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Brahmaputra erosion destroys nearly 4,000 sq km of Assam land

Last Updated: Thursday, February 4, 2010 - 11:37

Guwahati: The mighty Brahmaputra has wiped
out nearly 4,000 square kilometres of area at a rate of 80
square kilometres per year, destroying more than 2500 villages
and affecting more than five million people in Assam.

Assam`s Water Resources Department has identified 25
vulnerable and very severe erosion-prone sites and estimated
that the Assam valley portion of the Brahmaputra has lost
approximately 7.4 percent of its land area due to river bank
erosion and channel migration.

Experts from Assam and the USA, who have formed a joint
committee, christened The Committee for Developing Mitigation
Strategies for Brahmaputra River Basin Flood and Erosion
Problem, have come forward with a set of short and long term
measures to address the problem and develop cost-effective
solutions.

The experts have pointed out that the key factors in
causing the river extremely unstable at many reaches are
`aggradation` (raising of the river bed due to sediment
deposition), intense `braiding` and large water discharge.

They pointed out that till now both short and long term
measures to tackle the erosion problem had been done only on a
piecemeal basis during emergency situations depending on
availability of funds.

Experts in the committee are: Retired professor of
civil engineering, University of Alaska, Dr Arvind Phukan,
senior project manager at Woolpert, Virginia, Deva Borah,
chairman of the Surface Water Hydrology Committee of the
American Society of Civil Engineers Ananta Nath, Assam Water
Resources Department`s senior engineer Rajib Goswami and
professor of civil engineering in IIT, Guwahati, Chandan
Mahanta.

They have recommended phase-wise solution for the
mitigation of erosion by including a combination of measures
including strategic dredging, protection of erodible bank
materials with anchored bulkhead or tie back sheet piles,
spurs, toe and bank revetments.

Improvement of data quality and quantity by extending
rain, flow and sediment monitoring network using
state-of-the-art equipment and consider physical modelling to
study severe and potential scour sites and their control have
also been suggested by the experts.

The experts further recommended development of advanced
and efficient computational tools capable of utilizing the
detailed hydro-meterological data and predicting realtime
flooding and hydraulic characteristics of the river for
planning and designing effective flood and erosion control
measures.

The committee has suggested taking advantage of modern
technologies such as satellite image-based morphological
study, studying of successful erosion control measures in
major rivers of the world and feedback from international
experts among steps to stem the erosion in the Brahmaputra at
the earliest.

The committee suggested strengthening and monitoring of
anti-erosion measures already taken up at Majuli Island and
severely eroded towns along the river and armouring existing
embankments located at urban and other strategic locations.

PTI

First Published: Thursday, February 4, 2010 - 11:37
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