GUWAHATI, Oct 9 - A Gauhati University (GU) lady research scholar in environmental science has proposed a scheme for reviving the degraded Kolong river with a natural channel design approach, which is basically a hydro-ecological approach. The Kolong is at present gasping for life because of the act of severing its link with the Brahmaputra in the name of an engineering solution to the increasing flood hazard attributed to it in the aftermath of the Great Assam Earthquake of 1950.
The research scholar claims that she has developed an elaborate hydrological database containing peak and design discharges for 10 years, 25 years, 50 years and 100 years, bank-full discharge, stage-discharge rating curve, basin runoff etc., for the Kolong river and its tributaries.
Moreover, she says the hydraulic geometry relationships (that is � relationship maintained by river flow with its velocity, channel width as well as depth) of the Kolong river are also adequately explored.
The findings of her research, which was sponsored by the Department of Science and Technology, Government of India for the past five years, under the �Inspire Programme for PhD Research,� were published in several scientific journals, including the leading Current Science, in its August 25, 2017 issue.
Minakshi Bora, the research scholar, says the morphological study of the river channel, its shifting pattern, rate of erosion and deposition etc., were carried out through field surveys and analysis of spatial databases under GIS environment. Finally, she said, based on the baseline geo-environmental setting and analysis of fluvial, ecological and socio-economic databases, a scheme for reviving the degraded Kolong river has been proposed.
The Kolong river, a distributary (suti in Assamese) of the Brahmaputra was blocked in 1964 by erecting an earthen embankment at its take-off point at Hatimura, to save Nagaon town and its adjacent areas from the havoc of flood. This embankment not only turned Kolong into a diminishing river, but also adversely impacted the large number of wetlands connected with this river system.
The Kolong, with a total length of about 250 kilometres (kms), has branched out from the Brahmaputra near Jakhalabandha, about 77 km upstream of Nagaon town, and has met it again at Kajalimukh near Guwahati, in a joint channel with the Kopili river, a major south bank tributary of the Brahmaputra. Kopili has met Kolong at Jagibhakat Gaon in Morigaon district.
Bora maintains that it is high time to undertake a holistic river restoration programme for the Kolong river based on state-of-the-art knowledge and scientific know-how currently available on the subject. River restoration, in scientific parlance, is the act of working with a degraded river or stream in order to revisit its pre-disturbed condition. Although in countries like USA, Japan, China, Russia and in some parts of our own country too, river restoration is rather a familiar concept, it is still non-existent in Northeast India, despite widespread degradation of its river systems.
The Kolong was at the root of the prosperity of a vast Nagaon district area till the early 1960s. The alluvium deposited by the river during the flood season used to naturally fertilize the adjoining floodplains.
The river, with a network of biologically rich, economically resourceful and hydrologically significant wetlands, facilitated development of an ecologically rich natural ecosystem where a large variety of fishes and other aquatic flora and fauna, including river dolphins, flourished. Steam boats too once plied on this river, adding to the economic vigour of the people living by it, maintains the research scholar.