GUWAHATI, Dec 30 - The Central government and the state governments of Assam and Arunachal Pradesh have drawn flak for their failure to assess the exact situation resulting from the blockage of the Yarlung Tsangpo/Siang about 400 km upstream of Pasighat. Three landslide-induced dams have come up on the Yarlung Tsangpo in Bayi district of the Tibetan Nyingchi county.In their bid to uncover the mystery of the abnormal turbidity of the Siang/Brahmaputra river, two scientists from India – Chintan Sheth and Anirban Datta-Roy – found that three landslide-induced dams were formed on the Yarlung Tsangpo following the November 17, 2017 earthquake, storing over one billion cubic metres of water.
Sheth and Datta-Roy have found that the Siang water was muddy a few days ahead of the November 17 earthquake. This was perhaps due to the glaciers releasing some moraine prior to the earthquake.
Himanshu Thakkar of the South Asia Network on Dams, Rivers and People (SANDRP), who has been studying the rivers of South Asian region for several decades now, said that breach in a landslide-induced dam on the Yarlung Tsangpo in 2000, led to a disastrous flood in Arunachal Pradesh on June 1 that year. That episode started about 53 days before the disaster, on April 9, 2000, due to landslides along a tributary of the Yarlung Tsangpo.
A scientist of China recently told Thakkar at an international meeting that China had made elaborate plans and preparations to breach that landslide-induced dam in 2000, but amazingly, failed to inform India and Bangladesh, the immediate downstream countries at risk, about the landslide. History seems to repeat, since the Indian government failed to put sufficient pressure on China then.
Significantly, while the 6.4-magnitude November 17 earthquake seemed to have triggered the landslides, the website of the India Meteorology Department that monitors the earthquakes impacting India, has no mention of the earthquake and its aftershocks, Thakkar said, adding that he had found detailed information about the nine earthquakes in this region during November 17-23, 2017 on the USGS earthquake site.
While China has failed to provide all the details of the current landslide to India, the Indian authorities – the Government of India, CWC and National Remote Sensing Agency and the governments of Assam and Arunachal Pradesh – have also failed to make necessary assessments using the remote sensing capacities that they have. They also failed to inform the people at risk and put in a plan involving geologists, hydrologists and experts in remote sensing and disaster management, Thakkar said.
“We do not have full and clear information about the amount of water stored behind the landslide dams and if the water storage is still growing or not. We need to urgently assess this. Though China has now promised to communicate about this to India, the fact remains that they had not done this in the past. Even in the current episode, they have provided first bits of information, that too incomplete, over a month after the earthquakes.
“Unfortunately, Indian authorities are yet to show the necessary alertness and urgency in the matter. Lakhs of people in Arunachal Pradesh and Assam are already facing the consequences of the muddy Siang and Brahmaputra waters, while a looming risk of the consequences of any breach in the above dams are also haunting them,” said Thakkar.
Neeraj Vagholikar of the environmental research and advocacy group Kalpavriksh, said until scientists Sheth and Datta-Roy provided the first credible report based on satellite imagery analysis, there was nothing substantial in the public domain on this issue. It is surprising and disappointing that the country has not been able to put to better use its scientific prowess to analyse and communicate transparently to the people about these developments.
While we can hope for better communication between India and China on this issue, the expertise also exists within the region to work proactively on this. For example, the Assam Remote Sensing Agency can collaborate on a priority basis with IIT Guwahati and come out with a clear analysis of the landslide dams, including modelling a dam-break analysis, he said.