Brahmaputra water darkening
Massive landslides caused by a series of earthquakes in Tibet is darkening the Brahmaputra waters, satellite images show, and not Chinese construction activity as raised by a BJD MP in Lok Sabha
The accumulating debris has caused partial blockages at three locations, forming natural dams on 6 km of the river across a 12-km stretch in China. The worry for India is that these three dams may merge and eventually give away to result in a deluge downstream.
- Lab tests have established that the water has darkened due to turbidity typically caused by landslides. “There is no foul play involved. However, landslide-induced turbidity usually subsides within a week.
- A preliminary study by two researchers from Bengaluru-based National Centre for Biological Sciences (NCBS) and Ashoka Trust for Research in Ecology and the Environment (ATREE) shows that quake-induced landslides on the river continued for over three weeks, which probably explains the prolonged turbidity.
- The Yarlung-Tsangpo river cuts through the world’s tallest gorge between Gyala Peri and Namcha Barwa before merging with the Yigong-Tsangpo river and taking a 180-degree turn southward to flow into Arunachal Pradesh where it is known as Siang. Further downstream, major tributaries — such as the Lohit and Dibang — join the Siang to make it the Brahmaputra.
- The study by Chintan Sheth (NCBS) and Anirban Datta-Roy (ATREE) reported that images captured by the European Space Agency’s Sentinel-2 satellite on December 10 captured the landslide in progress as well as blockages of the Yarlung-Tsangpo river by debris at three locations in the Bayi district, Nyingchi County. The evidence puts to rest fears that dam construction and tunnelling work upstream the Yarlung-Tsangpo in China were responsible for the darkening of Brahmaputra waters.
- Blockage of river flow by debris is unpredictable as the area is extremely unstable and possibly still disposing rocks. Claiming that the present landslide was perhaps the largest estimated in 2017 and “catastrophically larger than the one in 2000,” the study underlined the urgency for real-time aerial monitoring to keep track of how the dams are evolving, and to prepare for any eventuality.
- In 2000, China had failed to warn India about the natural dam formation and its potential consequences.