam Tribune, 17 Jun 2011) Ajum, spokesperson of the All Arunachal Pradesh Student's Union (AAPSU) said, "The matter now lies entirely with New Delhi. They should take it seriously rather than dithering on this sensitive issue. (India keeping watch on China's Brahmaputra plans: Pala, The Assam Tribune, 14 June 2011). The Sentinel was of the opinion that GoI must change its approach given China’s antecedents and should deal with the issue intelligently and confidently. (Brahmaputra concern, The Sentinel, 16 Jun 2011). Assam Chief Minister Tarun Gogoi was of the opinion that while China has the liberty to build a dam it must not affect lower riparian states, putting forward a case for a formal water sharing agreement (The downstream effect of the dam is our immediate concern, Tehelka, 14 Dec 2010).

The overarching impression gleaned from this survey is that the controversy has two major roots: the lack of a water-sharing treaty with China and a paucity of facts and in-depth long term studies. Till both these are addressed, the situation will only continue to fester.