Lower Subansiri project
By Our Staff Reporter
Guwahati, April 6: The NHPC has carried out a joint survey with the State Water Resources department 30 km downstream of the Lower Subansiri hydroelectric project on both banks of the Subansiri river, and has prepared a detailed project report for the erosion control works.The survey was conducted as per the recommendations of Joint Steering
Committee (JSC) and Technical Expert Committee (TEC). During the survey, an NHPC official said, stretches were identified on both right and left bank of Subansiri river which required protection and erosion control measures.
Subsequent to joint survey of the area, NHPC submitted its proposal and Detailed Project Report to Core Group of Assam, constituted to implement the JSC report concerning mitigation of downstream impact of Subansiri Lower Project. The proposal of NHPC, based upon Joint Survey Report, is under consideration for technical vetting by Water Resource department, Assam and approval of Core Group of Assam before its implementation.
An NHPC statement further clarified that M/s Flexituff, which is executing similar works by Water Resource department, Assam requested NHPC to carry out a demo work with Geo synthetic trap bags in line with similar works being carried out across River Rangadi near Dijoo Tea State.
Accordingly, Flexituff started their demo work on the right bank of River Subansiri near Dakhin Rupahi and the work is still in progress, with about 64 m stretch of bottom layer laid while the top layer is yet to be executed. Due to rise in river discharge on account of incessant rainfall in this area for more than a week, the bottom layer of geo synthetic trap bag has got submerged and the demo work has been discontinued temporarily.
The NHPC said that even before start of demo work, a secondary channel of Subansiri river was flowing into the already inundated banks of the Dakhin Rupahi even during the lean season of December/ January. With completion of this demo work, the flow of secondary channel commensurate with lean season discharge has been channelized into the main channel.
The NHPC said it has a detailed erosion control scheme for this area as per the joint survey report and the same shall be taken up during lean season after getting the ‘go ahead’ from the Core Group of Assam.
The portion of works done by Flexituff till date is intact and stable and no damage has been done. The site was visited by Officers of Water Resources department, Lakhimpur & Dhemaji, Assam who found the work under demo done so far is satisfactory, an NHPC statement said.
Further, due to increase in river discharge, discharge in secondary channel also increased which caused some erosion along the already inundated river bank. NHPC, on request of the villagers, undertook immediate protection measures along the critical zones so that there is no further damage.
“Till date there has been no damage to any household there, even the ones which were critically located along the banks since previous monsoon,” the NHPC said.