Glacier Retreat In Ladakh Could Spawn Three Glacial Lakes: Study

One of the largest glaciers in the Suru river valley in Ladakh has been retreating at a much faster rate in recent decades, new research by the Wadia Institute of Himalayan Geology has found. Should the glacier continue to melt at its current pace, it could lead to the formation of three glacial lakes, increasing the region’s risk to glacial lake outburst floods.

The Parachik glacier in the Suru river valley covers an area of 53 square kilometers, with a length of about 14 kilometers. Between 1971 and 1999, the glacier retreated at an average rate of two meters per annum, according to satellite imagery and remote sensing data collected by the Institute. Between 1999 and 2021, the glacier retreat accelerated considerably, rising to a rate of 12 metres per annum. Additional field surveys conducted between 2015 and 2021 show an even higher retreat of 20 meters per annum.

“Glacier retreat is a natural phenomenon, but the accelerated retreat that we are seeing in recent years is a matter of concern and can be linked to the effects of global warming,” said Manish Mehta, a scientist with the Wadia Institute and one of the authors of the paper. “Glaciers are the main supply of water for this region, so if it continues to retreat, it will worsen water scarcity issues.”

The Parachik glacier is located in the southern Zanskar ranges of the Western Himalaya. The Suru river is a tributary of the Indus and is considered a major source of water for Kargil district in Ladakh, which has already been experiencing drought-like conditions in some parts.

The study, titled Glacier retreat, dynamics and bed overdeepenings of Parkachik Glacier, Ladakh Himalaya, India was published in the peer reviewed journal Annals of Glaciology last month. Its findings add to mounting evidence that glacial retreat in the Himalayas could threaten not only water supply but make the region more disaster prone.

Study Findings And Risks

The Wadia Institute’s study used a combination of satellite imagery and field surveys of the Parachik glacier. A tool called the Himalayan Glacier Thickness Mapper (HIGTHIM) was used to estimate the depth, water volume of the potential lakes, and other topographical features of the glacier.

Since 2015, “it was observed (in the field) that the glacier front is continuously breaking, and ice-collapsing events are happening regularly,” says the study. In 2017, the front of the glacier, called the glacier’s “snout,” broke off and formed a temporary lake which later breached. An ice cave, which was located at the glacier’s snout in 2015, also collapsed by 2018.

Observations from the Parachik glacier, particularly after 2015, “suggested accelerated glacier demise,” the study says.

“Several features of the glacier have shown retreat. There are two features [we noticed], one is that the glacier is retreating, the second is that the ice is moving downwards due to gravity, which has caused the glacier to lose mass,” said Mehta.

Suru river valley, where the Parachik glacier is located, has 252 glaciers covering 11% of the river’s catchment area. Earlier research by Mehta found that glaciers in the Suru river valley region were losing their mass balance because of warming temperatures and reduced precipitation during the accumulation period, which typically lasts through the winter, from December to February.

Should the Parachik glacier continue to retreat, a modelled simulation shows that there is a possibility of three lakes forming around it, with depths ranging from 34 to 84 meters. A 2020 study found that there are more than 192 glacial lakes in the Ladakh region, holding around 61 million cubic meters of water.

While reconstructing the causes of a 2014 glacial lake outburst flood from the Gya glacier in 2014, they concluded that a “false sense of security” and overlooking risks contributed to the devastating impacts on infrastructure and livelihoods further downstream.

“There is an urgent need to generate glacial lake inventories that include small lakes by using high spatial resolution satellite imagery,” said the paper, adding, “Multi-criteria guidelines may help to systematically categorize the individual lake hazard.”

Glacier Management

Earlier this year, research by scientists from the Birla Institute of Technology and Science Pilani (Goa), the Indian Space Research Organisation (ISRO) and the Divecha Centre for Climate Change at the Indian Institute of Science found that except sub basins in the upper Indus river, all others showed a substantial loss in glacier mass, affecting water supply to the Indus basin. Future water supply issues due to glacier retreat could also force water sharing agreements like the Indus Water Treaty between India and Pakistan to be re-evaluated, the study had said.

“Glaciers located in lower reaches of Himachal Pradesh, like in the Sutlej basin or Beas basin, are retreating very fast, and have been for many years now. The Wadia Institute study suggests glaciers at high altitude, located in the Karakoram mountain range, have also started to retreat at a faster rate,” said Anil Kulkarni, a glaciologist and distinguished scientist at the Divecha Centre for Climate Change. “More water is going to flow from the upper Indus basin, and it very well feeds into our own observations about the Indus basin.”

In March, a Parliamentary Standing Committee took note of India’s retreating glaciers in a study submitted to the Lok Sabha. It found that for India’s over 9,000 glaciers, there was no repository of data that showed the volume of glacier loss between 1950 to 2020, or projections for glacier loss till 2100. It tasked the Department of Water Resources, River Development & Ganga Rejuvenation with setting up an overarching institution for glacier management, with instructions to revert on progress by June. No announcements of such an institute have been made yet.

Kulkarni agrees that India needs a dedicated institution to track activities in India’s cryosphere.

“It’s very unfortunate that we don’t have a centre like this, even though we have one of the largest cryospheres in the world. Various agencies are doing their work and approaching it from their own point of view, but there is no comprehensive understanding being developed. If this lacuna isn’t addressed, we will be faced with many issues in the future,” he said.

(Published under Creative Commons from Mongabay-India. Read the original article here)