India’s river connectivity can transport invasive species to multiple areas
The National River-Linking Project is the most ambitious project of its kind in the world to date, proposing to link 37 major river basins across India through 30 links, potentially reallocating approximately 174 billion cubic meters of water from “surplus” to “deficit” basins while simultaneously generating approximately 34,000 MW of power.
However, the project has also raised serious concerns about its environmental costs. Experts said the idea of ”surplus” and “deficit” basins can mask seasonal and interannual fluctuations in river flows, and that transferring water between basins can alter downstream flows, sediment transport, floodplains, deltas and the habitats that depend on them. Dams, reservoirs and canals can also break ecosystems apart, disrupting fish migration and other ecological processes.
Climate change also complicates assumptions about how much water the basin will reliably have available for transfer in the coming decades. However, linking rivers also seems to pose another, less obvious problem.
“Ecological highways”
Recently, researchers from the Ashoka Trust for Research in Ecology and the Environment (ATREE), Bengaluru, assessed that the project may also create “ecological highways” along which invasive species can travel to new, ecologically sensitive areas.
Their findings were recently published in Scientific Reports.
Because of how India’s watersheds are isolated from each other, many of the species in each are endemic, meaning they inhabit a small area and are found nowhere else on the planet. River connectivity can then threaten them more than native species.
“There is no public or verifiable scientific basis to support any claim about the benefits of the National River-Linking Project, but rather an imaginary basis that when you connect a drier part to a wetter part of the country, it creates a water balance, contrary to how ecology actually works,” said Siddharth Agarwal, director and founder of the non-profit Veditum India Foundation.
In the paper, the team showed that all northeastern and peninsular Indian basins are more vulnerable to biological invasions than those in central and northern India.
The Southwestern Ghats, Kaveri, Krishna Lower Ganges and Brahmaputra basins support diverse habitats and complex ecological niches that host native species, endangered species and invasive alien species.
“Invasion Hotspots”
“Right now, (invasive alien species) are isolated, confined to individual watersheds,” said study lead author and ATREE senior fellow Aravind Neelavar Ananthram. “By connecting rivers, we would not only introduce new species that do not occur naturally, but also increase the vulnerability of native species that cannot compete with invasive alien species.”
The finding is consistent with global research suggesting that biodiversity hotspots may be accumulating more invasive alien species, threatening the long-term prospects of native species and becoming “invasion hot spots” themselves.
For example, the Lower Ganges basin hosts 13–15 invasive alien species and could become a major source of invasive species for the Mahanadi, which is home to 69 threatened species. In fact, this is one of the project’s most ecologically sensitive links and could increase the risk of endangered species becoming extinct.
The water connection within the Project could also help the spread of aquatic pathogens, disrupt the migration routes of fish and flatten the unique biota that individual basins are proud of today.
“Fish in one watershed may be well adapted or immune to the pathogens it harbors, while species in other watersheds may not be able to defend themselves against such pathogens,” said Dr. Ananthram. “If water flow is reduced by taking water from one river and transferring it to another, downstream water flow will be reduced. As a result, downstream biodiversity will be severely affected, and there is a high probability that downstream endemic species may become extinct.”
“The river interlinking project is being marketed as a solution (at least for the Ken-Betwa) to water scarcity (in Bundelkhand), but can it really serve the purposes it proposes?” asked Mr. Agarwal. “There’s no way to verify that. It’s more of a capital investment than an environmental one.”
The need for foresight
“Rivers like the Ken have sand of great ecological value. But when the Ken-Betwa confluence is alive, a lot of water is moved away from the river, reducing the volume of flow and reducing the rate of sediment production in the river,” Mr Agarwal said. “This could ultimately reduce biodiversity in the river and potentially even trigger a collapse of the food chain.”
The effects of the project may also extend to downstream countries.
“Right now we only considered 15 freshwater invasive species for which data are available,” said Dr. Ananthram. “If we look at all the species in India, including terrestrial and marine systems, there would be around 350 to 400 species in various stages of invasion. Developed economies like Australia and Europe have very strong policies on invasive alien species. There is an urgent need for India to come up with a specific policy to regulate, manage and control” such species.
Incorporating evidence-based watershed management into national infrastructure planning could provide ecological forecasting.
“The health risks, biodiversity, wildlife and economic costs (of the Project) to India, especially to the agro-economy, farmers’ livelihoods and fisheries, are matters of urgent attention,” he added. “While the government’s intention may be good in addressing the water deficit, development plans and policy decisions should be holistic and address the ecological impact, impact on biodiversity and people’s lives.”
Jhinook Mitra is an independent researcher and environmentalist, currently working at the Bengaluru Wildlife Foundation.
Published – 30 Sep 2026 09:15 IST