Deadly Flash Floods on the Rise in the Himalayas

February’s fatal glacial lake flood in the Indian state of Uttrakhand is a warning that more such tragedies are afoot, say experts.

On the southern slope of the Himalaya, the Indian state of Uttarakhand has long been prone to landslides, flash floods, avalanches, and cloudbursts. But, as a deadly flash flood in the region this past February indicates, such natural calamities are becoming more frequent and intense in the ecologically fragile region, say experts.

A rescue team struggles to locate people trapped in a tunnel in Tapovan, Uttarakhand on February 8, a day after the flash flood and resultant landslide. Photo courtesy of Press Information Bureau, India.

On February 7, 2021, a glacier detached in the Tapovan-Reni area of Uttrakhand’s Chamoli district and sent a rush of water, rocks, and silt into the Alaknanda River, resulting in a flash flood that killed more than 70 people and destroyed two hydropower stations, as well as bridges and houses along the river.

Irfan Rashid, an earth sciences professor at Kashmir University who is part of a group of scientists from various countries studying the exact cause of the Uttrakhand tragedy, points to a combination of warm temperatures — the Indian Meteorological Department has said January temperatures in Uttarakhand were the highest in six decades — and a glacier sitting on the steep slope at Tapovan-Reni. “On February 7, this glacier eroded due to warm temperature then fell down which caused flash floods in the area and caused massive devastation,” he says. “The incident took place because of rock-glacier detachment.”

Now, scientists say that climate change could cause February’s tragedy to repeat itself — not only in Uttrakhand but in other Himalayan regions of India like Jammu and Kashmir and Ladakh. Glaciers in all these states are melting at a significant pace — threatening rockslides, glacial lake outburst flooding, and other events that could cause devastating flash floods downstream.

“We have many glaciers in Jammu and Kashmir and Ladakh which are also sitting on steep slopes like in Uttrakhand, so we can’t rule out rock-glacier detachment here,” Rashid says. “We have so many glacial lakes in Jammu and Kashmir so if there is rock-glacier detachment, there will be more damage than in Uttrakhand.”

The Himalayas are classified as young fold mountains, formed a few million years ago when two of Earth’s tectonic plates collided and pushed together. Tens of thousands of glaciers run through the range, but where the last century’s rapid warming has melted glaciers, glacial lakes have formed. Frequent landslides can also cause these natural dams to rupture, causing the waters in these lakes to flood downstream communities.

A 2013 flood in Uttarakhand severely damaged at least 75 villages and washed away, submerged or otherwise affected an estimated that 400 villages across Uttarkashi, Rudraprayag, Chamoli and Tehri regions. Photo courtesy of Jan Vikas Sansthan (Oxfam India partner)

According to Shakil Ahmad Romshoo, another earth sciences professor at the University of Kashmir, the Indian Himalayas contain 12,000 glaciers and 2,000 glacial lakes, of which at least 200 are vulnerable to breaching. Glacial lake outburst flooding (GLOF) is the term scientists use to describe the event when the waters of these lakes breach their boundaries, creating flash floods.

“There is a potential threat of glacier lake outburst in Chenab valley of Jammu region and Zanskar area of Ladakh,” Romshoo says. This region has already experienced a sizable GLOF event in the recent past. In May 2015, a flash flood from a glacial lake in Zanskar damaged several bridges and buildings — and displaced more than 3,000 people. Kashmir, too, was hit by a similar flood in 2014 that killed around 300 people and damaged hundreds of houses.

Romshoo, who has done extensive research on glaciers in the Himalayas overthe last two decades, has been monitoring Kashmir’s biggest glacier, Kolahoi, which lies at an average elevation of 4,700 meters (15,400 feet). It is the main source of Lidder River whose waters become the tributaries of the Jhelum River in Kashmir.

According to a study in the journal Water, Kolahoi has lost 23 percent of its area since 1962 (from 13.73 square kilometers in 1962 to 10.49 square kilometers in 2018). “Kolahoi is receding at 20 meters every year,” says Romshoo, who also adds that the area is prone to earthquakes, which can lead to an increased risk of landslides and lake breaching.

Many residents of the Indian Himalayas fear that a combination of seismic activity and melting glaciers is putting too much stress on hydropower dams in the region. “We have several power projects in Chenab valley of Jammu region. The water dams could burst anytime due to frequent earthquakes, blasting, and fast moving of water by melting of glaciers,” says Muzafar Ahmed, a resident of the Kishtwar area of Jammu.

This concern hasn’t stopped the construction of new dams in the area. The Indian government has proposed the construction of eight new hydropower dams on the Chenab River and its tributaries. Construction work is underway on three of them.

Another Jammu University geologist, GM Bhat, suggests building small reservoirs for hydroelectricity generation. Any breach in these smaller water bodies would be much easier to control, he says. Unfortunately, small reservoirs do not address the increasing rate of melting glaciers. Tragic floods, like the region has been witnessing increasingly, “could arise anytime,” Bhat says.

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