Extreme rainfall event in the Darjeeling district: 04/05Oct2025 (Part IIIB - damage caused by 'non- fatal landslides')

 Non - fatal landslides

The intense storm of 04–05 October 2025 triggered numerous non-fatal, rain-induced landslides of varying types and magnitudes across the Darjeeling–Kalimpong region (see above). Official estimates place the number of landslides in Darjeeling district alone at nearly 500. Given the scale of the event and the difficulty of surveying each site, this report focuses on a selection of the major landslides.

Seeyok Tea Garden - Sukhia block.

a. Area involved: Goddam dhura Ward 10 consists of 336 people in 87 homes.

b. Circumstances: Heavy rainfall began across the region on the evening of 04 October 2025. As the intensity increased, several residents—most of them tea garden workers—woke their neighbours and urged them to move to safer ground. One woman, an ASHA worker who had received RED alerts on her mobile phone, also went door-to-door warning others of the danger. Around 2 a.m. on 05 October 2025, a massive landslide struck, accompanied by a deafening roar reminiscent of an explosion. The Rangli River, normally a small stream, had swollen into a torrent, altered its course, and swept away two bridges in the area.
c. Damage: 7 homes completely damaged, 3 partially damaged. Livestock has been lost and vegetable gardens are ruined. Roads in the area are in a mess. 32 people were living in a relief camp. Many vehicles and two wheelers belonging to the community were washed away.

Goddam Dhura after the deluge of 05Oct2025. It is amazing that even after such devastation,
no one died - in large part due to the alertness of the community and timely evacuation to safer ground.

The tea industry, both in the Dooars and the hills, suffered huge losses because of the heavy rains. Here you see large landslides ruining parts of a garden - Goddam Dhura is visible in the valley below.

Drone image of Goddam Dhura on 17Oct2025. The rampage and destruction by the river is very apparent.

Taba Koshi, Mirik Subdivision (Coords 26.921391N 88.173500E)

a. Area: Taba Koshi is a series of around 40 homestays along the Rangbangh river which came up during the time of Subash Ghisingh and which started flourishing once road communication links from the area to Siliguri, Mirik and so on were established.
On 04Oct2025, due to the festive season, almost all the homestays were full with tourists from the plains.
b. Circumstances: As in other areas, rainfall started during the day on 04Oct2025 but intensified after 6pm and became really heavy later. Noticing the Rangbangh river had started crossed all danger levels, the locals started evacuating their guests to safer places after midnight. The power supply which had been erratic, thru the day because of the intense lightning on 04Oct2025 went OFF altogether at night so everything had to be done in pitch darkness and in heavy rain. So it was nothing short of a miracle that no one died.

c. Damages/loss: Many of the homestays were damaged as the Rangbangh river surged into the compounds and swept away vehicles as well as parts of the homestays in the early hours of 05Oct2025. There was significant damage to roads as well as to power lines and poles.

Damage to homes and infrastructure at Taba Koshi by the Rangbangh river - photo taken on 17Oct2025 more than two weeks after the deluge.

The Rangbangh river seen here is by all accounts a tiny stream which on the 05Oct2025 became a roaring torrent after the heavy rainfall on 04/05Oct2025. The river changed its course and threatened many homestays which were otherwise quite far from the river. Here, an earthmoving equipment is being used to correct the river's path.

The rampaging Rangbangh river caused extensive damage to roads and bridges at Taba Koshi on 04/05Oct2025.

A vehicle drives over a temporary bridge made of hewn pipes because of damage to the original bridge by the river on 05Oct2025

A smashed vehicle lying on the banks of Rangbangh river. Many such vehicles were lost because the homestay owners never believed the river, otherwise a tiny stream was capable of such devastation.

Massively eroded part of a homestay at Taba Koshi.

Damaged parts of a homestay and power lines at Taba Koshi, Mirik.

On 05Oct2025, a tiny stream (Rangbangh river) transformed into a rampaging torrent and brought down these massive boulders to a homestay at Taba Koshi.

This is the heart of tea country in Darjeeling district and the havoc wreaked by the rain and ensuing landslides is huge. Large parts of tea gardens have been severely mauled by the disaster o 04/05Oct2025.

Report by STH Survey team (which will be updated as and when possible)

From Left to Right
Steve Rai(interviews and videos with Praveen)
Yukta Acharya (Interviews and records): yuktaa1999@gmail.com
Shreya Gurung (Interviews): shreyagurung07@gmail.com
Praveen Chhetri (all drone images and photographs): junkeristudio@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

Extreme rainfall event in the Darjeeling-Sikkim Himalayas: 04/05Oct20205 (Part I - 'The Rainfall')

 Thus far, in the SW monsoons of 2025 our region saw a deficiency of rainfall:

Sept2025 was especially dry in Kalimpong and with the monsoons expected to exit our region on 10Oct2025, one did not expect a major rainfall event.
What has been happening, however is that the Bay of Bengal has been inordinately active with bumper to bumper low pressure areas forming and many of them, after moving over land in a north westerly direction reaching as far as Rajasthan leading to excess rain in a normally arid area.

Origin of the extreme rainfall event.
Around the 29Sep2025, I posted a notice in our What's App group 'Hazard Alerts  or HA' stating a LOW was expected (by IMD) in the Bay on 01Oct2025:

The LOW pressure formed as forecast and quickly intensified into a depression by 02Oct2025

The above image was posted in our Whats App group (HA) on 02Oct2025,showing location of the depression, the forecast track and warnings issued by IMD.
An update to the forecast track of the 'deep depression' now showed the storm moving in a 'nearly northward direction' instead of the normally NW direction.

As forecast, the storm (now a well marked LOW) on 03Oct2025, reached parts of east UP (see below) and was almost stationery there until 04Oct2025.

The storm finally started moving as predicted in a NNE direction, heading directly towards Bihar, SHWB (Sub Himalayan W Bengal) and Sikkim at approx 3pm on 04Oct2025 (yesterday), below:

In the top image, do note the density of lightning strikes which were taking place.

Rainfall data
03Oct2025: Despite having a RED warning for heavy rain, our entire region received very little rain. I distinctly recollect that in Kalimpong (my home), it was a densely overcast day which turned stormy around midday but except for some drizzle, there was no precipitation.

 04Oct2025: I was monitoring the Davis Automatic Weather stations in our area and we had light rain from  around midday. At Kalimpong, it started thundering in the late evening and by 7.30pm, the thunder had intensified. Thereafter, the rainfall, lightning and thunder continued thru the night with little or no break

windy.com image of 11pm/04Oct, just when lightning and rain was increasing over our area. The storm had moved from its earlier location and was approaching us from the SW.

Rainfall Intensity at Kalimpong

The above graph showing the rainfall intensity at Kalimpong on 04Oct2025, also shows the duration of the rainfall. Peak intensity of rainfall almost hit 150mm/hr and almost the entire 158mm of rain came down between 8pm and 4am ie 8hrs.

Lightning strikes at 3.30am/05Oct2025. The storm exited our area and continued NE wards about an hour later having killed 23 people.

Rainfall readout from our Davis AWS at Kurseong at 4.13am on 05Oct2025 (today). Kurseong is known to have heavy rainfall and has some very large landslides there. The rainfall from the extreme event was 393mm.

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

We will cover the casualties as well as the damage done by one day's rainfall on 04/05Oct2025 in Part II to this post.

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