A research team led by scientists and researchers of IIT-Bombay and the Physical Research Laboratory, Ahmedabad has stated that they have found ample evidence of a perennial river on the plains of Northwestern India, that had led to the flourishing of early Harappan civilisations in the area.
As per a report in the Times Of India, contradicting the earlier beliefs that the Harappan civilisation depended upon monsoon, ample evidence has been found that suggests that a considerable number of Harappan settlements had flourished along the ancient course of a modern seasonal stream called Ghaggar in Northwestern India.
The new research by the Physical Research Laboratory, Ahmedabad, in collaboration with IIT-Bombay has stated that there is enough evidence to say that there was a perennial river in the parts of Northwestern India that followed along the current course of Ghaggar. The scientists believe that it is the ancient river Saraswati mentioned in the Rig Veda.
The research work has been published in the recent issue of the scientific journal ‘Nature’ under Scientific Reports and is available in the public domain.
The research says that the Saraswati was perennial and had flowed from the higher Himalayas between 7000 and 2500 BC. The Harappans had built their earliest settlements along the perennial Saraswati between 3000 and 1900 BC. The decline of Saraswati eventually led to the collapse of Harappan civilisation, the research adds.
It also says that the demise of the river and the Harappan civilisation approximately coincide with the onset of the Meghalayan stage, the current dry state of global climate that began 4200 years ago.
The scientists involved in the study also say that while the Saraswati had sources in the glacial regions of Himalaya, similar to the Ganga, Yamuna and Sutlej, the current Ghaggar has no direct connection to the higher Himalayas and originates from the Siwalik, the foothills of Himalaya.
Scientist JS Ray from the Physical Research Laboratory says that the only likely path for the glacier melt was the ancient course of the modern-day Ghaggar could have been through the distributaries of the Sutlej river.
The scientists have determined the depositional ages of the coarse-grained white sand layers that occur 3-10 meters below the modern alluvium of the Ghaggar’s flood plains.
The dating of the layer was done with the radiocarbon and optically stimulated luminescence methods at the PRL. Scientist JS Ray explains they found that the perennial river had uninterrupted flow starting 80,000 years ago and continued till 20,000 years ago. It then started diminishing due to the extreme aridity of the later glacial period. However, the river gained strength some 9000 years ago and continued till 4500 years ago.
The decline of Saraswati’s flow is said to have started due to the drying up of the Sutlej-fed channels. The later epics such as the Mahabharata also describe the Saraswati’s diminishing flow, till it all but disappeared.
The scientists associated with the study are Anirban Chatterjee, J S Ray, and Anil Shukla of PRL, along with Kanchan Pande of IIT Bombay.