Report of a blockade in the main stream of Yarlung Tsangpo river in southwest China’s Tibet autonomous region creating a barrier lake on Wednesday and chances of its bursting has compelled the district administration of Lakhimpur, Dhemaji and Majuli in Upper Assam to sound a flash flood alert to those living along the Brahmaputra, while a similar alert was sounded in the Siang belt in upstream Arunachal Pradesh.

The district administration has appealed to the citizens not to venture around the periphery of the river. The Tsangpo flows as the Siang in Arunachal Pradesh and the Brahmaputra in Assam.

The source said authorities in Tibet have launched an emergency response, calling for the safe evacuation of local residents with a clearing team already arriving at the site.

Pasighat MLA Kaling Moyong on Friday held a meeting on the preparedness with other officials. An emergency meeting has been called in the conference hall of the chief secretary in Itanagar on Friday with head of departments concerned to tackle the situation. A control room number has also been opened at 2222340.

On Wednesday, East Siang deputy commissioner Tamiyo Tatak issued an order on the Siang bank’s low lying areas to be alert and Arunachal East MP Ninong Ering wrote to external affairs minister and minister of state for water resources informing them about the situation unfolding in Arunachal Pradesh. Ering, in the letter, said the Chinese government was paying close attention to river blockage and appealed to the government to keep in touch with its Chinese counterparts.

According to the regional water resources department, the landslide struck early on October 16 and 17 near a village in Menling county, blocking the waterway.

An administration source in Dhemaji district said the blockage is 3,500m in length and 2,500m in width at the widest point, which is 70km downstream from Nuxia hydrological station in China. The current estimated storage capacity of the barrier lake is 500 million cubic metres, which is gradually increasing and if the point bursts or breaks off, the barrier lake with a volume of 700 million cubic metres, the immediate discharge is estimated to be 80,000 cubic metres per second. The landslide, which occurred on the left bank of the river, is bigger than the 2008 landslide.

According to the Central Water Commission, the impact on Assam would be minimal as the water level of the Brahmaputra is low.

The water level might cross the high flood level at Pasighat if the blockade breaches. Dhemaji deputy commissioner R.A. Korati said there might be temporary rise in water levels in the district. However, people in the riverine areas are advised not to venture into the Brahmaputra for fishing, swimming or collecting driftwood. The administration is prepared and has appealed to the people not to panic. NDRF personnel have been airlifted from other states.