So what? Ganga is Ganga - Research by Delhi geologists points to longer river that has been overlooked

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By G.S. MUDUR
  • Published 26.12.14
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New Delhi, Dec. 25: The Ganga may lose its status as the longest river in the nation’s largest river basin. New research by a team of Indian geologists has suggested that an even longer river in the basin has long been overlooked.

The world’s river basins are typically named after what hydrologists call the master stream, usually the longest river, flowing through the basin. Until now, hydrologists have assumed that the Ganga was the longest river in the basin.

However, the geologists have underscored that their study was a “purely scientific exercise” and it had nothing to do with the names of rivers or the basin.

The scientists at the University of Delhi have found that the Ganga, whose length is estimated to be about 2,600km, is not the longest river in the basin.

A river, defined by segments that begin at the source of the Tons river in the Banderpunch mountains in Uttarakhand, is instead the longest in the basin.

This river, which merges with the Yamuna in Kalsi and then with the Ganga in Allahabad, has a length of about 2,758km from the source of the Tons to the confluence with the Brahmaputra.

The results of the study appeared today in the journal Current Science, published by the Indian Academy of Sciences. The scientists used a mix of geological and topographic data to measure segments of major rivers and tributaries across the basin.

“This is a purely scientific exercise, we’ve tried to determine the longest river in the Ganga basin, this exercise has nothing to do with names of rivers or the basin,” said Vimal Singh, an assistant professor of geology at the University of Delhi, who led the study.

The study by Singh and research scholars Neelam Verma and Rahul Devrani also implies that appropriate acknowledgement of the length of the Tons-Yamuna-Ganga segments will elevate the global ranking of the longest river in the Ganga basin from 34th to 31st in the world.

“The longest river is considered the master stream in a river basin,” said Sampat Kumar Tandon, professor of earth sciences at the Indian Institute of Technology, Kanpur, who was not associated with the study. “The Tons-Yamuna-Ganga emerges as the master stream in the Ganga river basin.”

The Ganga branches into the Hooghly and the Padma downstream of the Farakka Barrage, with the Padma flowing into Bangladesh where it merges with the Brahmaputra before draining into the Bay of Bengal.

The University of Delhi geologists have proposed that the Tons-Yamuna-Ganga river be named, for “scientific studies”, the Himalayan Foreland River and be recognised as the axial or trunk river of the Ganga river basin. The length of this river increases to about 3,000km when the length of the Hooghly, its minor distributary, is taken into account.

But a scientist who specialises in river dynamics said the identification of a longer river by looking at multiple source points and joining river segments within a basin doesn’t change anything.

“So what?” asked Rajiv Sinha, professor of earth sciences at IIT Kanpur. “The role of a river in a basin doesn’t come from length alone — the flow of the Ganga is along the axis of the valley, that’s what defines the central river in a basin.”

“And when a tributary merges into a river, the tributary ceases to exist,” Sinha said.

Singh and his co-workers have pointed out that the water discharge and depth of the Yamuna are greater than that of the Ganga at Allahabad where the rivers merge. But Sinha contends there is less water in the Ganga because huge amounts are extracted through a network of canals upstream.

The Delhi geologists have said their findings will have implications for studies and projects on the Ganga river. “It would be important to consider what the Tons and the Yamuna discharge into the Ganga,” Singh said.

The Narendra Modi government had earlier this year launched the Integrated Ganga Conservation Mission called “Namami Gange”, earmarking Rs 2,037 crore for the initiative that would be used in efforts to clean the river through appropriate management of sewage and industrial discharge.

In September this year, Modi had chaired the first meeting of the Namami Gange mission and called for a plan to rejuvenate the river. The Centre has also allocated Rs 100 crore for initiatives to beautify riverfronts in Kedarnath, Haridwar, Kanpur, Varanasi, Allahabad, Patna, and Delhi.

India’s efforts to clean up the Ganga have used up over Rs 3,000 crore since 1986, but environmental scientists say long stretches of the river continue to be embarrassingly polluted.

The scientists say the resources invested in clean-up action have not kept pace with population growth, urbanisation and the burgeoning flow of sewage and effluents into the river. About 70 per cent of the pollution in the river is domestic sewage.