For four decades now, India has put its weight behind river interlinking projects that transfer excess water from one river basin to the other — a $168 billion answer to a swelling water stress crisis. Prime Minister Narendra Modi in 2020 said projects like the Ken-Betwa link have “huge potential to change the fate” of the regions they touch; other ministers called them a ‘permanent’ solution to droughts.
A new study published in Nature Communications, however, challenges these claims: many hydro-linking projects in India and globally are altering monsoon cycles, disturbing complex hydro-meteorological systems, which in turn “may worsen the water stress across the country, making the interlinking projects ineffective or possibly even counterproductive,” it says.
The logic behind inter-basin water transfers tracks with mathematical concepts of surplus and deficit: excess water is routed from “donor river basins” (for instance, from the Godavari river in Telangana) to “recipient” dry regions (Grand Anicut dam on Cauvery); if a maximum of water is kept on land, and does not flow into the Arabian Sea or Bay of Bengal, India’s growing water demand could be met. The presupposition is that river basins operate in silos without affecting the land or the atmosphere, but “here, we find that the assumptions made for the interlinking are not valid,” the study stated.
