The source and fate of the mythological Saraswati river has generated plenty of debates worldwide. While a majority of Indian authors including leading geologists hold the view that the origin of river Saraswati was Himalayas, there are some who differ.
US geologist Liviu Giosan of Woods Hole Oceonographic Institution (WHOI) offers a contrary view in a study titled 'Fluvial Landscapes of the Harappan Civilization'.
The study, which was published in the Proceedings of the National Academy of Sciences of the USA in 2012, says: "Contrary to earlier assumptions that a large glacier-fed Himalayan river, identified by some with mythical Sarasvati watered the Harappan heartland on the interfluve (land between two rivers) between the Indus and Ganges basins, we show that only monsoonal-fed rivers were active there during the Holocene (the geological era since the end of ice age about 11,000 years ago).
As the monsoon weakened, monsoonal rivers gradually dried or became seasonal, affecting habitability along their courses. Hydroclimatic stress increased the vulnerability of agricultural production supporting Harappan urbanism, leading to settlement downsizing, diversification of crops, and a drastic increase in settlements in the moister monsoon regions of the upper Punjab, Haryana and Uttar Pradesh."
A WHOI document, interpreting Giosan's study, said that based on scriptural description, it was believed that Saraswati was fed by perennial glaciers in Himalayas. Today, an intermittent river that flows only during strong monsoons and dissipates into the desert along the dried course of Hakra valley is thought to best approximate the location of mythic Saraswati but its Himalayan origin and whether it was active during Vedic times remain controversial.
Giosan's study was challenged by Indian geologist KS Valdiya in his article 'River Saraswati was a Himalayan born river'.
"I have put forth a number of evidence gathered in the last 10-15 years to show that Giosan's arguments were not acceptable. Changes which took place and are taking place on earth's surface are not all due to the increase-decrease of rainfall due to climate change. Rainfall is not the only decisive factor. There are equally powerful factors such as tectonic activities. The Saraswati domain experienced recurrent neo-tectonic activities, often very powerful,'' wrote Valdiya.
Valdiya said that not only Saraswati basin but also the Indus plains experienced tectonic (pertaining to structure of earth's crust) resurgences many a times.
"A period of increased flooding and sediment deposition followed by avulsion (abandonment of river channel) away from the city is a reasonable explanation for its abandonment. This is exactly what I have been pleading all along in Saraswati's case. Harappan people migrated en mass earlier to north, northeast and later to south and southwest when Saraswati water diminished and were forced to leave homes when it dried up due to tectonically-induced river piracy.