Lake cleared; no flash flood threat to Arunachal, Assam

Lake cleared; no flash flood threat to Arunachal, Assam

China informed Indian authorities on Saturday that the artificial lake created in the Yarlung Tsangpo in the Tibet region due to erosion has cleared. The news has brought relief to Arunachal Pradesh and Assam governments, which had feared sudden rise in waters in the Siang and the Brahmaputra rivers.

Authorities in the two neighbouring states had issued a high alert and even started evacuating people likely to be affected by the possible flash floods in case of a sudden bursting of the blockage.

The Yarlung Tsangpo is called the Siang when it enters Arunachal Pradesh from Tibet Autonomous Region and is known as the Brahmaputra as it flows further downstream into Assam.

A Central Water Commission (CWC) official here told DH that the rising water had hit Tuting point, 20 km inside Indian border in Arunachal Pradesh at 11 pm on Friday and reported 13-metre rise in water level. However, the situation became normal on Saturday afternoon. The water had hit Pasighat further downstream at 8 am and the Siang river water level had increased by 3.5 metres till 1 pm.

“Thereafter water started receding at Pasighat and reached 152.74 metre, which is 20 centimetre below the warning level. The water level has also been found to be normal at Tuting, which is 406.5 metre.

Chinese authorities have informed the central authorities in New Delhi that the artificial lake, which was formed following the blockage created by erosion in Yarlung Tsangpo at Milin section in China on October 16, has cleared now. "So we hope water level will not rise further but we are keeping close watch on the situation,” superintendent engineer of CWC, Ravi Ranjan said.

The place where the erosion took place in China is about 280 km upstream from the Indian border.  

Based on information shared by Chinese ministry of water resources, the ministry of external affairs had informed CWC that in case of a breach at the blockage, the water would rush downstream at the speed of 80,000 cubic metre per second and may cause major damage.

Lack of info

The Centre rushed additional companies of NDRF personnel from Odisha to both Arunachal Pradesh and the neighbouring Assam districts, while IAF deployed its helicopters for rescue operations in case of serious flash floods like the one it faced in 2000. More than 30 people had died after a sudden rise in water in the Siang had wreaked havoc but authorities could not take timely action mainly due to lack of information from China.

India and China signed an MOU in April this year to share hydrological data of Yarlung Tsangpo. 

“Although the impact is likely to be less in our district as the Brahmaputra here is much wider, we have started shifting people from riverine areas to safer places keeping in mind the high volume of water likely to flow down from China,” deputy commissioner of Dhemaji district (Assam), Roshni Aparanji Korati, said.

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