Guwahati, India: The submerged heaps of sand deposits in the Brahmaputra river system are at the root of the river’s unremitting bank erosion process, observed river engineer Prof Nayan Sarma. Prof Sarma is presently the Head of the Department of Water Resources Development & Management, Indian Institute of Technology (IIT), Roorkee.
“From a satellite imagery based analysis by my team at IIT Roorkee, it could be estimated that a total land area of about 1700 square kilometres has been eroded by the Brahmaputra and its major tributaries during the period 1990 – 2007,” Prof Sarma said. This land loss is accompanied by sharp rise in braiding intensity of the Brahmaputra, which is reflected in increased flooding and overtopping of the flood embankments.
To him, the annual average sediment load of the river has now reached a value of about 800 million tonnes, a good part of which gets deposited in the riverbed during the receding flood stage.
He maintained that it is of prime importance to urgently take up the process for tackling the channel instability behaviour of the Brahmaputra River to achieve gradual channelisation in a phase-wise manner. This can be achieved by adopting a strategic approach to systemically bring about subsidiary channel closures combined with effective stream bank erosion control. Such a strategy will require adoption of innovative sedimentation inducing river training techniques.
He argued that for more durable permanent solution, it is prerequisite to undertake effective catchment area treatment extensively through implementation of soil conservation measures. The approximate time frame of about 30 to 40 years may be required for achieving some sort of reasonable stabilisationof the river morphology.
Source: Assam Tribune