Saturday, September 27, 2008

The Saraswati: Where lies the mystery

Climatic change and neotectonic movements have led to migration and abandonment of several rivers and drainage systems. Some of them are ‘lost’ because of the overburden of silt. But several evidences left by them usually help in proving the existence of a geomorphic feature in a particular location, which attract the attention of the interested people to discover the past. In India, the river Saraswati reflects such a fascinating history, supported by geological, hydrological and archaeological evidences as well as the records of the most modern tools, such as remote sensing and GIS. With the aid of remote sensing through orbiting satellites, the mystery of the river is more or less solved.

History behind the mystery

The satellite imagery of Saraswati river

Geological record indicates that during the late Pleistocene glaciation, the water of the Himalayas was frozen and that in the place of rivers, there were only glaciers, masses of solid ice. When the climate became warmer, the glaciers began to break up and the frozen water held by them surged forth in great floods, inundating the alluvial plains in front of the mountains. The melting of glaciers has also been referred in Rig Vedic literature, in mythological terms. It was the first interglacial period in Holocene marking the break-up of glaciers and release of the pent-up waters that flowed out in seven mighty river channels referred as the ‘Sapta Sindhu’ in the Rig Veda, traced from east to west. The ‘Sapta Sindhu’ refers to the rivers Saraswati, Satadru (Sutlej), Vipasa (Beas), Asikni (Chenab), Parosni (Ravi), Vitasta (Jhelum) and Sindhu (Indus). Among these, the Saraswati and the Sindhu were major rivers that flowed from the mountains right up to the sea. The hymns in praise of the Saraswati are probably some of the oldest, composed more than 8000 years ago.

For 2000 years, between 6000 and 4000 B.C., the Saraswati flowed as a great river. R. D. Oldham (1886) was the first geologist who argued logically pointing to the great changes in the drainage pattern of the rivers of Punjab and western Rajasthan converting a once fertile region into a desert. According to geological and glaciological studies, the Saraswati was supposed to have originated in Bandapunch massif (Saraswati-Rupin glacier confluence at Naitwar in western Garhwal).

The river, which had originated from Kapal tirith in the Himalayas in the west of Kailash, was flowing southward to Mansarovar and then taking a turn towards west. Even today the Saraswati flows from the south of Mana pass which meets river Alaknanda, 3 km away in the south of Mana village. Descending through Adibadri, Bhavanipur and Balchapur in the foothills to the plains, the river took roughly a southwesterly course, passing through the plains of Punjab, Haryana, Rajasthan, Gujarat and finally it is believed to have debounched into the ancient Arabian Sea at the Great Rann of Kutch. In this long journey, the Saraswati is believed to have had three tributaries, Shatadru (Sutlej) originating from Mount Kailas, Drishadvati from Siwalik Hills and the old Yamuna. They flowed together along a channel, presently known as the Ghaggar River, which is known as Hakra River in Rajasthan and Nara in Sindh. Some experts consider these two rivers as a single river whereas others consider the upper course of the Saraswati as Ghaggar and the lower course as the Hakra River, while some others call the Saraswati of the weak and declining stage as the Ghaggar.

Ancient courses of Saraswati river in Bahawalpur province (Cholistan desert)

he river was obliterated within a short span, in the Quarternary period of the Cenozoic era, through a combination of destructive catastrophic events. The decline of the river appears to have commenced between 5000 and 3000 B.C., probably precipitated by a major tectonic event in the Siwalik Hills of Sirmur region. Geological studies reveal that the massive landslides and avalanches were caused by destabilising tectonic events which occurred around the beginning of Pleistocene, about 1.7 million years ago in the entire Siwalik domain, extending from Potwar in Pakistan to Assam in India. Those disturbances, linked to uplift of the Himalayas, continued intermittently. Presumably, one of these events must have severed the glacier connection and cut off the supply of melt water from the glacier to this river; as a result, the Saraswati became non-perennial and dependent on monsoon rains. The diversion of the river water through separation of its tributaries led to the conversion of the river as disconnected lakes and pools; ultimately it was reduced to a dry channel bed. Therefore, the river Saraswati has not disappeared but only dried up in some stretches.

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