The climate blind spot in India’s river interlinking projects

Subject : Geography

Section: Physical geography

Context:

The river interlinking project is a $168 billion project to transfer excess water from one river basin to the other. It is seen as a permanent solution to the drought situation.
A new study published in Nature Communications, however, challenges these claims.

Details of the study:

Logic behind inter-basin water transfers: excess water is routed from “donor river basins” to “recipient” dry regions; 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.
Impact of interlinking projects includes:
- Surplus irrigation due to interlinking basins modifies the spatial patterns of summer monsoons, and was responsible for a 12% decrease in mean rainfall in September across dry arid regions that were already experiencing water stress.
- The river basins do not act as independent entities; they are connected to one another through feedback loops between the land and atmosphere, links that are formed when water evaporates from one basin or when winds transport water across basins.
- It can alter the moisture content of the air and patterns of wind. They impact summer monsoons and create a feedback loop, impacting water availability and climate patterns.
- Excess irrigation (using transferred water) caused soil moisture to dry up, which corresponded with a decline in rainfall and increased temperatures across the entire central Indian belt, more visible during the La Niña years.
A 2017 paper warned that moving even slightly away from the natural flow regime (the recorded historical pattern of floods and droughts) can lead to a collapse in the structure of ecological networks.

Interlinking of basins:

The Indian Rivers Inter-link is a proposed large-scale civil engineering project that aims to effectively manage water resources in India by linking Indian rivers by a network of reservoirs and canals to enhance irrigation and groundwater recharge, reduce persistent floods in some parts and water shortages in other parts of India.
The National Perspective Plan (NPP) for inter-basin transfer has identified 16 links under the peninsular rivers component and 14 links under the Himalayan component, charged with transporting 174 billion cubic metres of water each year using some 15,000 km of canals and 3,000 reservoirs.
As per the Plan, these could increase the irrigated areas across the country by 30 million hectares; benefits would also pour in the form of 34,000 MW of hydropower generation, employment generation, salinity control, and pollution abatement, among other aspects.

Water availability in India:

India accounts for 18% of the world population and about 4% of the world’s water resources.
The current per capita availability of water in India is around 1400 cubic meters, slated to reduce to about 1200 cubic meters by 2050, according to the Central Water Commission.
The mean rainfall from the summer monsoon, which accounts for almost 80% of the annual showers, has steadily declined, while erratic rainfalls have dominated, worsening India’s floods, droughts and water stress.

Source: TH