Extreme rainfall event in Kalimpong district: 04/05Oct2025 ('Impact on Teesta Bazar')

The first photographic records of major flooding at Teesta Bazar is of the October 1968 disaster when extensive portions of the settlement were washed away by the Teesta River. The event also led to the collapse of the Andersen Bridge — a key river crossing at Teesta Bazar — reportedly as a result of the sudden failure of a landslide-dammed lake located further upstream.
Subsequent decades saw recurring flood impacts in the area. In October 2023, Teesta Bazar was severely affected by a Glacial Lake Outburst Flood (GLOF) originating from the upper Teesta basin. This event caused extensive damage along the Teesta valley and was documented in detail by SaveTheHills (STH).
In July 2024, the locality again experienced significant flooding. Despite detailed recommendations submitted by STH regarding necessary mitigation and risk-reduction measures following the 2023 event, most corrective actions remained unimplemented. Consequently, the warning issued in the 2024 report — “Failure to take timely corrective action will mean a repetition of this whole scenario once again in 2025” — was validated when a similar flood event reoccurred in October 2025.
This pattern underscores the urgent need for comprehensive and coordinated flood mitigation interventions at Teesta Bazar, including structural and non-structural measures, to prevent further recurrence of such disasters in the future.
As expected the town again experienced major floods during the deluge of 04/05/Oct2025. STH photographer Praveen Chhetri was available at site to record the event:

Submerged Darjeeling - Kalimpong road: Two women from Teesta bazar wistfully look at the flooded Kalimpong-Darjeeling road on 05Oct2025. 
I took the photo (below) from almost the same spot on the Teesta bridge in 2024 when the river had receded and the submerged homes alongside the road were visible.
This road passes thru Teesta bazar and every time it is flooded, we have to take a lengthy 6hr detour instead of the normal 2hrs to/from Darjeeling.

Drone image of the flooded Darjeeling-Kalimpong road at Teesta bazar on 05Oct2025

On 05Oct2025, the Teesta submerged this junction of NH10 and the road to/from Darjeeling (where motorcyclists have assembled). In the distant, the Teesta bridge linking Gangtok and Kalimpong is visible - the river is huge and stretches from one bank to the other.

Trees, stumps and debris were again dumped on the Darjeeling-Kalimpong road below the Teesta bridge by the floods of 05Oct2025.

Almost an annual event - flooded homes in Teesta bazar on 05Oct2025.

The Teesta flowing bank to bank on 05Oct2025. NH10 which connects Siliguri to Gangtok is blocked at Rabi Jhora which is a small flooded bridge on the right bank. This extreme event took place at the peak of festivities and Puja season with hundreds of vehicles choking the highways and roads. 

All photos (except one taken in 2024) by Praveen Chhetri @ Junkeri Studios, Kalimpong. My grateful thanks to Praveen (junkeristudio@gmail.com) for photographing the event as a historical record. 
Talking about historical records, I have a small story to recount  about the Teesta bazar👇

A walk back thru time

I was 17yrs old when the October 1968 disaster struck the Darjeeling–Sikkim Himalaya — 57 years ago now. About a week after 04Oct1968, my cousin, a friend, and I walked down to Teesta Bazar, where I took a few photographs with my father’s Zeiss Ikon bellows medium-format camera. Those photos, badly damaged over time, had long been missing until yesterday, when I stumbled upon them while rummaging through some old prints. Thanks to Praveen for scanning them — I’ve since worked on the images in Photoshop and an AI restoration tool and managed to recover four photos. Though still blurred and damaged, they now stand preserved for posterity, alongside those from Das Studio

The Andersen bridge after it was brought down by the Teesta during the 1968 flood. The blurry figures standing on the right are my cousin and friend.

Teesta bazar from the opposite bank. This area sustained a huge amount of damage including a petrol pump and all the equipment which were swept away by the rampaging Teesta. The remains of the Andersen bridge are still visible today.

Apologies for this image which is really bad - but still you can make out some damaged homes and a lot of scars which are landslides... this area is (I think) where Krishnagram now stands in Teesta bazar.

This part of Teesta bazar is where the community hall and the haat bazar stands today. You can distinctly see the road going up to Darjeeling and Peshoke in the upper right.

Praful Rao
savethehills@gmail.com

9475033744

Extreme rainfall event in the Darjeeling district: 04/05Oct2025 (Part IIIA - 'Overall damage and fatal landslides')

 BEFORE & AFTER LANDSLIDE IMAGES FROM NATIONAL REMOTE SENSING CENTER (NRSC)

The Darjeeling district, particularly the Kurseong and Mirik subdivisions, experiences extremely high annual rainfall, averaging over $3000\text{ mm}$. This concentrated precipitation, which falls largely between May and October, makes the region highly susceptible to recurrent landslides, resulting in a long history of such events:
September 1899 (72 fatalities reported in the region).
October 1968 (A massive landslide event combined with a great flood, resulting in over 667 fatalities in Darjeeling, Kalimpong, Teesta Bazar, Lebong, and other areas). Covered in our blog, see here.
June-July 2015: Landslides occurred in Mirik, Tingling, Nimki Dara, and Sukhia Pokhari. Covered in our blog, see here.
October 2025 Disaster: Relentless overnight rainfall on October 4 and 5, 2025, triggered one of the worst recent landslide disasters. Rainfall data of the event is given below:

Fatalities
As per media reports 32 people lost their lives in the deluge with 21 people dying in Darjeeling and 9 & 2 losing their lives in Jalpaiguri and Cooch Behar respectively.

Damage
The disaster damaged 81 roads, 11 bridges, innumerable culverts. It breached 1128m of embankments and washed away 12,680m of river protection works were washed away. Electrical infrastructure was also badly damaged with 272 transformers and 1340 poles being restored till 16Oct2025. Several schools, health centers and drinking water systems were also damaged. Massive damage was reported to the tea industry as well.The tables below will be updated:

Fatal Landslides 

1. Toklang Dara Gaon (Coords: 26.869383N, 88.192072E), Mirik subdivision, Darjeeling district. ('Gaon' is 'Village' in Nepali/Hindi)

Four members of a family were killed by the landslide at this home on 05Oct2025

a. Fatalities: Four — all members of a family who had returned to their home in Taklong  from Salbari, Siliguri, after eight years to celebrate the Dasain festival together.
b. Time of Occurrence: Around 3 a.m. on 05Oct2025.
c. Details: This large landslide occurred during intense thundershowers which moved in from Nepal on 04Oct2025 afternoon. According to local residents, a huge boulder perched on the hilltop — which had earlier been reported to both the local administration and the media — was dislodged by the heavy rainfall, triggering the disaster. Locals also pointed out that inadequate drainage on a newly constructed road above the site had added weight to the slope crown, contributing to the failure.
d. Damage: In addition to the four fatalities, several livestock were lost, and four houses — including a large building — were damaged.
During their survey, the SaveTheHills (STH) team observed numerous landslides along nearby roads, underscoring how road construction and drainage issues remain major triggers for slope failures in the Himalayan terrain.

    Toklang Dara Village (gaon) in Mirik. The hills in the distant are in Nepal

Drone image of the large landslide at Toklang  Dara (Mirik) which
killed 4 people on 05Oct2025.

Large boulders which were dislodged by the intense rain caused immense damage to the village besides the fatalities.

2. Jasbeer Gaon (Coords: 26.895N, 88.2064E) Mirik subdivision, Darjeeling district. ('Gaon' is 'Village' in Nepali/Hindi)

a. Fatalities: Two (husband and wife killed in the landslide - the daughter, aged 15, survived)
b. Time of Occurrence: Around 3 a.m. on 05Oct2025.
c. Details and damage: This massive landslide at Jasbir Gaon extends nearly 1,200 metres down to the Rangbhang River (see map above). According to local residents, a fissure that appeared on the road at the crown of the slope allowed water to seep in, eventually triggering the collapse.
The impact was devastating: once-flourishing orange orchards were wiped out, homes and livestock were lost, and two lives were tragically claimed. The disaster has left deep scars on the landscape and on the community’s livelihood. Many displaced families are now taking shelter in a relief camp at Soureni Bazar, Mirik.

Drone image of Jasbir village landslide near the crown of the landslide.

Drone image of the landslide where it meets Rangbhang river at the base of the mountain. The slide is more than 1.2km in length from the crown (top) to the toe (bottom).

Jasbir Gaon fatal landslide. Two people lost their lives in this area in the early hours of 
05Oct25. In just a few minutes, the massive landslide swept through the slope, turning once-bountiful orange orchards into a barren, rocky wasteland.

Rangbhang river below Jasbir Gaon. The overnight rainfall on 04/05Oct2025 transformed this tiny stream into a raging torrent which gouged out large parts of the valley in its path.

3. Bishnulal Gaon, 11th Mile, Mirik subdivision (Coord 26.89512N 88.17635E)

a. Fatalities: Two of a family (son 9yrs, niece 11yrs of Rabin Chhetri)
b. Time of occurrence: Early hours of 05Oct2025.
c.  Details: Tragedy struck a home at Mirik when a landslide claimed the lives of a nine-year-old son and eleven-year-old niece of Rabin Chettri. The family’s house was completely destroyed, and their neighbor’s home was left half-buried under the debris. Continuous rainfall since the previous evening had saturated the already unstable slope. Just a year earlier, a kutcha road had been hastily constructed along the crown of the hill, using heavy machinery and without any retaining walls or proper drainage which according to Rabin may have caused the landslide. The presence of four borewells at the toe of the slope, coupled with waterlogging, may have further destabilized the ground. When the slope finally gave way around 3:30 a.m., the debris not only engulfed the houses but also buried the borewells, cutting off water access for the entire neighborhood.

Drone image of the slope failure and where two children died at 11th Mile, Mirik on 05Oct2025.

Frontal view of a smashed home where the fatalities occurred.

Partly buried borewell at the base of the landslide. Locals suspect that the water from these wells may have exacerbated the slope failure. Right now, drinking water is a problem for the community in the area because the borewells are non-functional.

Drone image of the landslide gives a clue as to what may have caused the landslide. On the extreme left, there appears to be a jhora or stream which could have led to the slope failure. Notice the reddish color of the soil and the absence of any boulders and rocks.

4. Lakeside landslide, Mirik municipality (Coords:26.89130, 88.18340)
a. Fatalities: Three of a family
b. Time of occurrence: At around 3.00am on 05Oct2025.
c. Details: The family members that the STH team talked with were incredulous that a landslide had taken place in their area at all. They clearly said that the area had no instability or drainage problem and that the only reason that the small slip had taken place was that soil from a nearby construction had been dumped above their home and that during heavy rainfall, this soil had  slid down in the early hours of the 05Oct2025, and extinguished the lives of 3 members of the family. In fact, the whole event had occurred so quietly that they only discovered the landslide and the death of their members at around 6am on 05Oct2025.

Where three lives were snuffed out at around 3am on 05Oct2025 Lakeside, Mirik.

Notice the red soil of the area which many locals say is the reason why Mirik is so landslide prone. The landslide at 3 am of 05Oct2025 went completely unnoticed by other members of the family who only discovered it later at around 6am. By that time, two elders of the family and a relative who was visiting them from Nepal had been dead for several hours, buried by the red soil in a small landslip. 

The red, granular soil tends to lose its cohesion and frictional strength when it becomes wet or moist.

STH team interviewing family members at Lakeside, Mirik during their survey.

Report on fatal and other landslides will be continued.

Report by STH Survey team
Praveen Chhetri (all drone images and photographs): junkeristudio@gmail.com
Steve Rai(interviews and videos with Praveen)
Shreya Gurung (Interviews): shreyagurung07@gmail.com
Yukta Acharya (Interviews and records): yuktaa1999@gmail.com

with sincere thanks and appreciation to Roshan, Rajen bhai and Priya of Darjeeling Himalaya Initiative (DHI)
and also to Aachal (Anugyalaya DDSSS) for helping with resource persons and information.

Praful Rao
savethehills@gmail.com
9475033744

The Teesta Valley GLOF disaster of Oct2023 in WMO 'State of the Climate in Asia 2023' report

The above report has been released by WMO (World Meteorological Organization) on 23Apr2024 and contains a comprehensive account of the climate and extreme events in Asia in 2023:

The Teesta Valley GLOF disaster has also been mentioned prominently in the report (page 18) and it vindicates our stand on it - that it was the largest GLOF disaster in the Himalayas in the recent past and YET it hardly received any attention from the national media or the state governments and the centre.
After the WMO report however, several national level e- papers have carried the story:

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

GLOF in North Sikkim triggers flashfloods down stream

We have had incessant rain in our region for the past 24hrs or so and as always STH has tracked the cloud movements and put updates in our WhatsApp group 'HAZARD ALERTS 1 & 2' with a view to provide some rudimentary early warning to the community.

Perhaps it is this incessant rainfall, due to a circulation over Jharkhand, which triggered the GLOF in South Lhonak glacier in North Sikkim. A very technical study has been done and is available here
The abstract from the article is reproduced below:

The Teesta basin in Sikkim Himalaya hosts numerous glacial lakes in the high altitude glacierized region, including one of the largest and the fastest-growing South Lhonak Lake. While these lakes are mainly located in remote and unsettled mountain valleys, far-reaching glacial lake outburst floods (GLOFs) may claim lives and damage assets up to tens of kilometers downstream. Therefore, evaluating GLOF hazard associated with current and potential future glacier-retreat-driven changes is of high importance. In this work, we assess the future GLOF hazard of the South Lhonak Lake by integrating glacier and hydrodynamic modeling to calculate the lake's future volume and hydraulic GLOF characteristics and impacts along the valley. We identify the increased susceptibility of the lake to potential avalanche impacts as the lake grows in the future. Here we model six avalanche scenarios of varying magnitudes to evaluate the impact-wave generated in the lake and overtopping flow at the dam. Avalanche simulations indicate that the frontal moraine is susceptible to overtopping. The overtopping flow hydraulics is evaluated along the channel assuming no erosion of the moraine. Further, we consider three lake-breach scenarios to model GLOFs originating from the lake, flow propagation, and its downstream impacts. The uncertainty in the breach parameters including breach width and time of failure are calculated to estimate the upper and the lower hydraulic limits of potential future GLOF events. Further, the uncertainty in the flow hydraulics was evaluated using dynamic flood routing of six GLOFs that originate from the lake. Hydrodynamic GLOF modeling resulted in a predicted peak discharge of 4311 m³s⁻¹, 8000 m³s⁻¹, and 12,487 m³s⁻¹ for breach depths of 20 m, 30 m, and 40 m respectively. The large-potential scenario suggests that maximum flow depth and flow velocity at Chungthang, a town proximally located to a major hydropower station built-in 2015, could reach up to 25–30 m and 6–9 m s⁻¹, respectively. Mapping infrastructure exposed to GLOFs in the Teesta valley shows that many settlements and assets located along the river channel at Chungthang are potentially exposed to future GLOFs, indicating the need to conduct a full environmental impact assessment and potentially undertake GLOF risk mitigation measures.

I was up at 2.20am after being notified of the GLOF by a friend. I spoke to several people in Sikkim to verify the information but it was difficult to get thru and rather embarrassing to disturb a person at that time.

After becoming reasonably sure of the event, I alerted the NDMA control room at 3.33am with a request to verify the information from SSDMA. (Sikkim State Disaster Management Authority).

I was surprised at the speed at which the flood waters advanced. Luckily, most people in the low lying areas made it to higher ground, despite the non-stop rainfall and darkness. Approximate timeline of the flooding (based on information given to me this morning by a friend when the event was unfolding) is given below:

Casualties and damage:

Sikkim State Disaster Management Report
Gangtok, October 4 (IPR): The Glacial Lake Outburst Flood (GLOF) in portions of Lhonak Lake, Mangan District, which caused the rise of water levels with very high velocities downstream along the Teesta River Basin in the early hours of October 4, 2023, has caused severe damage in Mangan, Gangtok, Pakyong, and Namchi Districts.
The lake outburst in portions of Lhonak Lake in North Sikkim caused a rise in water levels with very high velocities near about 15m/sec, crossed the CWC Melli site measuring 227 m, near about 3m above Danger Level, at 0600 am.
According to the Central Water Commission (CWC), the flood occurred at midnight on October 3, 2023. Simultaneous flood forecasts for both India and Bangladesh were made at 0600 hrs and 1400 hrs. The river Teesta is flowing below the warning level at CWC Domohani FF Station. The water level at 0600 hrs is 84.83m and is expected to cross its warning level within 6 hours.
Similarly, around 1 a.m. on October 4, 2023, the major flooding of the Teesta River was reported from Chunthang. Likewise, by 2:30 pm, the flood had reached the lowlying areas of the remaining districts, causing serious destruction to public properties and public infrastructure. The communication network under Mangan District surrounding Chungthang and its pheriphery has been affected. Districts sprung into action and immediately initiated the evacuation of the people from the lowlying areas.
Further, the SDRF team from the State Home Guard and Civil Defence, Gangtok, and NDRF Pakyong has already been deployed in the affected areas.
As per  the report received from the SSDMA, the following damages have been reported from the districts:
(i) Mangan District: Chungthang cut off due to the Toong Bridge collapse. Phidang Bridge collapsed. Four pucca houses at Phidang were washed away. Two houses at Dikchu were washed away. Houses along the river line are in danger, and two GREF labourers are reported missing at Sangkhalang, as per information received from GREF sources and one person missing from Phidang.
The GREF Crusher Plant and Old Police Barrack have been washed away at Toong, and four people have been reported missing.
Forest Guest House and two units of government quarters at Sangkhalang has been swept away.
(ii) Gangtok: Four injured have been taken to Singtam Hospital. 25 people have been rescued by SDRF, more rescue is underway.
(iii) Namchi district: LD Kazi Bridge washed away. Indreni Bridge washed away. A relief camp was set up at Namphing Sai Mandir. As of now, 500 people have been kept in the relief camps, and permanent relief has been set up at  Pranami Mandir.
(iv) Pakyong district: Two minor injuries, one dead in West Bengal, and one person is under observation at Rangpo PHC. 23 army personnel have been missing and one person has been rescued at Bardang.

SSDMA

Fatalities/Missing
Known missing thus far are 23 army soldiers who were presumably swept away from their barracks at Bardang near Singtam by massive 15-20' waves of the Teesta river.
20 civilians are also reported missing.

Damages
Proper estimation of the damages in Sikkim and W Bengal may take some time. However, the major damage are as follows:

1. Sikkim Urja Dam at Chungtang, a 1200 MW Teesta Stage III Hydro Power plant was partly swept away by the GLOF resulting is huge release of water.

2. Indreni bridge at Singtam (30km from Gangtok) and another bridge at Baluatar were swept away. Several other bridges have also been washed away.

3. Control room of NHPC Stage V Dam at Dikchu has been damaged.

4. NH10 and communication lines all over Sikkim and Kalimpong district in W Bengal have been severely damaged at many places. Road towards Darjeeling from Kalimpong is severely damaged at Teesta bazar.

5. Three districts in Sikkim including Mangan (north Sikkim), Pakyong and Gangtok (east Sikkim) were severely affected. Mangan was the worst hit.

Will update this continuously over the next few days as more information is available

Incredible photos (includes drone imagery) by STH photo/videographer Praveen Chhetri of the GLOF devastation at Teesta bazaar (taken in the morning on 04Oct2023)

Why at Teesta Bazaar only and not in Sikkim?
Because there is no road access anywhere - National Highway10 (NH10) towards Siliguri is damaged and eroded, as is the highway to Gangtok. The road to Darjeeling from Teesta has been 'eaten away' by the floods this morning

As I write at 8.pm on 04Oct2023, it continues to rain in Kalimpong, Darjeeling, Kurseong and I am sure in many places in Sikkim for almost 36hrs now, at varying intensities.
Hope things get better tomorrow.

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