(Above: Lower part of the Dzongu Landslide, Photo from Save the Hills)
According to a number of reports[i], at around 1230 hours on Aug 13, 2016, a massive landslide completely blocked the flow of Kanaka (Rongyoung) River near Mentam village in Dzongu region in North Sikkim. A hillock called “So Bhir” came crashing down, it is reported. The Landslide dam is about 50 m high, about 45 m wide, the landslide top point is about 900 m above the river. Darjeeling Chronicle reports, the river downstream is totally dry as the water has started collecting behind the landslide dam (that situation seems to have changed on 14th Aug morning around 830 am).
An earlier update said: “The dam is about 150 ft wide and growing bigger, due to this about Five houses in Mentam has submerged. About 300 mtrs of Road is damaged and a bridge is submerged. All people of Mentam has been evacuated and two relief camp had been setup.” The Times of India[ii] reported: “The reservoir (of Teest V project of NHPC) has been emptied as a precaution and machines have been shut down. Kanka bridge is already submerged and about 300 metres of road washed away… The threat looms on Dikchu, Makha, Singtam and Rangpo. If the dam breaks, Teesta Bazaar and 29 Mile will also be affected. An official said once the dam starts leaking, the thousands of residents of Teesta Bazaar and 29 Mile will have barely three to three-and-a-half hours to get to safety.”
Google Earth Image of site of the Dzongu Landslide
Reports suggest that the Landslide started on Aug 2 (Save the Hills says it started on Aug 8) and has been growing in size since than and ultimately blocked the path of the river. The growing size of the water reservoir behind the landslide dam could be a major risk for the downstream area when it breaches.
There are a number of dams and hydropower project on Teesta downstream from the dam right upto the irrigation barrage in Bangladesh. Any cascading effect could be catastrophic. A SANDRP map of Teesta Basin projects[iii] provides information about the projects that could be in the path of the river downstream from the landslide dam.
There is a reassuring message (along with some very good photos), though on Save the Hills Blog[iv]: “From our side, we are in touch with representatives of the Govt both at the Centre and States and members of the community in Dzongu, North Sikkim and continuously exchanging information. Luckily, there is no rain in this region and those likely to be immediately impacted have been evacuated.”
Latest Update: The latest update on Save the Hills site today (Aug 14 2016) morning[v] says: “No casualties so far. Administration has started ‘miking’ along some areas of NH10 which might be affected if the landslide dam bursts or overflows, this entails passing the message on vehicle borne PA systems… NDRF has been dispatched to the area. Geologists and Disaster Management officials will survey area today.”
Darjeeling Chronicle[vi] posted this on their facebook page at about 8.45 am on Aug 14, 2016: “Dzongu Landslide Update: Good News – Water Starts Flowing Over the Debries. Thinlay Namgyal Lepcha writes, “Accumulated water has started flowing over the debris this morning. The breath of the debris looks quite wide and hence chances of a sudden burst seems minimal.””
Post Script: For an update on this landslide dam, see: https://sandrp.wordpress.com/2016/08/16/teesta-landslide-dam-in-dzongu-river-overflows-over-dam-but-risk-continue/
[i] http://savethehills.blogspot.in/2016/08/landslide-dam-in-north-sikkim-on-kanaka.html, https://www.facebook.com/TheDarjeelingChronicle/posts/723738141097303, Videos of the landslide: https://www.youtube.com/watch?v=ln3fZINno34&feature=youtu.be, https://www.facebook.com/TheDarjeelingChronicle/videos/723734521097665/, http://blogs.agu.org/landslideblog/2016/08/13/dzongu-1/