River interlinking projects could alter India’s monsoon, study warns

A recent study published in the journal Nature Communications has raised concerns about the potential impacts of proposed river interlinking projects on the monsoon in India. The research, conducted by the Indian Institute of Technology, Bombay (IIT-B), the Indian Institute of Tropical Meteorology (IITM), Pune, and universities in Australia and Saudi Arabia, used climate modeling to investigate these impacts.

Inter-basin Transfer Alters Monsoon Patterns

The researchers found that inter-basin transfer of water from major rivers such as the Ganges, Brahmaputra, Mahanadi, and Godavari could lead to reduced soil moisture in north-central India. This moisture deficit could affect the coupling between land and atmosphere during the monsoon, leading to changes in monsoon rainfall patterns.

Rainfall may decrease in North and Central India, while it may increase in South India. This shift will affect the spatial distribution of the monsoon. The researchers suggest that a detailed study of the potential climate impacts of these projects is necessary before interfering with the natural flow of rivers on such a large scale.

The government has proposed river interlinking projects to transfer water from basins with relatively more water to basins with less water to meet the increasing water demand of the population. However, this research has revealed that these projects could disrupt the interaction between land and atmosphere, affecting the amount of moisture in the air and wind patterns, and leading to changes in rainfall patterns across the country.

Rainfall may Reduced by 12%

Subimal Ghosh, a researcher from the Department of Civil Engineering at IIT-B, says, “Taking water management decisions that consider the whole systems approach of the water cycle will yield maximum benefits for large-scale hydrological projects like river interlinking.” Roxy Mathew Cole from IITM adds, “We must thoroughly assess any river interlinking project before undertaking it.”

According to this study published in 'Nature Communications a few days ago, due to this, there could be a possible decrease of up to 12% in the average rainfall during September in some dry areas of India. These are the areas that are already facing water shortages.

Assessment vital for river Interlinking

Roxy Mathew Cole from the Center for Climate Change Research, IITM, says, “Analysis of long-term data shows that there has been a change in monsoon rainfall patterns in some river basins – specifically a reduction in the total amount of monsoon rainfall and There has been a trend towards longer dry periods. Therefore, it is extremely important that any river interlinking project is thoroughly assessed before undertaking it."

He adds, "Also, due to reduction in rainfall, post-monsoon, one water-bearing basin may become vulnerable to other water-deficient basins. The capacity to send water may also reduce. Therefore, we recommend understanding the impacts of land-atmosphere feedback and re-evaluating decisions before making river interlinking decisions, as the critical importance of water balances in interconnected river basins."

Australian Research Council Center of Excellence for Climate Extreme, Anjana Devanand of the University of New South Wales, Sydney, says that like river basins around the world, Indian river basins were under severe stress due to global and climate change.

"The Indian summer monsoon from June to September brought water to river basins. It is the primary source of rainfall, which accounts for about 80% of the country's annual rainfall and controls the GDP. Over the past few decades, the Indian summer monsoon has experienced a decline in average rainfall. The intensity, incidence and spatial variability of rainfall have increased. “Such changing meteorological patterns have increased hydrological extremes, floods and droughts.”

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