Medium to big dams unavoidable for NE

GUWAHATI, Feb 21 – Small dams will not be sustainable in the NE region. Multipurpose projects with very safe designs of medium to big dams on the tributaries of the Brahmaputra will be an unavoidable option in the days to come.

This is the opinion of renowned water resources expert Prof Nayan Sarma of the IIT, Roorkee. He was speaking to The Assam Tribune.

Explaining his view, Prof Sarma, who is presently adviser to the governments of Himachal Pradesh, Bihar, Uttar Pradesh, Haryana, Rajasthan, Kerala and Orissa, besides the Central Government, on water resources development and management, said heavy sediment ingress from the watersheds results in fast silting up of the storage reservoirs of the region.

Besides, small dams have small storage space for flood control, irrigation and hydel power generation. Therefore, they cannot be used for multipurpose projects.

Small dams are viable only in stable geological areas like the European countries, where well-preserved watershed areas are available. Switzerland is one such country. Against this backdrop, one may add the gradience factor of the NE rivers. The example of Brahmaputra may be cited in this respect. The mighty river has a drop of about 3 kms when it enters India from Tibet.

After debouching in the plains of Assam, the river undergoes the process of massive sediment unloading which is the root cause of braiding of the river channel along with bank erosion, he said.

On the designs of the dams, Sarma, who is conducting research on water resources development and management for the past about 30 years, is of the opinion that utmost care should be taken in this respect and the latest technology for designing dams should be used. As per requirement, dams can be strengthened to resist earthquakes by providing wider dam base with a flatter downstream face slope and, or, by vertical pre-stressing of the dam, he said.