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Friday, March 05, 2021

Explained: Glacial lakes — risks, solutions

The flash floods in Uttarakhand underline the risk. One of India’s leading glaciologists discusses ways to assess and minimise this. Excerpts from an interview with D P Dobhal, a glaciologist, formerly associated with the Dehradun-based Wadia Institute of Himalayan Geology.

Written by Amitabh Sinha | Pune |
Updated: February 15, 2021 8:48:25 pm
Uttarakhand flash floods, snow avalanche, Himalayan glaciers, Glacial lakes, Glacial lakes risks, Uttarakhand news, Express ExplainedFlash flood in Dhauli Ganga rive in Uttarakhand on Sunday. (Photo: PTI)

Sunday’s flash floods in Uttarakhand underline the risk. One of India’s leading glaciologists discusses ways to assess and minimise this. Excerpts from an interview with D P Dobhal, a glaciologist, formerly associated with the Dehradun-based Wadia Institute of Himalayan Geology. He has worked extensively on Himalayan glaciers.

What could be behind the disaster in Uttarakhand?

It seems like an incident triggered by a snow avalanche. The area had seen two days of heavy snowfall last week. And suddenly the weather cleared and became a little warmer. That seems to have led to some melting of snow, triggering an avalanche, which resulted in a series of events leading to the flash floods.

But isn’t an avalanche unusual at this time of the year?

It is not. Such events happen in the higher ranges. They do not cause any damage in the remote areas. Actually, what happens in an event like this is that if there is a sudden change in temperature after snowfall, the fresh snow on the surface begins to melt and slip because of the higher ambient temperature. Also, most of the glaciers in the area contain large amounts of debris. When the snow begins to slip, it carries with it some of the debris. It ultimately becomes very strong, eroding everything that comes in the way.

The scientific teams would be reaching the spot soon, and we would get to know what happened. The real problem is in reaching there. These are inaccessible areas… Once they are there, it would not be very difficult to assess.

The Expert

D P Dobhal is a glaciologist, formerly associated with the Dehradun-based Wadia Institute of Himalayan Geology. He has worked extensively on Himalayan glaciers.

How big is the threat of such incidents continuing?

There are over 1,000 glaciers in Uttarakhand. Almost all of them are receding. Most of the glaciers also have debris cover. When glaciers retreat due to rising temperatures, the snow melts but the debris remains. This debris aids in the formation of lakes.

Over the years, the frequency of formation of these lakes has increased. But despite that, there are not many GLOF (glacial lake outburst flood) events happening in Uttarakhand. Not as many as in Sikkim, for example. The is because Uttarakhand has very steep slopes, and the water manages to find a way out.

glacial lakes, Uttarakhand flash flood, Himalayan region, Uttarakhand news, indian express news There are over 1,000 glaciers in Uttarakhand.

But there are over 1,200 big and small lakes in the high mountains of Uttarakhand. Many of them are increasing in size. A lot of them do pose a threat of similar kinds of incidents. It is extremely important to regularly monitor these lakes, and measure the rates at which they are increasing or shrinking. A threat assessment needs to be done and regularly updated, and this has to be incorporated into the planning process for all kinds of activities.

So why is this not happening?

I would not say the work is not happening. There are a lot more glaciologists and others who are working in the area, and generating data. The main problem is the lack of coordination and focus. There are glaciologists, geologists, hydrologists, mathematical modellers, remote sensing people, environmental scientists, and more. Multiple scientific groups and institutions are involved. But there is no coherent output. Lots of data are being generated but not being put to good use.

Even now, I guess there are eight to ten scientific teams on its way to the spot. Why do you need so many teams? One team with all relevant experts should be enough. All these groups will collect data, go back and write reports, and publish their findings. And all will be forgotten until the next disaster strikes us.

Uttarakhand flash floods, Ittarakhand death toll, Uttarakhand people missing, survivors, Uttarakhand tunnel, Uttarakhand news, Indian express news Rescue works underway near Raini village on Thursday.

I think we desperately need a nodal national agency that can coordinate all the research and also the operational things happening in this region.

What about the mission on Himalayan Ecosystem set up under the National Action Plan on Climate Change, and the plan to set up a National Centre for Himalayan Glaciology?

The plan for that centre was dropped. Someone in the government decided it was not required. I don’t understand how it could be not required. Even the separate centre functioning at the Wadia Institute of Himalayan Geology (in Dehradun) has been merged with the institute. The Himalayan Ecosystem mission does not get into the kind of activities that I am talking about.

There has to be one agency dedicated to the job. There are so many reports and data lying in the Ministry of Science and Technology, Ministry of Earth Sciences, Ministry of Environment and Forests, even ISRO and other places. Someone needs to put these reports together, create a database, and I think, within a year, we can start to focus on operational matters.

What are these operational matters?

It is not possible to completely prevent these kinds of incidents. But their potential to cause destruction can certainly be minimised. I will give you an example. The Lonar lake in Sikkim is one of the largest glacial lakes in the country. Recently, scientists have found a way to let the waters of this lake slowly drain at the nearby river at a regulated rate, so that there is no flooding, and the pressure on the lake does not become unbearable. Such solutions can be applied in Uttarakhand, and some work is being done.

But you cannot possibly go after applying these kind of solutions to each of the 1,000-plus lakes. A detailed study needs to be conducted to identify the ones that pose the maximum risk, monitor them continuously, and look for possible solutions that are suitable to local environments.

In fact, such an exercise needs to be done not just in Uttarakhand but in the entire Himalayan region.

Could large hydroelectric dams have contributed to Sunday’s disaster?

There are no storage dams being constructed in this area. The hydropower projects in this area are run-of-the-river type, and rightly so. It is not prudent to construct dams at such heights.

Again, it is a question of sustainable management. When a DPR (detailed project report) for any project is done, several studies are carried out — environmental assessment, river flow, pollution, forests. But glaciology is not part of these DPRs. I think this is a major flaw. Overall environmental assessment must also take into account the frequency of landslides and snow avalanches, the possibility of lake formation upstream, the ice volume in the glaciers, whether the glaciers are retreating or advancing, and the rate at which these changes are happening. I think these should be basic inputs. Ultimately, if a disaster strikes, it will impact not just the projects themselves, but also the people.

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