With 1,600 glacial lakes, Himachal faces flood risk
SHIMLA: The glacial lake outburst flood (GLOF) at Joshimath in Uttarakhand has once again put the spotlight on the 1,600 glacial lakes that have formed in Himalayan river basins in Himachal Pradesh and pose a threat to settlements and ecology in case of a rupture.
The formation of these lakes, which vary in size from five to 10 hectares, has been primarily attributed to global warming, climate change and local factors. SS Randhawa, principal scientific officer at the State Centre on Climate Change, said, “The situation in Himachal Pradesh is no different from that in Uttarakhand. The lakes pose a grave threat to all that lies downstream.” “Glacial lakes that are over 10 hectares in size pose a greater threat and have to be monitored regularly,” Randhawa said.
2005 lake burst
An artificial lake formed in a geomorphic depression in the course of Parceehu River had burst in 2005 when rapid glacial melting in summers had increased the water level in the river. The lake burst had caused extensive damage along the Sutlej River. The resulting flood had washed away at least 12 bridges in the Kinnaur-rampur belt and several villages, including Leo village in Kinnaur. Sutlej’s water level had increased by an unprecedented 25 metres. The damage to government properties was estimated to be around ₹800 crore.
Rapid increase in lakes over last 5 years
Himachal Pradesh Council of
Science and Technology monitors lake formation in river basins through remote sensing and satellite data. Studies have revealed that rapidly melting glaciers have led to the formation of numerous lakes in the basins of perennial Himalayan rivers, including Sutlej, Chenab , Beas and Ravi and their tributaries, over the last five years. The number of lakes has been increasing at an alarming rate, say studies.
Data collected between 2015
and 2018 shows that there was a 36% drop in lakes in the Beas basin. However, there has been a 32% increase in lakes in the Chenab basin, 94% increase in the Ravi basin and 97% increase in the Sutlej basin.
Sutlej has most glacial lakes
An analysis of images captured between 2015 to 2018 revealed that the Sutlej basin has 769 lakes, of which 663 are below five hectares, 57 lakes have an aerial range between five to 10 hectare and 49 lakes extend over 10 hectares. An additional 127 lakes have sprung up in the basin since 2017, indicating an overall increase of around 16% lakes in the basin. In the Chenab basin (Chandra, Bhaga, Miyar), 254 lakes were delineated, of which 64 were in the Chandra sub-basin, 84 in the Bhaga subbasin and 106 in the Miyar subbasin. The Chenab basin had 192 lakes in 2015. However, the count had increased to 254 in 2018. Notably, only 55 lakes had been reported in the Chenab basin in 2001.
Aerial measurements indicate that 240 lakes are less than five hectares, 10 between five to 10 hectares and four extend over 10 hectares, which indicates a 20% reduction in bigger lakes.
35% decrease in Parvati sub-basin
There was a 35% decrease in lakes in the Parvati sub-basin in 2018 in comparison to 2017. Scientists attribute this anomaly to the high cloud cover in the Jiwa basin. Of the 65 lakes in the subbasin, 58 lakes were small, with an area below five hectares, four lakes had an aerial range between five and 10 hectares and three lakes had an area of more than 10 hectares in 2018, indicating an overall reduction of around 36% for small lakes and a drop of 25% in case of bigger lakes since 2017. No change was apparent in lakes with an area between five to 10 hectares.
In the Ravi basin, 66 lakes were documented in 2018, while only 54 had been mapped in 2017. Studies indicate three lakes were over 10 hectares, two lakes were between five to 10 hectares and 61 lakes were spread over less than five hectares.
The glacial burst in the Chamoli district of Uttarakhand may well be nature’s way of telling humans that it can strike back when the ecological balance is destroyed. High-intensity stone quarrying, frequent blasting of mountains and digging of tunnels through the base of the fragile mountain system for the back-to-back underconstruction dams, each on the Rishi Ganga and Dhauli Ganga rivers, have played havoc with the local ecology. To be sure, the exact cause of the disaster that unfolded on Sunday is still being determined – but there is no doubt that the impact would have been far less with more prudent development of projects in the region.
The climate crisis may have aggravated the situation. A new report by Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) said that 36% of the volume of glaciers in Hindu Kush Himalayan (HKH) region will be gone by the end of 2100 even if the world manages to keep the temperature rise within the 1.5 degree Celsius target of the Paris Climate Agreement. Though the disaster region does not fall in the HKH, the findings confirm other studies on faster melting of glaciers feeding the perennial Ganga from the upper reaches of Uttarakhand and China.
Data from the Indian Space Research Organisation’s resource centre on Himalayan glaciers reveal that melting of the glaciers in the Central Himalayan catchment area, where Chamoli falls, has increased in the first 20 years of this century. Research based on the study of 650 glaciers, spanning 2,000 km and published in Science Advances in June 2019, said that glacial melting has doubled since 2000 as compared to 1975-2000. The faster melting of Ganga glaciers will impact the livelihood of close to 600 million people living in Ganga river basin, extending from Uttarakhand in the north to Bangladesh in the south.
Glacial melting and bursts are well-documented. But little attention has been paid to the damage caused to local ecology and loss of forest cover in the upper reaches of the central Himalayas by building hydel dams and construction of wider roads (read: Char Dham road project) overlooking environmental norms. Villagers of Raini in Chamoli, now the epicentre of Sunday’s disaster, had petitioned the Uttarakhand High Court in May 2019 against illegal stone quarrying on the Rishi Ganga river bed, blasting of mountains and improper muck disposal by contractors engaged for construction of the Rishi Ganga hydel project. The high court asked the district magistrate of Chamoli to submit a report; and he found some of the allegations true. Not much happened after that.
The upper reaches of Uttarakhand, source for several small riverine systems feeding the Ganga, already have 16 dams and another 13 under construction. The state government has proposed another 54 dams to harness the hydel energy potential of these rivers. On the Dhauli Ganga river, eight new hydel projects are proposed in addition to National Thermal Power Corporation’s Tapovan project, which was badly damaged in Sunday’s flash floods. Geologists say that such heavy drilling of a young and understudied mountain system such as the Himalayas and loss of massive green cover for these dams are causing irreparable damage.
What should be an eye-opener is that rarely, anywhere in the world, do two such big disasters in a region take place in a short duration of less than a decade. A similar flash flood caused by a glacial lake burst ravaged the Kedarnath Shrine at the peak of the pilgrimage season in 2013, killing close to 3,000 people and leaving thousands missing. There was no such human rush in Chamoli fortunately because Rishi Ganga and Dhauli Ganga are small rivers. All those who died or are missing are workers at the two hydel projects.
There is enough data to suggest that the number of severe flash floods due to glacial melt in Uttarakhand has increased post-2000 and the reason, experts say, is the sudden spurt of environmentally-unfriendly development activities. If the present pace of Himalayan destruction continues, a future disaster will be devastating. Nature will strike back again. Damaging today and repairing tomorrow is not an option. India has only one option — save the Himalayas.