Indian satellites find water under desert
Hyderabad July 28. India's remote sensing satellites have traced the
buried course of Saraswati, the mythical Himalayan river, kindling
hopes of finding drinking water under the hot sands of the Thar
desert in Rajasthan.
Mentioned in the Rig Veda, the Hindu scripture, and other ancient
literature, the river is believed to have once flowed, parallel to
the Indus, through what is now desert before falling into the Arabian
Sea.
According to published literature, the river disappeared between 5000
BC and 3000 BC due to tectonic events in the Himalayas, that cut off
the water supply, and climatic changes that converted what was once a
lush green Rajasthan into an arid zone.
Past attempts to accurately trace the lost river and reconstruct its
drainage system did not succeed.
"Recent advancements in space-based sensors and in data processing
technologies made it possible", says J. R. Sharma of the Jodhpur-
based Remote Sensing Service Centre of the Indian Space Research
Organisation (ISRO).
He and his colleagues, A. K. Gupta and G. Sreenivasan have mapped
the "palaeo channels" relics of the river and its tributaries
using data from three different sensors on board Indian satellites.
Mr. Sharma said over telephone that 13 borewells drilled along the
predicted river course have yielded water at a depth of 35 to 40
metres.
The size of the palaeo channels, as estimated from satellite data,
was huge, about 15 to 40 metres thick, implying that there was plenty
of water out there. "The Government of Rajasthan is planning to
increase the number of borewells to 50 in two months and has
earmarked Rs. 40 million for the project," he said, adding, "chemical
analysis indicates these palaeo channels could form a source for good
quality ground water."
The ISRO scientists do not subscribe to the theory that Saraswati is
flowing as a subterranean river. "Radioactive tracer studies show
that the maximum flow of water is 15 cms per year too slow to
indicate that connection with the Himalayan source is still there,"
Mr. Sharma said.
PTI
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