Landslide blocks river, sparks dam break fears in Sikkim

Photo of Reservoir behind the landslide dam posted on FB by Ujjwal Khawas

Vishwa Mohan | TNN | Aug 19, 2016, NEW DELHI: The Central Water Commission (CWC) on Friday alerted the Sikkim government, the National Disaster Management Authority (NDMA) and the public sector hydroelectric company NHPC for possible dam break scenario of an artificial lake on river Kanaka. The artificial lake was formed on Kanaka - a tributary of Teesta - in Sikkim due to blockage of the river after a major landslide on August 13.

Apprehending the dam break, the Commission asked the state government, NHPC and NDMA to take suitable precautionary measures on their parts.

It noted that the water of the lake has already started flowing above the crest of the landslide dam whose approximate height is about 65 meters.

Report of the CWC said the necessary study has been carried out in the Commission to estimate the possible flood peak and additional rise in river water level at different locations downstream of the landslide dam in the event of a dam break.

River Kanaka joins river Teesta about 3 km upstream of Mangan. The location of landslide dam on river Kanaka is about 4 km upstream of Teesta and Kanaka confluence.

The operational hydroelectric project of NHPC, Teesta-V, is situated on river Teesta about 21 km downstream of the present landslide dam.

"The live storage of Teesta-V, in consultation with the concerned project authorities, may be utilised to moderate the landslide dam breach flood in the reach of river Teesta, downstream of Teesta-V hydroelectric project", said the CWC in its report, sent to the multiple agencies.