June 19, 2020 11:02:26 pm
There is currently no threat of a breach at a lake in China which has caused flash floods downstream in Himachal Pradesh in the past, scientists monitoring the situation said.
A breach of Parechu lake, a depression along the Parechu river in the Tibetan Himalayas, which filled up after a landslide dammed the river, caused flash floods in the Sutlej basin in Himachal in 2005. Ever since India has been monitoring water levels of the lake through satellite imagery during summer and monsoon to stay prepared in case of a repeat of the tragedy.
In 2013, water accumulation in the lake had increased after the inflow of water exceeded the outflow, causing an alarm in Himachal, but there was no breach. Officials said the water spread of the lake has been stable for the past several years, and according to a report by the state centre on climate change, last year’s satellite data showed slight accumulation in the lake but a normal flow of water.
Dr S S Randhawa, principal scientific officer at the centre, said that this year’s satellite data is currently being received from the National Remote Sensing Agency in Hyderabad, and is yet to be analysed. Alternatively, water levels along the Sutlej are also monitored by the Central Water Commission. An official from the commission said that the lake has mostly been “lying dormant” since it burst in 2005, and poses no threat as of now.
The Parechu river enters Himachal from the east near Kaurik in Spiti, and soon joins the Spiti river flowing from the west. From here, the Parechu-Spiti tributary flows southward for around 50 km before joining the Sutlej which enters Himachal from China near the Shipki La pass in Kinnaur.
The CWC monitors the Sutlej water levels in Kinnaur and also receives upstream data from Zhada in China, an official said, adding that the concerned authorities in China have been cooperative in sharing this data.
2005 flood washed away roads, bridges
The flash flood in 2005 had claimed no human life, but caused property damage to the tune of Rs 610 crore, according to the state disaster management authority. It washed away 10 bridges, 11 ropeways, and parts of the old Hindustan Tibet road, including a 10-km stretch between Wangtoo and Samdo. It also damaged link roads and other motorable and foot bridges.
The region also witnessed similar flash floods back in 1975, when an earthquake created a blockage on the Parechu River between Kaurik and Sumdo. It led to the formation of a temporary lake which burst two months later causing floods in the area.
Recipe for disaster
Climate change-induced glacial lakes are forming rapidly in the Western Himalayas, posing great danger to downstream areas, according to a recent study by the state centre on climate change. It said that the extent of a majority of glaciers is changing rapidly, leading to an “alarming increase” in the formation of moraine dammed lakes. When such a lake bursts, consequences down the stream can be disastrous.
Researchers were able to map 562 glacial lakes in the Sutlej basin, 242 in the Chenab basin, 93 in the Beas basin and 38 lakes in the Ravi basin.
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