Kanaka river natural dam under control- but release of water in slow manner is necessary

KalimNews, Mangan, August 20: The water of the natural dam in Kanaka river should be released in a controlled manner because sudden release may cause damages to land upstream. The experts from Mines and Geology was of the opinion that the that the current hill slide had multiple planes of fractures and further landslide are a high possibility. The landslide is still active and future landslide cannot be ruled out, an IPR press release stated. 

According to the information and press release made by the IPR Sikkim, a team of  technical experts led by State Relief Commissioner, Mr. Tsegyal Tashi, and consisting of Mr. D.P Sharma, Secretary of Mines, Minerals & Geology Department, experts from State Disaster Management Authority, Dr Ravindra Singh, National Disaster Management Authority (NDMA), New Delhi,  Geographical Survey of India ,Central Water Commission, NHPC, Mines, Minerals & Geology Department Sikkim, Army Engineers and from Border Road Organization (BRO), accompanied by District Collector (North) and other officers of the district administration conducted an in-depth survey of the dam over the Kanaka river in Dzongu today.

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According to their study, the landslide was caused due to natural  fractures in the steep  hill slope which was composed of loose soil and fine sediments compounded by seepage of river water in the fractures.

The Central Water Commission was of the opinion that volume of water in the lake was about 7 million cubic meter and it was necessary to drain the water out of the lake to resolve the situation.

Press release has stated that on August 13th due to the landslide at 4th Mile, the river Kanaka had been choked for about 12 and half hours creating a landslide lake and a reservoir estimated to about 65metre in depth with a maximum width of about 200 metre and 3kilometer in length. 

The State Mines and Geology Department has prepared a detailed cross section of the natural dam and found that the dam base is about 400 metre in width at the bottom. The estimated volume of debris collected on the river bed is more than 1.2 million cubic metre. There are different estimates on the pondage of the water and it is approximately 6 million cubic metre as per the experts.

According to Chief Engineer, NHPC the Teesta Stage V dam is located about 21 kilometre downstream this landslide dam. The reservoir of Stage V dam has sufficient storage capacity to store the excess water released from the lake at the calamity hit zone.. NHPC is of the opinion that the Teesta Stage V will be able to absorb the excess water released in case of the  breach of the artificial lake and their  reservoir could thus cushion the outflow of water thus saving the damages to properties downstream of the Stage V dam where the important town of Singtam and Rangpo of Sikkim is located. NHPC was also of the opinion that since the height of the hill from which the debris has fallen is more than 800 metre, the compaction of the debris into the river valley was strong enough to withstand the water in the lake.

Considering the views of the various experts, it was agreed by all the the  water was required to be drain out from the lake. In order to carry out this procedure it was decided to use heavy machinery to extract the debris from the mouth of lake in a very controlled manner. The entire procedure is to be carried under strict supervision of the senior engineers from State government under the technical guidance of the NHPC specialists and GREF engineers. The road construction machines could be provided by the GREF also for this effort. Currently road department has deployed two heavy construction machines at the site for construction of road till the lake top. Once the road is constructed these machines could start the procedure of widening the opening of the rivers at the mouth of the lake.

The entire operation will be monitored by the District Collector and the administration to ensure maximum safety and precision while doing the work.

The NDMA expert also agreed to the idea of slow opening the width of the mouth of the river and increasing the volume of discharge of waters to drain the water over due course of time. He was of the opinion that the discharge should be increased slowly and the procedure should be carried in a very controlled manner.

The Relief Commissioner stated that a meeting to discuss the ways and means of carrying this surgical procedure of extraction of water will be fixed on Monday and all the experts were asked to attend to finalize the procedures.

The Relief Commissioner also visited the relief camps and handed the ex-gratia to the affected families whose clothes and belonging was lost due to flooding of their houses. He expressed his happiness with the work of the district administration and applauded the efforts of the district administration in relief and restoration of the affected villages of Mantam and other cut off areas of Upper Dzongu. He urged everyone to coordinated in the resolving the current situation.

Later in the day the Relief Commissioner, District Collector, NDMA expert, Mines and Geology team also visited the damaged areas of Rafong Nalla near Mangan. The DPR of the same is currently under consideration with NDMA.