River interlinking projects in India raise concerns about water stress, study finds

India’s ambitious river interlinking projects, which aim to tackle the country’s growing issues of droughts and floods, may unintentionally exacerbate water stress and disrupt monsoon patterns, warns a study published in the journal Nature.

The study employed various techniques, such as regional climate models and reanalysis data, to provide insights into the complex network of hydro-meteorological consequences that could be triggered by these extensive infrastructure ventures.

The researchers, including those from Indian Institute of Technology (IIT) Bombay and Indian Institute of Tropical Meteorology (IITM), Pune, conducted a study focusing on the summer monsoon season in India. This season is crucial for the country’s water cycle and agriculture.

The study aimed to understand the complex relationships between different river basins by incorporating atmospheric variables, including the El Niño-Southern Oscillation (ENSO). The researchers discovered intricate causal pathways between the basins, driven by feedback loops between the land and the atmosphere.

These feedback loops create connections between various land variables, such as soil moisture, and influence the moisture content of the air, temperature, and precipitation in different basins.

The study identified certain river basins as “donor basins” with more outgoing links, meaning they contribute moisture to other basins. On the other hand, some basins were labeled as “recipient basins” with a higher number of incoming links, indicating that they receive moisture from other basins.

The study found that there are both positive and negative interactions between river basins when it comes to the exchange of land and atmosphere. For example, the moisture levels in one basin could either decrease or increase the moisture levels in another basin, depending on the specific feedback mechanism involved.

According to the research, the implementation of river interlinking projects, which involve the transfer of water between different basins, could disrupt the interactions between land and atmosphere. This disruption could have an impact on the moisture content of the air and the patterns of wind. These changes, in turn, could result in alterations to the rainfall patterns observed throughout the country.

“The findings of this study carry significant implications for India’s massive river interlinking projects,” the authors of the study wrote in their paper.

“The proposed projects involve transferring water from surplus to deficit river basins through reservoirs and canals without a comprehensive understanding of the hydro-meteorological consequences,” they said.

The researchers have pointed out that one of the significant concerns highlighted by their research is the potential decrease in mean rainfall during September by as much as 12 percent in regions of India that are already experiencing water stress. This decrease in rainfall is attributed to the increased irrigation resulting from transferred water. The researchers have further stated that this situation may worsen the water stress across the country, making the interlinking projects ineffective or possibly even counterproductive.

The researchers, in collaboration with the University of Hyderabad and King Abdullah University of Science and Technology, have made an intriguing discovery. They found that during La Niña years, which are characterised by cooler sea surface temperatures in the tropical Pacific Ocean, the impact of drying becomes more severe compared to El Niño years. This intensifies the challenges faced by interlinking projects.

Based on these significant findings, the researchers emphasize the essentiality of conducting model-guided impact assessment studies for large-scale hydrological projects, not only in India but worldwide. These assessments should take into account the intricate interactions and feedbacks between land and atmosphere, which can directly influence water availability and climate patterns.This study highlights the utmost importance of gaining a comprehensive understanding of complex hydro-meteorological systems when planning and implementing infrastructure projects that impact water resources. It urges policymakers and stakeholders to carefully consider the potential consequences of river interlinking on the nation’s water security and climate resilience.

By considering these findings and taking a holistic approach, policymakers can make more informed decisions regarding water resource management and safeguarding the environment.