There is also the Precautionary Principle: one should refrain from a major intervention in nature unless one knows what the consequences will be and whether they will be acceptable. It is not for the critics to prove that the project will cause harm to the ecological system; it is for the proponents to prove that it will not.

On the social and human aspects, it is necessary to examine whether the project will have an impact on the livelihoods of fisherfolk in the area, as has been claimed; the people concerned seem to be very worried, and their concerns will have to be gone into.

Finally, some critics have raised security concerns, and Sri Lanka is reported to have reservations on this project, but we may leave those aspects to the government. They may not be within the scope of the Pachauri panel.

Let us return to the crucial question. If the project will have serious ecological and social costs, and if there are substantial doubts about the economic viability of the channel, then why is it being built? That is the question to which we need an answer.

The writer is an expert on water resources and an honorary research professor at the Centre for Policy Research express@expressindia.com