Impact of the Oct 2023 Teesta Valley GLOF on road communications - the continuing nightmare at Pedong and Toong

Map showing trouble spots at Pedong and Toong

Traffic bottle necks at PEDONG
Pedong (27.1594° N, 88.6157° E) is a small town in Kalimpong district and is nowhere near the Teesta valley yet the impact of the Oct 2023 GLOF is being felt daily by the residents of the town.
The Teesta valley GLOF reactivated a dormant landslide at Likhu Bhir which continues to pose a problem for traffic along NH10 so the Kalimpong District Administration has again closed that section of the highway for the weekend as per this travel advisory:

As a result the entire heavy vehicular traffic to / from Sikkim to the plains of North Bengal is routing thru Kalimpong and Pedong causing huge traffic jams in Pedong. The vehicles have also damaged water pipelines causing disruptions in water supply in the town and damaged other infrastructure since the roads are narrow and were never intended to handle such heavy, continuous traffic.

Traffic jam at Pedong

Likhu Bhir landslides on NH10 (Nov2023)

TOONG bridge
The bridge at Toong was vital for communications to North Sikkim and when the GLOF took it down, traffic had to be routed thru a longer and more dangerous route which we took while going to Chungthang in Nov2023.
The locals had constructed a wooden bridge over the Teesta river in Feb2024 (see below) which was being used by light vehicles.

Wooden bridge at Toong in Feb2024

However, the recent rains in the area resulted in the bridge being damaged (see video)

Since the alternate route is longer and much more cumbersome, locals at once got down to repairing the damage (see images of 06Apr2024 below)

I don't think this bridge will hold out for much longer now that the pre- monsoon showers have started over our region...which leaves us in a rather precarious position with regard to all the GLOF damaged road communications in our region - a question which I asked back in Nov2023...

                               How do we manage in the Monsoons of 2024?

My thanks to all friends and HA members from Pedong, North Sikkim who made this report possible. Please stay safe.

Praful Rao
Kalimpong district
Darjeeling Sikkim Himalaya
savethehills@gmail.com
9475033744

Impact of the Teesta Valley Glacial Lake Outburst Flood - Lachen (North Sikkim), the untold story

SaveTheHills (STH) and Junkeri Studio (JS) of Kalimpong have documented the Glacial Lake Outburst Flood (GLOF) disaster of 04Oct2023 extensively in this blog and while doing so we visited numerous places, maybe 20 or so in the Teesta Valley both in W Bengal and Sikkim.
On 17/18Nov2023 we were in Chungthang, North Sikkim where the GLOF destroyed the 1200MW Sikkim Urja dam and saw the humungous devastation there. We interviewed scores of people and photograph them and published the report in our blog – which has been well received all over.
Having gone that far, we were unable to visit Lachen, a small town 39 km north of Chungthang because the roads were totally destroyed by the GLOF. We did make an attempt but the road ceased to exist approximately 5 km north of Chungthang – the road continues to be non-operational even today.

On 17Feb2024 we were fortunate to meet Mr Dathup Lachenpa (DL) a person in the tourism business in Lachen; he had walked across to Chungthang from Lachen because there is still no motorable road.
He was in Kalimpong for brief while and we caught up with him to check how the GLOF impacted town of Lachen. Our interview with Mr Lachenpa:

STH/JS: Welcome, Dathup.
Firstly, can you tell us a bit about Lachen and what is the main source of livelihood there?
DL: The approximate population of Lachen is around 2000, the altitude of the town is approximately 9000’ and main source of livelihood is tourism but there are quite a few government contractors and employees as well.
STH/JS: Lachen was the first 'urban' centre which was hit by the GLOF from South Lhonak Glacier on 03Oct2023.Can you tell us whether you had any early warning regarding the floods since we know there was an Indo-Tibetan Border Police (ITBP) post further north who had issued alerts. Also approximately what time did the GLOF hit Lachen?
DL: I am not sure of the exact time when the GLOF hit us but it must have been around midnight – we were sleeping and heard this sound like a huge wind which woke us up. My home is a little above the town and when I went outside, there was no storm – the weather was quite clear and I could see stars in the sky. Since there was no storm but the loud noise persisted, I suspected something must be happening in the river and then I saw a lot of smoke rising there, that’s when I realized it maybe the river was overflowing or it was a landslide. I never expected the GLOF (from South Lhonak Lake) to be hitting us. I only realized in the morning that this was a major disaster when we went out towards the river and saw how much devastation was caused by the force of the river. At around 12.30am on 04Oct2023, the electricity and cell phone system went off. I expected a lot of damage by the impact but never on this scale of devastation.
STH/JS: How close is Lachen to the Teesta or more correctly Lachen Chu river? Is the town of Lachen on the banks of the river?
DL: Lachen town is located on higher ground, a little above the river.

Lachen town

STH/JS: Was there any destruction or damage to property or were there any fatalities in Lachen due to the GLOF?
DL: Yes, we ourselves lost a new home which we were constructing and I believe two labourers from Border Roads Organization (BRO)were swept away from the banks of the river at Zema.Zema is slightly north of Lachen towards the glacier.
STH/JS: And in all this you did not get any early warning whatsoever?
DL:As far as I know, we did not get any early warning.
STH/JS: Do you know if the government authorities or Phipon (Headman) received any early warning? - the ITBP post near the glacier sent some warnings, were they received at Lachen?
DL: The ITBP camp is located up there at Zanak 2, maybe they informed their people downstream but nobody informed us.
STH/JS: So what you are saying is that the casualties were limited and damage was less only because Lachen town is located at higher ground and the Lachen Chu or the Teesta river flows in a valley below.
DL: Yes
STH/JS: What is the damage to infrastructure and bridges around Lachen?
DL: There was a lot of damage. In Lachen, 4 bridges were washed away. 3 bridges connected Lachen to Chungthang and one connected us to Thangu.
STH/JS: Have these communication lines (bridges) been restored?
DL: Communication towards Thangu has been restored, with an army bailey bridge being constructed, so light vehicular traffic is now possible. This bridge is on the river bed and may not survive the monsoons so they are re-building the other one.
Three bridges towards Chungthang were washed away, so the route has been diverted and now there is only one bridge which has to be crossed at a place called Boonsoi, 10km south of Lachen. This RCC bridge at Boonsoi survived the flood.
STH/DL: We know that the BRO is working on the road from Chungthang northwards to Lachen. I believe the progress of this work is very slow and I also know people from Lachen are working on the road towards Chungthang.
DL: Yes, we (Lachen public) have succesfully completed one portion from Lachen towards Chunthang which was very difficult at a place called Taru. We encountered only solid rock there. The BRO helped us and we have managed to clear that section for vehicular traffic so the road upto Menchithang, a distance of approx 20km from Lachen is motorable. So now we have to walk 7-8kms after which we reach another motorable section towards Chungthang.
In this regard, the Lachenpas made three wooden bridges.

Local people together with BRO personnel carving out a new road from Lachen to Chunthang

The Lachenpa community constructing a wooden bridge across the Teesta river (also called Lachen Chu) at Zema to connect Lachen with Thangu. Notice the large landslide in the background

STH/JS: We know that Lachen was marooned for some time after the GLOF, can you tell us how many days you were totally cut off and how did people in Lachen survive?
DL: At that time almost 70% of the people were in Thangu, harvesting potatoes and radish and the rest were in Lachen. We habitually stock rations and that's how we survived - on stored rations.
STH/JS: Did the army or air force also help in ration supply?
DL: No, but they certainly helped with the evacuation - the relief material came from local people of Sikkim.
STH/JS: Were there any tourists in Lachen at that time and how were they evacuated?
DL: Yes we had around 500 tourists who were stranded in Lachen at that time; they were evacuated by AF choppers from Chatten (army base near Lachen).
STH/JS: What was the impact of the disaster on livelihoods of people?
DL: The impact is huge because we lost a lot of revenue in tourism – Oct to Dec is a big tourist season for us and we have lost these 3 months and we are not certain in 2024 as well, because road access to our area is still not possible.
STH/JS: Fortunately, it did not snow heavily in North Sikkim during this winter and as such you did not have much problems with ice-bound roads etc. How concerned are you about the forthcoming monsoons with the road condition being what it is? How will you manage your supplies?
DL: Getting supplies through thru Dongkha La pass (which is at 18,000’) would be impossible but what people do is that during the annual puja time in winters they buy a lot of rations from monks and stock up – also people in Lachen were stocking up dry rations like oil and rice from Menchithang etc thru porters who would carry the stuff. However, we would have a problem with LPG cylinders (even though we have fire wood) because people largely use gas for cooking these days.
STH/JS: What about health care issues in Lachen after the GLOF?
DL: Yes, this is a major concern. Recently a 27yr old man from Lachen died in a hospital in Siliguri because he had to be evacuated through Dongkha La pass (18,000’) when he was ill; this is a huge challenge for a sick person. So right now, we are most scared of falling sick in Lachen and hope that no one becomes unwell because we only have a primary health centre which does not have many facilities and presently, I don’t think we have a doctor there.
STH/JS: So what happens to the sick and elderly people at Lachen?
DL: (Chuckles) – We just pray that no one falls ill.
STH/JS: What about children’s education?
DL: They were at home during the winter holidays and have now returned to school – some of them went by car through Dongkha La pass others walked back to Chungthang etc – most of them, walked back I think, because they were scared of heights at Dongkha La.
STH/JS: The hikers trail for walking back (between Lachen and Chungthang) seems very precarious
DL: Yes, the footpath for walking is quite dangerous, if one slips there is no chance of survival – at many places the path is not more than a foot wide.

Makeshift wooden ladder which is used while walking from Lachen to Chungthang

Narrow and dangerous footpath which is being used by people who walk from / to Lachen today.

STH/JS: So how long do you from a layman’s perspective, expect the Chungthang – Lachen road to be restored?
DL: Our Chief Minister had promised that after rebuilding the bridge in Chungthang town, all the resources (machinery and manpower) would be diverted to the Lachen road. That has not happened. Yes, machines are there but not the type which is required to cut rock and so on. We were hoping that road communication would be restored within 2-3months but it has been 4 months and progress is very slow. With no heavy earth moving machinery at site, people are saying it may even take a year for the road to be restored.
STH/JS: Immediately after the disaster, were there any homeless people or was there any requirement for relief and shelter?
DL: Some areas and parts of roads especially in the bazar (town) were cracked and people were reluctant to live there, because of rumors and continuous landslides. So people shifted to relative's home at higher grounds near the monastery. However, there were no homes which were destroyed in Lachen.
Relief supplies as far as I can remember, came in after a week or so. I think this was contributions from locals in and around Sikkim and it was flown in by choppers.
STH/JS: Can you tell us more about the Chungthang-Lachen road status again?
DL: Before the GLOF, the Chungthang-Lachen trip used to take 1 hour by vehicle. Now we can travel by vehicle from both Lachen and Chungthang but the midsection is still not motorable and we have to walk that stretch and it takes us around 2hrs. The vehicles used are all SUVs with 4 wheel drive.

Impact on road communications by the GLOF: Lachen-Chungthang road at Menchithang

                                       Landslides along the Lachen Chu (river) valley

STH/JS: You mentioned visiting the Lachen Chu river a number of times after 04Oct2023 – can you describe the scene? Were there any landslides? And how did people from Lachen spend the next few days after the GLOF?
DL: The power supply and mobile networks went dead from 04Oct2023 – people were scared and moved here and there, trying to find out what was happening. We noticed the river was still swelling up and there were lots of landslides taking place in and around. When we went to Zema where there was a bridge which connected Lachen to Thangu, we found that the landscape had changed totally, we could not recognize where the bridge was. The whole day the river was flowing at the same high level.
Two days or so later when we went towards Zema again , we found a huge increase in landslide activity all along the road.
STH/JS: We are aware that a Swiss and Govt of India team had gone upto South Lhonak Glacier (in 2023) – did they go through Lachen?
DL: We heard about that too but I do not know the details. People were in fact blaming them for what happened – and believe that they may have done something. We believe our lakes are sacred and do pujas and visit monasteries while visiting these (holy) places.
STH/JS: Which is the nearest lake from Lachen?
DL: By road, it is Gurudongma lake
STH/JS: How much time would it take to reach South Lhonak lake from Lachen?
DL: Now there is a motorable road to Zanak 2 where they have the last ITBP camp and that takes around 6hrs from Lachen. Beyond that I have no idea.
STH/JS: Do you know whether (the ITBP camp at) Zanak 2 was affected by the GLOF?
DL: I think so, I think I saw some photographs.
STH/JS: Have people returned to Lachen from Thangu?
DL: Yes, its wintertime and its not possible to stay in Thangu. Everyone has returned but some are in Gangtok and others in Siliguri etc and children have returned to school.
STH/JS: What is the approximate economic loss which took place due to the GLOF say in terms of loss of farmland,destruction of orchards etc
DL: I can say we have lost a lot of land – pasture land for example. Our dairy animals go to lower altitudes during winters, to places like Denga which was a little above Chungthang. These areas have been washed away by the GLOF. People are now living on the roadside at Rabong and so on. Further, I think in terms of loss, all of Sikkim has been impacted - shops, hotels and so on . I am sure the loss is huge and in many crores.

                              Destruction of farm and grazing land at Menchithang.

                                               Landslides along the valley at Zema

STH/JS: Do you know of any loss to Govt departments including the army?
DL: Fisheries department have lost some trout farms, animal husbandry department have lost their angora farm, Tibetan sheep have lost their grazing land and so on.

                                    Destruction at army camp at Menchithang

STH/JS: What sort of help have you received from the administration?
DL: It has been four months since the GLOF and we still have not seen the District Magistrate (DM) on site or anywhere. We met the ADC (Additional District Collector) who came to Lachen after 7-8 days, maybe he was representing the DM – we don’t know.
With the help of the Government, the electricity was restored after 8-9days, most probably because we have a new power station in Lachen, which was not affected by the disaster. Our cell phones (only BSNL network) started working after a month or so but the performance was poor, with a lot of disturbances
STH/JS: You mean you had no communication for a month?
DL: No, I think the ADC had come with a satellite phone but I am not sure how many could make calls. We also could use the army lines but that too was difficult because of the long queues of people waiting.
STH/JS: How do you see the next few months with the monsoons coming up?
DL: We are really scared of the monsoons and the heavy rain it will bring. It will affect us a lot and people are thinking of stocking supplies before the rains and we will avoid traveling during that time because of the road conditions.
STH/JS: Can you tell us the cost of travel from Lachen to Chungthang via the Dongkha La pass?
DL: I heard the freight charges of utility (short body) truck bringing supplies from Mangan to Lachen via Dongkha La is Rs 25,000/-
STH/JS: Thank you so much for your time, Mr Dathup Lachenpa and for sharing this information about what happened in Lachen. It will certainly be most useful for people studying the October 2023 GLOF disaster in the Teesta Valley.

Photo credits: Dathup Lachenpa

Praful Rao
Kalimpong district
Darjeeling - Sikkim Himalaya
savethehills@gmail.com
9475033744
with
Praveen Chhetri
Junkeri Studios
Kalimpong
himalayagallery@gmail.com
9733185815

Impact of the Teesta Valley Glacial Lake Outburst Flood (GLOF) - updates from North Sikkim (Feb2024)

As has been reported by us in this blog, the GLOF disaster of Oct2023 devastated large parts of the Teesta valley both in Sikkim and W Bengal. Placed below are some recent updates from North Sikkim:
Naga area of Mangan district
The devastation in Naga and Toong area of Mangan district has been covered here.
Recent (09Feb2024) closeup photos of landslide affected areas of Naga are shown below:

A telephoto image of the same area which I took from the opposite hill on 18Nov2023 (below) reveals hardly any change in the intervening 3 months.

As per my source in Chungthang, people from these homes have evacuated and are living with relatives or at rented places.
Toong bridge and road status
The GLOF of 04Oct2023 destroyed the bridge over the Teesta river at Toong (see photo of 18Nov2023 below). This bridge connected Mangan (dist HQ of North Sikkim) with Chungthang

A 'log' bridge (below) built in this area has temporarily restored this communication route.

However, for the time being the bridge is closed between 10.00am to 4pm to allow road repairs as such commercial vehicles and others still have to route via a long route via Saffo- Shipgyer - this route not only takes double the time but is narrow and dangerous at places.

As per information received, the progress of repair of Chungthang - Mangan road and also the Chungthang - Lachen road is slow and this is worrisome since the pre-monsoon season accompanied by intense thundershowers are due to start in March 2024.
Here are some rough stats:
a. The freight charges for a truck with 10 tonnes of load from Siliguri to Chungthang was approximately Rs22,000/- (incl of taxes), when the main roads were available.
b. Now, since the main roads are not available, the detours have pushed up the freight charges to Rs 31,000/- and also the trucks can only carry 8-9 tonnes of material on the alternate route.
c. So because the freight charges have increased while the load which is being carried has decreased - a single brick in Chungthang now costs Rs18.
Chungthang town
Among all the urban centers impacted, the GLOF dealt it's severest blow to Chungthang town at around 12.35am on 04Oct2023. We have covered it in detail here
Even when we visited the town on 18Nov2023, more than a month after the devastation, the whole place still looked like a war zone but I am glad to know that the people of Chungthang are slowly getting back on their feet again. Placed below are recent images of Chungthang town where the almost 10 feet of sludge mud and sand which buried the streets, homes and buildings have been cleared off and shops are open and life is slowly getting back to normal.

Praful Rao
Kalimpong district
Darjeeling- Sikkim Himalaya
savethehills@gmail.com
9475033744

AFTER THE FLOOD - By Pemzang Tenzin (Mangan, North Sikkim)

 

Zanak, at the base of the aptly named Sentinel Peak, is the last outpost on the lesser used but religiously and historically important Chorten Nyima La route to Tibet.  The ITBP personnel stationed there first raised the alarm on the South Lhonak Glacial Lake Outburst Flood (GLOF) and possibly saved the lives of many people in the path of the ravaging flood.

 South Lhonak Lake, like many other glacial lakes, is meltwater stored behind a fragile dam created by debris and ice left behind by the snout of the retreating glacier.   The 1950 Swiss Foundation map of Sikkim, based on earlier Government of India surveys and still used today by trekkers and mountaineers, does not show a lake at this location.  The lake has grown from nothing to its present dimensions of more than 200 standard football pitches within a span of less than a hundred years.  The glacier is expected to recede further and the size of the lake will increase in the very near future. The volume of water stored is thirteen times the storage of the erstwhile Teesta Urja reservoir.  It is estimated that half this volume spilled out during the October GLOF event.

This is a story repeated again and again in others parts of the high mountains as the ice cap starts melting at an accelerating rate due to the effects of climate warming.  The Eastern Nepal, Sikkim and Bhutan regions are considered a hotspot for GLOF activities.  In Sikkim, the total area covered by ice caps is larger than the size of some of the districts.  The Swiss Consortium, in partnership with National Disaster Management Authority (NDMA) is studying some of these lakes.  They have compiled a list of twenty five lakes in Sikkim that have been red-flagged by different agencies as being potentially dangerous.  Twenty four of these are located in North Sikkim, almost equally distributed along the Lachen and Lachung axes and one in West Sikkim.  With increased melting and the recession of glaciers, more lakes are expected to form or increase in size, making new areas in other areas of Sikkim vulnerable to GLOF.

Sikkim’s limited experience with mitigation measures for dangerous lakes, like siphoning of the same South Lhonak in 2016 and controlled breaching of Mantam in 2017, has met with at best limited success. The NDMA-Swiss Consortium project involves studying the South Lhonak Lake and the Shako Cho as exemplars to suggest mitigation measures or to design an Early Warning System.  Without ground access, the Swiss experts had already completed the desktop studies based on satellite imagery.  Due to security reasons, the team could only make its first field visit in September of 2023 but before the team could even take stock of their visit, South Lhonak Lake surprisingly burst on October 3rd.

 It is difficult to create an accurate time line for the GLOF event and the arrival/peak flows at different towns as both public and official reports vary considerably.  This is due to the fact that the flood happened in the middle of the night and it builds up gradually from first arrival to peak flood levels over  a matter of hours.  The ITBP camp noticed the level rise in the Goma Chu, the effluent stream from South Lhonak at about 10.30 at night (the Print), though the triggering landslides and the breaching of the lake must have happened at least hours earlier.  In India, Central Water Commission (CWC) monitors flows, including GLOF, in all the significant rivers through a network of instrumentation.  Hydrologist/activist Himanshu Thakkar writes in his blog that the automatic stations upstream of Dikchu, including Lachen stopped reporting sometime before 10.30 pm on October 3rd and, in his opinion, these stations were probably non functional.  Downstream of Dikchu, instrumentation show the river rose by about the height of a three storey building at Khanitar (near Manipal) and by about a five storey building at Melli where the CWC stations are located.  At these locations, the floods first arrived at around midnight but took a couple of hours to build up to maximum flows. 

 The actual levels recorded at Khanitar were more than twice as high as predicted in  the CWC simulation for South Lhonak GLOF published in their advisory in 2016.  Gazoldoba near Siliguri, located a couple of hundred kilometres downstream of the GLOF source, recorded high flows (more than 7000 cumecs above pre flood flow) despite the flood flowing through a number of manmade and natural impedances on its long journey downstream.  The flood marks recorded at RangRang also augments this observation that the flows on October 3rd/4th were much higher than those simulated both by CWC and the Swiss consortium.  The flood marks upstream and downstream of Chungthang could also provide an estimate of the effect of the collapse of the dam on flood flows.

 The dam failure at Chungthang has highlighted the vulnerability of power projects and the inadequacy of the existing safety protocols in the face of abnormally high flood flows associated with GLOFs.  The dams are not designed for overtopping and the amount of water it can manage are conventionally calculated from hypothetical rainfalls in the catchment area.  While repairing and rebuilding the damaged or collapsed dams, GLOF has to be factored in.   There is a need to have a relook at the hydrological design and flood response protocols of all existing dams in Sikkim and elsewhere in the Himalayas.  It is reasonable to question whether the reservoirs were operating at minimum levels in October (monsoon period) as required by safety protocols and whether the gates were working properly.  There is a need for more oversight from dam safety committees in the state (if it exists) and the centre at both the design stage and during operations.

 Chungthang is built on a triangular river terrace at the confluence of the Lachen and Lachung rivers.  River terraces are ephemeral geographical features which seem doubly vulnerable to both GLOF and the shaking of earthquakes.  The October 3rd/4th GLOF seems to have severely damaged or wiped out most of the river terraces upstream of Dikchu along with infrastructure and property built on them.  Parts of Toong and Rel villages built on Talus slopes on the Teesta a few kilometres downstream of Chungthang are collapsing due to undercutting by the flood.  Here, the houses on and below the highway have toppled while those above the highway have also developed cracks and may not survive the next monsoon.  Reports of cracks in structures in other areas situated on hill slopes above the banks of the marauding flood also needs to be investigated empathically.

 Whether it is landslides, GLOF or any other natural disaster, the best mitigation measure is avoidance of the vulnerable area.  Past experience shows that once the disaster is temporarily abated, people double down and start rebuilding in the vulnerable areas.  Due to ad hoc decision making and paucity of funds, Government departments usually put promises of resettlement in the back burner with the passage of time and slowly forget about it.  With our increasing populations and increased exposure to multiple hazards, there is a need to legally prevent development and houses in the designated disaster prone zones and to formulate comprehensive and humane disaster rehabilitation policies. 

 Beyond activism and partisan politics, we need to rationally study and understand these constantly evolving and growing natural threats to our society and learn to cope with them.

Pemzang Tenzing
21Jan2024
Mangan
pemzang@hotmail.com

Photographic record of the impact of 04Oct2023 GLOF at Chungthang (North Sikkim) and its vicinity.

Chungthang (Lat 27 36 13.3 N Long 88 38 43.5 E, Elevation:1612.5m) is a small town (population around 4000) in North Sikkim located at the confluence of Lachen Chu ('Chu' means 'Water' in Tibetan) and Lachung Chu. It was also where the Sikkim Urja (Teesta III) dam, a 1200MW, 60 M high Concrete Faced Rockfill Dam (CFRD) was built - it was commissioned in Feb 2017. The dam was the largest run of the river project in the region and the power house was located downstream at Singhik village.
Sikkim Power Investment Corporation Limited (SPICL), a 100% wholly owned public limited company of Government of Sikkim, is the holding company of the project.
The growth of Chungthang between 2006 and 2020 is shown below:

In this regard, quoting from The Sikkim Tourism Development Corporation (STDC) website: 'With the recent hydropower development in the area, the landscape of Chungthang is changing rapidly and is becoming a major settlement in North Sikkim.'
The glacial lake outburst flood (GLOF) from South Lhonak glacier in the late hours of 03Oct2023, released a massive volume of water along Lachen Chu which deluged and engulfed almost the whole of Chungthang at around 12.30am on 04Oct2023. It took down the double lane concrete bridge at Chungthang after sweeping away at least 3 bridges towards Lachen and one bridge across the Lachung Chu.
Amidst the rain, roar and rumble of the river and pitch dark conditions no one is precisely sure when the Teesta III dam collapsed but it did so sometime during the night. It was only on the next day that everyone in Chungthang became aware of the horror and scale of devastation.
The GLOF and the dam collapse caused an unprecedented disaster all along Teesta river valley which SaveTheHills has been documenting since 04Oct2023.
We were in Chungthang for the entire day on 18Nov2023 and talked to many affected people while photographing the disaster - besides just being awed at the raw and vicious power of nature.

What remains of Sikkim Urja (Teesta III), 1200MW dam

Drone image from Chungthang town looking down stream. The magnitude of nature's forces involved is evident from the giant boulder which has been hoisted to that height and parked in a slot.

Drone image of the dam looking upstream; Chungthang town is in the distant with Lachen Chu on the left and Lachung Chu on the right. The extent of damage is visible even from far.

Satellite image of the dam

This was where Sikkim Urja (Teesta III) dam had its entire office setup. The GM's office and other residential quarters were also here. The surging waters swept away all and left behind some trash and gigantic boulders.

Gigantic rock formations have emerged after the GLOF gouged out all the earth on top (which now form the sand and sludge deposits downstream). The massive boulder clogging up a dam structure can be seen in the background.

Parts and machinery from the Stage III dam now litter the river bed at Chungthang.

The 'GLOF Only' areas. 

By this we mean, areas upstream along Lachen Chu river where the dam burst did not have any impact and the destruction was caused solely by the GLOF from South Lhonak lake.

It was surprising (and scary) to see the amount of damage which had been caused by the GLOF alone. In the distant one can see the ITBP colony where the road to Lachen seen on the right ends.

The damage caused by only the GLOF from South Lhonak lake is huge as can be seen.This drone image reveals the scouring of the river bed caused by the violent waters just a few kilometers towards Lachen from Chungthang.

The impact on Lachen Chu river bed by the GLOF approx 2 km north of Chungthang is seen here. The road to Lachen is only upto the ITBP colony seen in the distant.

Close up of the damage caused by the GLOF alone. A bridge to Lachen has been torn down here (27 36 47.4 N 88 37 47.2 E), further north 2 more bridges have been destroyed by the GLOF, numerous power pylons and towers have been damaged. Army personnel in areas around Lachen reported strong vibrations during the event.

This is where the road to Lachen ends (27 36 42.7 N  88 37 51.4 E) Elev 1705m (Drone image).

Impact on Government assets

Sikkim Government assets located towards the southern tip of Chungthang town were severely damaged by the GLOF

The Legal cell building at Chungthang on 18Nov2023

The SIB office at Chungthang.

The shredded Police Station (Thana) at Chungthang is on the right. A huge truck has been neatly shoved into an office in the thana by the GLOF as if someone had parked it inside. The Chunthang Fire department building, Sikkim Tourism Department guest house has also been extensively damaged in this area.

ITBP shacks along the Lachung Chu which were buried by the backflow from the GLOF. This river was otherwise not affected by the event. Notice this river has turned green as it is winters now - surprisingly, the Lachen Chu is still loaded with silt and brownish. A bridge further up was destroyed by the backflow.

The Chungthang playground and stadium which were deluged by the GLOF.
The army lost a lot of assets  in this area - fortunately no life was lost.

A rifle rack from the Sikkim Police Station (Thana) with the weapons swept away by the swirling waters, at the dam site.
This, along with the loss of army assets adds another dimension to the safety of our riverine areas and even dams.

Chungthang town

The GLOF of 04Oct2023, left the tiny town of Chungthang on its death throes. The midnight floods affected almost every part of the town and the only sounds audible, when we visited Chungthang on 18Nov2023, were the grinding and clanking of heavy machinery as the residents tried to excavate their homes and get their lives back together.
More than 54 RCC buildings and homes were damaged by the floods, many smaller wooden homes and shacks were simply swept away. Also what was lost were countless Buddhist artifacts, monuments and antiques which every affected home had and which the floods snatched away.
A school was destroyed in the centre of town.

Drone image of Chungthang town on 18Nov2023, showing the extent of damage by the GLOF.

Satellite image of the above area.
On the left, Lachen Chu or the Teesta river flows downstream and a Bailey bridge has been  constructed by the army engineers on 16Nov2023 at 'A' above which allows some sort normalcy of movement and supplies coming into the town.

Drone image showing the devastation wrought by the GLOF in areas adjacent to the river bank.

Drone image from the road to Lachen showing erosion of the river bank adjacent to Chungthang town. In the foreground are areas where there were several army installations.

Satellite image of the playground area of Chungthang town.

The town on 18Nov2023. Massive rocks are strewn all over and 10-15 feet of sludge plasters much of the town area.

An army truck has been parked inside a room by the GLOF. Notice the level to which the flood waters reached.

Chungthang on 18Nov2023.
The gilded dome of Gurudwara Nanak Lama Sahib is seen in the background.
The Gurudwara and its staff provided and continues to provide extraordinary service to the denizens of Chungthang. The ground floor of the Gurudwara was inundated by the GLOF and the staff evacuated temporarily to return quickly and provide food and shelter to thousands of people. While we were in Chungthang, 70 odd homeless people were staying in the complex and everyday 3 - 4000 meals were being provided to anyone who wanted food.

Photo of 05Oct2023 showing removal of sludge and debris in front of the Gurudwara at Chunthang (Photo credit: Lhendup Lepcha)

Officials of the Sikkim Government conducting a survey on losses to homes and property at Chungthang. They said government engineers were also testing the structural stability of damaged buildings. With much of the town in ruins, this process will take some time to complete.

The Rivers and the Environment

Photo of 05Oct2023 shows a gap where there was a double lane concrete bridge over the Teesta at Chungthang. It was taken down by the GLOF. (Photo credit: Lhendup Lepcha).

A tiny bamboo bridge over the Teesta for ferrying men and material before the current Bailey bridge (below) was completed by army engineers.

Photo of 18Nov2023 shows a bridge across the same spot, which army engineers put across the Teesta on 16Nov2023..
The armed forces have always taken a lead role in helping out in all disasters and so it was in Chungthang in Oct2023 where they were instrumental in providing warning, evacuating tourists and saving lives and the civilians in Chungthang I talked to gratefully acknowledged this.

Photo of 07Oct2023 showing army/BRO/ITBP/ and other people trying to put a ropeway across the Teesta at Chungthang.The river was again in spate and there was light rain as such the effort was abandoned.(Photo credit: Lhendup Lepcha)

Heavy road construction machines and men of the BRO working on the road towards Lachen.
(Photo credit: Lhendup Lepcha)

The completion of repair of the Chungthang - Lachen road may take anywhere from 3 - 6 months and right now Lachen is connected to Zema and Thangu only by a temporary bridge. The people of these areas will require extensive help to face the harsh winters ahead.

All in all, I am amazed at the scale and ferocity of nature's revenge.

My humble thanks to all who helped.

Praful Rao
Kalimpong district
Darjeeling-Sikkim Himalaya
savethehills@gmail.com
9475033744

with

Praveen Chhetri
Junkeri Studios,
Kalimpong
junkeristudio@gmail.com
9733185815