My Article on River Sarasvati (‘In Search of a river’, NSE,December 21, 2003) brought an avalanche of mail from readerswanting to know what happened to the river. Why and how did itdisappear?Rivers change course frequently, even disappear. The Palar in TamilNadu was once a mighty river that flowed from Nandidurg in Kolartill it entered the Bay of Bengal at Mamallapuram. The 20th centurysaw the death of the Palar, where sewage is the only liquid in theriver bed. Even perennial rivers change their course: The Gangaonce flowed through ancient Pataliputra, but has moved away frommodern Patna.A fault-line runs along the Aravalli range in a north-northeastdirection, even through Delhi. Coupled with this fault-line is theinter-plate tectonics, moving in the same direction, caused by theclash of the Deccan Plateau (or Indian plate) with the Eurasianplate. The plate runs along and parallel to the course of theSarasvati and the Indus, until it reaches the Himalayas. Platetectonics is responsible for the continuing rise of the Himalayasand the formation of new glaciers that are the source of the northIndian rivers. The combination of the fault line and platetectonics has made Northern and Western India into a veryearthquake-prone zone.An earthquake coupled with rising sea and land levels destroyedDwaraka. People living in North India are used to frequent tremors,and those living in the hills to frequent earthquakes. Thedevastating earthquakes that hit Latur in Maharashtra and Kutchindicate the damage that plate tectonics continue to cause. Amassive tectonic upheaval around 1663 BC caused the easternSiwaliks to move north, forcing the west-flowing Sarasvatisouthwards. The river lay directly on the fault line, whichcontinues to be active. The shifting plates were also responsiblefor the rise of the Siwaliks, and the land mass of Rajasthan andSindh.Tectonic activity changed the course of the Sarasvati; the Sutlej,which once flowed into the Sarasvati, and the Indus shiftedwestwards; the Yamuna dug deeper and captured the flow of theSarasvati's waters to the Ganga via the Chambal River. Thus theGanga, Yamuna and Sarasvati did flow together towards Prayag, theGanga taking away the discharge of the Sarasvati even as the Yamunamoved eastwards. The Red Fort, once built on the Yamuna's banks, isnow several kilometres away, and the river has shifted 10-40kilometres east of Krishna's birthplace on the river's right bankin Mathura.The rise of the Aravalis caused the eastern shift of the Yamuna andthe abandonment of Indus-Sarasvati cities between 2000 and 1500 BC.It also created several lakes out of Sarasvati's waters, lakes thatlater became saline due to the intense aridity. The word saras alsocame to mean lake at a later date, probably because the rivershrank into several lakes before it finally disappeared.Reader S N Balasubrahmanyam of Bangalore suggests that there wasprobably an intermediate stage of water backing up into one largelake, and that rather than disappearing into the desert innortheast Rajasthan, Sarasvati may have dried up when the waters ofthe Sutlej and Yamuna rivers were diverted by tectonic activity.But geological evidence suggests that several saline lakes ofRajasthan were left by the river. Sarasvati did survive as asmaller Sarsuti that merged into the Ghaggar and then disappearedinto the Thar Desert. Tectonic changes, diversions and “preying” byother rivers all combined to dry up the Sarasvati. A combination ofcircumstances resulted in choking the river and inspiring theMahabharata to say that the Sarasvati “disappeared” intoMarusthali, the Thar Desert.But plate tectonics only tell a part of the story. TheIndus-Sarasvati civilisation was primarily urban, with 2600centres. Urban conglomerations are environmentally unsustainable,and the excellent drainage systems, bathrooms and water supply forwhich the Harappans are lauded would have polluted and halted theflow of the river. The cold winters, cooking requirements, and thebrick and pottery industry would have resulted in large-scaletree-felling for fuelwood, silting the river. The Harappansproduced vast quantities of baked clay products — bricks forhouses, wells and streets, pots, seals and artifacts. Pottery isnot biodegradable, although it is produced from the earth. Itbreaks easily, cannot be recycled or reused and remains forever, aspotsherds. To produce clay goods, large amounts of sand are removedfrom the river banks and beds, causing great environmental damage.All these must have contributed to the degradation of the river andits cities.Cities are parasites that drain the environment. They are supportedand fed by rural agriculture and create implements and technologiesto increase food production. As cities become greedier forresources, villages can no longer support their people, who flockto cities for survival, straining natural resources further. Citiesproduce great intellectual and technical developments, but theyalso prey on natural resources. In the third millennium BC, thecities of the Nile, Tigris-Euphrates and Sindhu-Sarasvati wereabandoned at various stages due to environmental degradation.Urbanisation is an unavoidable evil. Have you seen the Yamuna atDelhi? It is stagnant with garbage and sewage. If the river can nolonger flow on its present route, the flow will be diverted. Amassive earthquake and a change of land levels could cause theriver to dry up completely.An eminent scholar asked me how the highly urban and prosperousIndus-Sarasvati civilisation became rural. When cities collapse,they revert to rural life styles. Kanchipuram is one such examplein the historical period. It was once a “city of cities” —nagareshu kanchi — and a university town where Indian princes andinternational scholars came to study, a centre of weaving,metallurgy and vegetable oil production. In time, it becameunsustainable, primarily because the Palar River dried up. Today itis smaller than most towns of Tamil Nadu, and more rural,surrounded by paddy fields. The weavers have moved to surroundingvillages and sell their goods in the shops of Chennai, while themetal and oil production units have closed down.Balasubrahmanyam adds that a major shift in geographical featureshas taken place within historical times, but is never taken intoaccount in a discussion of civilisation in South Asia. How true!Sarasvati was the location of the Harappan and Vedic civilisations,and cities that disappeared between 2000 and 1500 BC, leavingbehind a great mystery. She was flowing in the period of the Rigand later Vedas and disappears during the Mahabharata. Balaramagoes on a pilgrimage down the Sarasvati from Mathura to Dwarka.Arjuna follows the disappearing river into the desert. This makesparts of the epic very ancient, but we have yet to study them. Thebest source of information on the river is K S Valdiya's Saraswati— The River That Disappeared brought out by ISRO and published bythe Universities Press (India) Limited.The Rig Veda describes cities and grazing, droughts and floods.Later literature describes villages and forests and fewer cities.Perhaps that is why the Indian seers and philosophers regarded theenvironment as sacred and treated every component with reverence.They knew the power of nature to destroy her own creations.