Updated satellite images of Oct 2023 GLOF affected areas from Google Earth

Google Earth has recently (Jan2025) made available high resolution images of some areas of North Sikkim which reveal the devastating impact of the Glacial Lake Outburst Flood (GLOF) of Oct2023 in North Sikkim. The images below juxtapose the affected areas with historical snapshots, illustrating the catastrophic consequences of the GLOF.

Chungthang town / confluence of the Lachen and Lachung Chu

Chungthang (elevation 1790m/5870', 27.62°N 88.63°E), a town in North Sikkim, is situated at the confluence of the Lachen Chu and Lachung Chu rivers, which merge to form the Teesta river.
On October 3, 2023, an avalanche triggered a GLOF in South Lhonak glacial lake (elevation 5200m/17000'), approximately 75km upstream from Chungthang along the Lachen Chu. The resulting sudden release of around 50 million cubic meters of water made it the largest GLOF in the Himalayas in recent history.
For a detailed account of this event, refer to this publication in Science magazine
STH has closely documented the Teesta valley GLOF of Oct2023 in this blog from the date of occurrence.
Satellite images along with photos of the affected areas are placed below:-

Chungthang town (close up)

Chungthang town (Dec2024)
The still devastated playground and army camp area is seen at the center with the gilded dome of the Gurudwara towards the right side.

Chungthang town playground on 19Nov2023 when we visited the area.

The 1200mw Sikkim - Urja dam and bridge at Chungthang

This was the largest dam in Sikkim and was located downstream of the confluence of the Lachen and Lachung Chu rivers. The 60m rockfill, run of the river dam was commissioned in Feb 20217 at a cost of Rs 14,000crores. Along with the dam, a major bridge (centre top of photo) connecting Chungthang to the rest of Sikkim was also destroyed by the GLOF.

The remnants of Sikkim Urja dam which collapsed in the GLOF on 04Oct2023. Photographed on 18Nov2023, when we visited Chungthang.

A double laned concrete bridge connecting Chungthang to the rest of Sikkim was destroyed by the GLOF here on 04Oct2023

Munshithang (27.6324° N 88.6157° E)

Munshithang, an ammo depot for the Indian army was totally destroyed by the 04Oct Teesta Valley GLOF. On receiving warning of the rising waters in the Lachen Chu, 92 personnel of the ammo depot moved to  higher ground and thus their lives were saved. However, it was 4 days before they could be evacuated - due to bad weather which prevented helicopter flights.
Nothing could be retrieved of the ammunition and equipment lost to the GLOF.

Toong bridge over the Teesta river  (27°33'0.15"N 88°38'35.17"E)

We visited this area on 19Nov2023 and photographed the bridge and the Toong checkpost both of which were destroyed by the GLOF (below)

There was only a small bamboo bridge across the Teesta for pedestrians to cross the river on foot in Nov2023

The Toong police checkpost had been vacated and dangled precariously from the edge of the road

Another view of the vacated police checkpost in Nov2023

Faced with the sheer necessity of communicating, the local community start constructing a wooden bridge across the Teesta at Toong.

 Naga Gram Panchayat (Mangan district, North Sikkim)

Naga GP is located approx 14km from Mangan (district HQ of N Sikkim district) towards Toong and was one of the worst affected areas when we visited Chungthang on 19Nov2023.

It continues to be a wrecked and desolate place as can be seen from the recent photos (of Dec2024) below (photo credits: Rinchen Lama, IIHS ,Bangalore)

Google Earth has unfortunately not updated satellite images of areas south of Naga area (North Sikkim) which are still of 2022 vintage as such they do not show the impact of the GLOF in these areas.

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

The Oct 2023 Teesta Valley GLOF disaster gets its due recognition: An article published on the disaster in SCIENCE MAGAZINE

The GLOF sweeping past the Teesta bazar (W Bengal) on 04Oct2023. This drone photo by Praveen is certainly one of the most iconic images of a GLOF.

The SCIENCE MAGAZINE (https://www.science.org) is widely recognized as the world's most prestigious journal on science, publishing the very best in research across the sciences, with articles that consistently rank among the most cited in the world. It is published by the American Association for the Advancement of Science (AAAS), the world’s oldest and largest general science organization.
Dr Ashim Sattar (IIT Bhubaneshwer) is a glaciologist who has done a huge amount of research on the South Lhonak glacial lake and had almost predicted accurately the GLOF which occurred on 03/04Oct2023. I have quoted extensively from his write up earlier in this blog and had the good fortune of meeting him at Chitrey, in the Teesta valley last year when he was enroute to Gangtok, Sikkim.

With Ashim (left) on 21Feb2024 at Chitrey

In our brief interaction, he mentioned he was working with many world experts on a paper on the 03/04Oct2023 Teesta Valley GLOF disaster which I daresay was all but ignored by government and the media even  though it was the largest GLOF disaster in the Himalayas in the recent past.
Since then I have personally had many interactions with him, shared photographs of the GLOF and affected areas and discussed the impact at the many places we had visited while recording the GLOF.
Even though I am unaware of the technical details of the mammoth work that Ashim and all the associated scientists have put in, I know getting it published in Science Magazine was another huge challenge and it took months of meticulous work by Ashim with literally many emails being exchanged between all of us.
The full article published by SCIENCE MAGAZINE yesterday, is here (https://www.science.org/doi/10.1126/science.ads2659)
In addition, Dr Dave Petley, VC Univeristy of Hull (UK) who is one of the co - authors has published his synopsis of the whole article - which is here (https://eos.org/thelandslideblog/sikkim-glof-october-2023)
My grateful thanks to Dr Ashim Sattar and all the eminent scientists who devoted so much time and effort towards this article.

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

A post GLOF look at parts of Teesta Valley (Part - 2)

More than a year has passed since the devastating GLOF disaster of October 4, 2023, that swept through the Teesta Valley. We have extensively documented the catastrophe and its aftermath in this blog. Following the GLOF, the 2024 monsoon season brought further destruction, exacerbating the damage to already weakened structures, roads, and the environment.

In the photos below, we aim to capture the changes that have unfolded during this time. With another monsoon fast approaching, our repeated calls for mitigation efforts during this dry, non-monsoon period have largely gone unheeded except for the transfer of maintenance of sections of NH10 in West Bengal from the state PWD to NHIDCL, a step forward, which is widely regarded as too little, too late.

Sikkim

Sangakalang

Both these bridges on the river bed and a larger bridge which spanned the river were swept away during the monsoons of 2024.

Dzongu

Fidang

Dikchu town

NHPC Stage V dam (Dikchu)

Sikkim and West Bengal

Tar khola NHPC Power house

All drone images by Praveen Chhetri, Junkeri Studios, 9733185815

Praful Rao,
SaveTheHills
savethehills@gmail.com
9475033744

A post GLOF look at the Teesta bazar and its vicinity (Part -1)

A few days ago, a friend called from Mangan, the headquarters of North Sikkim district, eager to witness the aftermath of the Teesta Valley Glacial Lake Outburst Flood (GLOF) that occurred on October 4, 2023. She expressed difficulty in identifying the affected areas. I empathized, recalling how we began documenting the disaster through photographs and recordings on the very day it happened.

Over a year has passed, including a full monsoon season. During this time, nature has altered the landscape, roads and homes have been repaired, and damaged machinery and assets have been removed or replaced. These changes underscore the importance of promptly documenting disasters, at least through photography, to capture the immediate impact before recovery efforts and natural processes transform the scene.

The Glacial Lake Outburst Flood (GLOF) on October 4, 2023, caused the Teesta River's level to surge by approximately 3 to 4 meters throughout the valley. This event deposited substantial silt and debris along the river's course. While monsoon floods have since washed away some of these deposits, the river is gradually reestablishing its natural channel—a process that can span several years. Consequently, we must brace for potential challenges during upcoming monsoon seasons. The current dry season offers an ideal window for implementing necessary preparations; however, I have observed a concerning lack of such proactive measures and towards this end we have voiced our concern by writing to the highest levels in the country.

With regard to the disaster, I made a visit on 18Dec2024 to the Teesta bazar and its vicinity to check and photograph the area. My report:

a. River Condition:
The Teesta River has shed much of the silt and debris left by the October 2023 GLOF and is regaining its characteristic emerald-green winter hue. In some areas, the river has carved out a defined channel, reducing its erratic flow over the 3-4 meter thick debris layer deposited during the disaster.

b. Disaster Mitigation Efforts:
No visible disaster mitigation efforts were underway in Teesta Bazar or its surrounding areas. Residents I spoke to expressed deep frustration over the lack of action.

c. Local Economy - Rafting Resumes:
Rafting activities have resumed in the Teesta/Labar Boatay area, providing direct and indirect employment to approximately 2,000 people.

d. Tribeni Covid Hospital:
A footpath to the Tribeni Covid Hospital is functional. However, much of the hospital's infrastructure has been either looted or washed away by the floods, leaving it in a dire state.

e. NH10 Road Conditions:
On the short stretch of NH10 I traveled, significant repair work was underway near Likhu Bhir. However, areas around the 29th mile and Melli remain vulnerable, with visible cracks and sinking sections near the riverbank. These areas are at serious risk of collapse during the next heavy rains.
Placed below are images of the area:

Documentation of parts of the above report was supported by Royal Enfield, as part of their Social Mission Initiative


Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

ALL ABOUT CYCLONES: How cyclone track forecasts can change dramatically and how climate change maybe impacting them.

 We have been tracking the storm in the Bay of Bengal for several days now (as we normally do) and have been posting updates in our WhatsApp Group 'Hazard Alerts'.
On 26Nov2024, the forecast from IMD clearly said that the storm would intensify into a CYCLONE

This was changed and on 28Nov and the storm was expected to remain a 'DEEP DEPRESSION' and make landfall on 30Nov2024 as a 'WELL MARKED LOW' (see below)

The forecast was revised the next day and the track showed the storm intensifying into CYCLONE 'FENGAL'on 29Nov2024.
The latest forecast track from IMD of 'FENGAL' together with WARNING no '3' from JTWC is reproduced below.

The tracks from IMD and JTWC seem to coincide.
I am also posting an article from today's Statesman on how climate change maybe impacting cyclones in the Bay of Bengal

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744