High altitude Glacial lakes are now at major risk In Sikkim Himalaya due to the climate change over a last few decades. In a recent study, Researchers have identified two of them to be at high risk, which may cause potential flash floods soon in the states of Sikkim.
South Lhonak Lake at North West Sikkim area and Gurudongmar Chho at North Sikkim area, have high chances of bursting into floods (GLOF) because of their rapidly increasing volume and weak moraine structure. The nearest villages and the adjacent exposed Army Camps near these lakes are now at terrible risk. Study says that climate changes lead to decreasing glacier volume and swelling of these lakes.
South Lhonak Lake collects molten glacier mostly from South Lhonak Glacier and partly from its adjacent glaicers, North Lhonak Glacier and Main Lhonak Glacier. Additionally the loosely weak moraine bed structure enhances the process of inter-moraine ice melting, resulting rapid increasing of approximately 145% of the lake area over past 40 years.
According to the study, though it is the second highest Glacial melt lake in Sikkim for now (largest lake is Khangchung Chho at extreme East of North Sikkim area which comparatively has increased 47% of it's area over past 40 years), but in the next two decades it is going to be the largest lake if the present rate of it's abnormal increase remains unchanged.
Gurudongmar Lake in 2016 (Photographed by Sanjib Das in 2016)
Another study from The State Climate Change Cell, under Sikkim State Council says that if the overflow occurs at South Lhonak Lake, the water flow would take just 3-4 hours to reach the first habitat in that region.
The investigation has also found a total of 21 lakes out of 472 lakes are suscpetible by using a method, Analytic Hierarchy Process (AHP) which has increased their area during the period of 1972-2015. It reveals that in consecutive five different decades how the area of these lakes have expanded with volume (see Chart for reference). Among these lakes, Khangchung Chho (Lake 0044) is the largest end moraine-dammed lake and the second largest glacial lake in Sikkim is South Lhonak (Lake 0001) with an area of 1029 km2. Gurudongmar 2 (lake 0047) and Pandon Chho (lake 0331) have also experienced a remarkable growth over the last two decades. North Lhonak (lake 0002) and Mashya-Tso (lake 0048) have experienced a moderate growth but still measurable areal increase.
Areal change of lakes susceptible to GLOF between 1975 and 2015 (as provided in the study)
Highlights
1.
Two of the Sikkim Himalayan high altitude glacial lakes are recommended as high chances of bursting into floods.
2.
The South Lhonak Lake is increasing rapidly with its size (145% in 40 years) and water volume (increasing rate of glacial melting).
3.
Lake Gurudongmar Chho is also at high risk.
4.
The nearest villages and the adjacent exposed Army Camps near these lakes are now at terrible risk.
5.
Study says, if the overflow occurs at South Lhonak Lake, the water flow would take just 3-4 hours to reach the first habitat in that region.
6.
Climate change is the main cause of glacial melting as they reported.
As given in the Fifth Assessment Report (ARS) of the Intergovernmental Panel on Climate Change (IPCC), average surface temperature of land and ocean has increased by 0.65-10.06 °C during the years 1980-2012. They have mentioned that the last 30 years were the warmest out of the last 1400 years in the Northern Hemisphere.
Last year the Sikkim Government (SDMA) invited 'ICE STUPA' for a Project, to install a syphoning system to drain the lake to a safer level until other measures are taken up. The project was led by Sonam Wangchuk, the real life inspiration behind the character "Phunsuk Wangdu" from the famous Bollywood movie "3 Idiots" along with his three team members.
The team successfully installed three pipelines over high altitude Lhonak Lake (5200m) which could suck out 13 million litres of water (150 litres per second) per day from the lake. As a result of this, by the end of winter last year, the 2Km long lake was lowered by up to 1.5m as per expectations.
ICE STUPA team installing Syphonic system at South Lhonak lake in 2016 (Photo Courtesy: ecologise.in)
For reducing the threat they also planned to continue with more pipeline syphoning systems over the lake during the present year for draining out at least 25% of the floodable water content of the lake.
According to Mr. Wangchuk, "This would most probably become the first project of its kind and scale in Asia (possibly the world)."
This article is based on the following research paper
Aggarwal, Suruchi, S. C. Rai, P. K. Thakur, and Adam Emmer. "Inventory and recently increasing GLOF susceptibility of glacial lakes in Sikkim, Eastern Himalaya." Geomorphology 295 (2017): 39-54.
DOI https://doi.org/10.1016/j.geomorph.2017.06.014
