The death toll in the Sikkim flash floods touched 14 on Thursday morning while 102 people are still missing, said Sikkim government sources. The floods occurred after a cloudburst over Lhonak Lake in north Sikkim on Wednesday.
Of the 14 people, 10 have been identified as civilians. Three among them were washed up in north Bengal. As for Army personnel, 22 people are still missing while one was rescued later.
Over 3,000 tourists from various parts of the country are stranded in different parts of Sikkim, Sikkim Chief Secretary V B Pathak told PTI, adding that several workers employed with Teesta Stage III dam in Chungthang were also stranded inside the tunnels of the dam.
The most number of missing people are from Chungthang in Mangan district, and Dikchu, Singtam in Gangtok district and Rangpo in Pakyong district, he added. The sudden release of water from the Chungthang dam resulted in water levels going up to 15-20 feet high downstream.
Disaster declared, schools shut
The Sikkim government has declared the natural calamity as a disaster and all schools located in Mangan, Gangtok, Pakyong and Namchi districts will remain closed till October 8.
The flash floods caused huge damage to the state's infrastructure, as 14 bridges collapsed. Of them, nine were under the Border Roads Organization (BRO) and five others belonged to the state government. A steel bridge at Singtam, known as Indreni bridge, 30 km from the state capital Gangtok, has been completely washed away by the floods.
Parts of National Highway-10, the main link between Sikkim and the rest of the country, were washed away. The state government has decided to construct Bailey bridge with help from the Army and NHIDCL to ensure that essential supplies reach people.
The administration has set up several relief camps in Singtam, Rangpo, Dikchu and Adarsh Gaon to house the displaced people where hundreds are taking shelter. Chief Minister P S Tamang visited Singtam and took stock of the situation.
What caused the floods
According to the National Disaster Management Authority (NDMA), a combination of excess rainfall and a Glacial Lake Outburst Flood (GLOF) event at South Lhonak lake in North Sikkim could have triggered the flash floods.
A statement by the NDMA said the Himalayan ranges are host to many glacial lakes, estimated through remote sensing techniques at about 7,500 and of these, Sikkim has around 10 per cent of which nearly 25 are assessed to be at-risk.
"While scientists are investigating the exact cause of the flash flood, the primary reason for the sudden surge appears to be a likely combination of excess rainfall and a GLOF (Glacial Lake Outburst Flood) event at South Lhonak lake in North Sikkim," it said in the statement.
The lake is at a height of 5,200 metres, with a towering ice-capped feature at about 6,800 metres to the north of and in close proximity to the lake.
Satellite images received from the ISRO at 0600 hours on Wednesday, reveal the draining out of more than half the lake, most likely as a result of an avalanche from the ice- capped feature.
The Central Water Commission's monitoring stations said the first surge of water was 19 metres above the maximum water level at Sangkalang at 0130 hours and 4 metres above the maximum water level at Melli at 0400 hours.
Meanwhile, rescue efforts are hit by continued snowfall in upper reaches and rainfall and clouds in lower reaches. However, the NDMA said consistent efforts are underway to assist the state government in all manner possible.
Recently, in order to mitigate the impact of a GLOF event in these lakes, an NDMA-led expedition in the first week of September 2023 had surveyed two at-risk lakes in order to eventually deploy early warning systems for real-time alerts. At the next stage, the NDMA has planned to instal early warning systems for real-time alerts at most of 56 at-risk glacial lakes in India.
Efforts to expand the mitigation programme are being expedited, while sustained investigations into the causes of this event are underway, the statement said.
(With PTI inputs)