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The discovery of a 200 kilometre-long underground palaeo-channel stretching from Prayagraj to Kanpur in Uttar Pradesh has reignited debate around one of India’s oldest and most enduring beliefs — the existence of the mythical Saraswati river.
For centuries, Hindu tradition has held that the Saraswati meets the Ganga and Yamuna at the Triveni Sangam in Prayagraj, despite the river itself remaining invisible. Now, scientists say they have identified the buried course of an ancient river beneath the Ganga-Yamuna Doab, lending fresh attention to the legend.
Researchers have found a massive palaeo-river channel — the remnant of an extinct river system — buried 10 to 15 metres below the surface along a nearly 200 km stretch between Prayagraj and Kanpur. The discovery has triggered renewed scientific interest in the geological history of the region and its possible links to ancient river systems described in historical texts.
Scientists say this is not a simple geological structure, but may be evidence of an independent ancient river system separate from the Ganga and Yamuna.
The discovery was made by scientists at the Council of Scientific and Industrial Research-National Geophysical Research Institute, Hyderabad, using advanced heliborne transient electromagnetic technology, or H-TEM, and confirmatory drilling to examine the ground.
Subhash Chandra, a senior scientist involved in the project, recently told the media and posted on social media that the physical presence of this river, flowing between the Ganga and Yamuna rivers from the confluence at Prayagraj to Kanpur, had now been fully established.
According to him, dedicated drilling has confirmed this, leaving no doubt.
According to scientists, the underground river channel is four to five kilometres wide, making it comparable to major rivers such as the Ganga and Yamuna.
Most importantly, its depth and base level are similar to those of the Ganga and Yamuna. This is why scientists consider it a separate third river system, rather than an old stream or abandoned river channel.
Chandra said in a media interview that if a river had simply changed course, its geological level would be different. But in this case, the base levels of all three appear to be almost the same.
This suggests that it may have been a completely independent river.
The discovery began in 2012, when heliborne transient electromagnetic technology was used for groundwater exploration for the first time in India.
The following year, pilot surveys — preliminary test surveys — were conducted in six different geological regions.
The initial survey, conducted between Prayagraj and Kaushambi, revealed indications of an underground channel approximately 45 km long.
Based on subsequent detailed surveys and drilling, the study was published in Geophysical Research Letters, a research journal of the American Geophysical Union, in December 2021.
The paper states that airborne electromagnetic probe findings, drilling and logging data — records of layers within the ground — clearly establish the presence of this massive palaeo-channel and its groundwater network.
The National Mission for Clean Ganga subsequently expanded the project.
A tripartite agreement between the National Mission for Clean Ganga, the Central Ground Water Board and the CSIR-National Geophysical Research Institute led to a detailed survey from Kaushambi to Kanpur.
More than 5,000 linear kilometres of heliborne data were collected, and a technical report was submitted in 2022.
During this phase, the total mapped length of the underground river reached approximately 200km.
Scientists believe the discovery is important not only from a historical and cultural perspective, but also in the context of the water crisis.
Amid rapidly declining groundwater levels in the Gangetic plains, this underground channel could serve as a massive natural aquifer — a porous layer that stores water underground.
According to the report, six sites have been identified between Prayagraj and Kanpur where this underground river can be recharged. This would not only replenish the underground river, but also the drying aquifers of the Ganga and Yamuna.
Research has also found that the palaeo-channel is filled with highly porous and permeable geological structures.
This means that its clay and sand layers allow water to pass through easily and accumulate within it.
Its winding structure resembles an active river system. Scientists consider it extremely useful for future managed aquifer recharge, or artificial groundwater recharge — the planned infusion of rainwater or surface water into the ground.
However, the survey had limitations.
Heliborne surveys could not be conducted over the city of Prayagraj because dense population, power lines and construction activities obstruct electromagnetic sensors.
At present, the channel can be clearly traced only up to about 25km before the confluence.
Scientists say this does not mean the river does not reach the confluence.
The CSIR-National Geophysical Research Institute is now developing electrical-field vector resistivity imaging, or EVRI, technology, which will be able to image deep underground even in urban areas.
The discovery has also given a new direction to the long-standing debate about the existence of the Saraswati river.
Scientists are currently hesitant to directly identify the underground channel as the Saraswati, saying further investigation of historical and geological evidence is necessary.
However, the fact that this river channel has been found in the same geographical area where the Saraswati’s flow is mentioned in Vedic literature is considered significant.
The next challenge for scientists is to determine how far westward the underground river extends.
Preliminary research suggests its origin may be linked to a Himalayan river system.
