The Other Aspect of River Teesta
River Teesta, along with its many tributary streams, is a life line of Darjeeling-Sikkim Hills and downstream plain areas. However, Teesta river system also displays its other aspect with horrific characteristics during monsoon season every year causing severe human-monetary-environmental miseries in the region and lowlands lying downstream. During this period the river becomes a major source of human insecurity.
River Teesta originates from the glaciers of north Sikkim at about 21000 ft. above mean sea level. It flows for about 107 miles in the mountainous region of Sikkim and Darjeeling Himalaya before it emerges at Sevok Railway Bridge into the alluvial plains of Bengal. The river traverses another 60 miles on North-Bengal plains and enters into Bangladesh. Thereafter it flows for a length of about 83 miles in Bangladesh before joining the mighty Brahmaputra at Chilmari in North West Bangladesh. While Teesta itself is a tributary river of mighty Brahmaputra the principal tributaries of Teesta include rivers like the great Rangit, Lish, Gish, Cheel, Neora, Relli etc. Almost all of them flow through Darjeeling and Sikkim Hills. The flows of Teesta River vary widely between different seasons. While the peak flood flow during the monsoon months (June-September) rise up to 0.5 million cusecs, the dry season flow dwindles to a mere 5,000 cusec during the dry season (in the month of February).
An Explosive River
River Teesta has with it valleys extremely prone to cloudbursts, landslides and flash foods. Further, deep and dense gullies and associated streams; rapid toe erosion; loose, jointed and fractured rocks and high intensity of rainfall in Teesta Basin have compelled experts to believe that probably Teesta is the wildest river in the whole of Himalayan Region. The landscape of the valley is being continuously reworked by natural forces and majority of the present slopes have been formed by earlier landslides. Scientists say that the explosive character of the Teesta Valley can be attributed to intense rainstorms in the region. River Teesta floods its basin and the associated downstream area badly every year during the monsoon causing unprecedented human-environment-monetary misery.
Of all the Himalayan Rivers, Teesta has the highest sediment yield. It, approximately, brings down 98 cum of silt per hectare of its catchment per year giving an annual denudation rate of 9.8 mm per year. And surprisingly, this is among the highest denudation rates estimated for any river valley in the world. Scientists have estimated the average denudation rate for the Darjeeling Himalaya alone in the order of 0.5 mm to 5 mm during a normal year. But during a year of catastrophic floods such as 1968, the denudation rate for that year can possibly go up to 20 mm. It is important to learn that monsoon rainfall is greater in Eastern Indian Himalaya than in its western counter part. Within eastern Himalaya again the rainfall is intense in Sikkim and Darjeeling Himalaya. The reason being: with the Rajmahal hills situated to the west and the Shillong plateau to the east there is no mountain range to protect the Teesta Valley from the sweeping monsoon winds rising from the Bay of Bengal. As a result the summer monsoon directly hits the foothills and the lesser Himalayan ranges of Darjeeling and Sikkim and gives the Teesta Valley exceedingly high burst of rainfall ranging between 3000 mm to 6000 mm every year.
According to Hunter’s Statistical Account of Bengal, Teesta was originally a river of Ganga basin. The Teesta River which at present times flows down from the Darjeeling and Sikkim hills into Bangladesh to meet up with the Brahmaputra used to flow into the Mahananda and the Ganga in Bihar about 220 years ago. In 1787, due to heavy flood and devastating earthquake Teesta shifted its course to Brahmaputra basin. If such sudden river capture occurs today, it will sweep away thousands of villages in a gigantic flash flood.
River Teesta, along with its many tributary streams, is a life line of Darjeeling-Sikkim Hills and downstream plain areas. However, Teesta river system also displays its other aspect with horrific characteristics during monsoon season every year causing severe human-monetary-environmental miseries in the region and lowlands lying downstream. During this period the river becomes a major source of human insecurity.
River Teesta originates from the glaciers of north Sikkim at about 21000 ft. above mean sea level. It flows for about 107 miles in the mountainous region of Sikkim and Darjeeling Himalaya before it emerges at Sevok Railway Bridge into the alluvial plains of Bengal. The river traverses another 60 miles on North-Bengal plains and enters into Bangladesh. Thereafter it flows for a length of about 83 miles in Bangladesh before joining the mighty Brahmaputra at Chilmari in North West Bangladesh. While Teesta itself is a tributary river of mighty Brahmaputra the principal tributaries of Teesta include rivers like the great Rangit, Lish, Gish, Cheel, Neora, Relli etc. Almost all of them flow through Darjeeling and Sikkim Hills. The flows of Teesta River vary widely between different seasons. While the peak flood flow during the monsoon months (June-September) rise up to 0.5 million cusecs, the dry season flow dwindles to a mere 5,000 cusec during the dry season (in the month of February).
An Explosive River
River Teesta has with it valleys extremely prone to cloudbursts, landslides and flash foods. Further, deep and dense gullies and associated streams; rapid toe erosion; loose, jointed and fractured rocks and high intensity of rainfall in Teesta Basin have compelled experts to believe that probably Teesta is the wildest river in the whole of Himalayan Region. The landscape of the valley is being continuously reworked by natural forces and majority of the present slopes have been formed by earlier landslides. Scientists say that the explosive character of the Teesta Valley can be attributed to intense rainstorms in the region. River Teesta floods its basin and the associated downstream area badly every year during the monsoon causing unprecedented human-environment-monetary misery.
Of all the Himalayan Rivers, Teesta has the highest sediment yield. It, approximately, brings down 98 cum of silt per hectare of its catchment per year giving an annual denudation rate of 9.8 mm per year. And surprisingly, this is among the highest denudation rates estimated for any river valley in the world. Scientists have estimated the average denudation rate for the Darjeeling Himalaya alone in the order of 0.5 mm to 5 mm during a normal year. But during a year of catastrophic floods such as 1968, the denudation rate for that year can possibly go up to 20 mm. It is important to learn that monsoon rainfall is greater in Eastern Indian Himalaya than in its western counter part. Within eastern Himalaya again the rainfall is intense in Sikkim and Darjeeling Himalaya. The reason being: with the Rajmahal hills situated to the west and the Shillong plateau to the east there is no mountain range to protect the Teesta Valley from the sweeping monsoon winds rising from the Bay of Bengal. As a result the summer monsoon directly hits the foothills and the lesser Himalayan ranges of Darjeeling and Sikkim and gives the Teesta Valley exceedingly high burst of rainfall ranging between 3000 mm to 6000 mm every year.
According to Hunter’s Statistical Account of Bengal, Teesta was originally a river of Ganga basin. The Teesta River which at present times flows down from the Darjeeling and Sikkim hills into Bangladesh to meet up with the Brahmaputra used to flow into the Mahananda and the Ganga in Bihar about 220 years ago. In 1787, due to heavy flood and devastating earthquake Teesta shifted its course to Brahmaputra basin. If such sudden river capture occurs today, it will sweep away thousands of villages in a gigantic flash flood.
posted by Vimal Khawas at 10:42 PM
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