Changes in parts a Himalayan town (Kalimpong) in 17 years

 

The lower photograph (May 2026) appears considerably greener than the one taken in May 2009. This is most likely because the pre-monsoon season of 2009 may have been significantly drier than that of 2026, resulting in lesser undergrowth, vegetation and seasonal greenery across the slopes.

The 2009 image also shows more open terraced cultivation and a clearer patchwork of agricultural land use, whereas these features appear less distinct in the 2026 photograph.

This change may partly be seasonal. Maize is normally planted during May and a good crop cover in 2026 may have obscured some of the terraces visible in the earlier image. However, a more important long-term factor is likely, the gradual abandonment of farmland caused by migration of younger populations away from rural areas to places abroad or to Indian metros. Many former agricultural slopes may now be unmanaged undergrowth and vegetation, making terraced areas less visible than before.

Across Areas A, B, C and D, several important changes are evident:

• There has been a substantial increase in built structures and settlement density between 2009 and 2026.
• This expansion would necessarily require an increase in slope cutting and road construction.
• Much of this growth appears largely unplanned, increasing pressure on already fragile Himalayan slopes.
• Inadequate or poorly maintained drainage systems in such densely populated hillside areas significantly increase the risk of landslides and slope failures, especially during periods of intense rainfall.
• The spread of unmanaged vegetation may also create an increased fire hazard during dry summer months when vegetation dries out.

The one encouraging sign in the 2026 image is the apparent recovery around the Pashyor landslide area (E). Increased vegetation cover suggests partial recovery and some degree of surface stabilization. However, in the Himalayas, vegetation recovery does not always mean that a landslide has become fully stable, as deep-seated geological weakness and drainage-related instability may still persist beneath the surface.

Overall, the photographs document the transformation of the western face of  Kalimpong from a more semi-rural Himalayan settlement into a more populated and urbanized area over the past seventeen years. They also highlight the growing challenge of balancing development with ecological and geological stability in the fragile Himalayan environment.

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

The National Highway 10 (NH10 - Siliguri to Gangtok) maintenance problem (post GLOF) begins in Mar2024

NH10 and Likhu Bhir in 2017 & 2023

MoRTH website on NH10 reads as follows:
'The highway starting from Indo / Bangladesh Border connecting Fulbari Siliguri in the State of West Bengal connecting Sivok, Kalimpang near N.H-10 and terminating at Gangtok in the State of Sikkim'. 52kms of the highway is in Sikkim, the remaining 65.97kms being in W Bengal.
Further to our earlier report on National Highway 10 (NH10), the recent rains in our region caused landslides along parts of NH10 which resulted in road blockages and traffic jams and as such the Kalimpong District Administration has closed parts of NH10 for traffic as per the letter below:

 

 

Prolonged closure of NH10 dates
Road closures for several hours on NH10 due to landslips, erosion and rockfalls etc are commonplace and take place almost daily during the monsoons. Prolonged closure dates of the highway in the recent past are as follows:-
* In 2007 and 11Jun2010 at HaatiSurey, near Coronation bridge – blocked for a week.
* 26Jun-03Jul2015 due to landslide at SetiJhora (near TLDP IV)
* 14-15Jan 2016 due to landslide at BhoteyBhir (near Rangpo)
* 06Jul2019 for almost a week at Seti Jhora

Despite several alternate routes now being available (see map below), NH10 remains the shortest distance with the least gradient changes and is the quickest way to commute from Sikkim and Kalimpong to SIliguri and the plains of North Bengal - however, it may not be the safest route anymore.

NH10 and alternate routes

DATA ON NH10 (and the alternate routes from Gangtok and Kalimpong to Siliguri)

Distances - Siliguri to Gangtok
Via NH10 - 114kms out of which approx 90kms is in mountainous terrain. Approx 60kms from Singtam to Sevoke is along the banks of the Teesta river.
a. Alternate route 1 (via Pakyong- Reshi-Algarah-Lava-Sevoke-Siliguri) - 241kms
b. Alternate route 2 (via Rangpo-Chitrey-Kalimpong-Algarah-Lava-Sevoke-Siliguri)  - 205kms

Distances- Kalimpong to Siliguri  
Via NH10 - 67kms
a. Alternate route 1 (via Ghoom -Kurseong) - 99kms
b. Alternate route 2 (via Algarah-Lava- Gorubathan-Sevoke) - 132kms
c. Alternate route 3 (across Relli river- Samthar- Panbu-Kalijhora-Sevoke)

It is estimated that approximately 3000 vehicles use the NH10 daily when permitted.

Images of landslide and traffic snarls in that part of the road

Rockfall at Likhu Bhir after rains on 23Mar2024

Traffic jam at Chitrey (Teesta) due to rock fall at Likhu Bhir, 23Nov2024

Traffic jam at Likhu Bhir on 24Jan2024 at around 6pm

 

As we have reported earlier, Likhu Bhir is an old landslide which was dormant for many years until the GLOF of 04Oct2023 reactivated it.

File photo from July2019

Also as reported, the Teesta river bed has risen by almost 4m all along the valley due to the silt and sand deposits brought down by the GLOF, which makes NH10 much more prone to subsidence/erosion (the TLDP III and IV dam activities and the IRCON tunnelling having contributed their share to making sections of NH10 more prone to subsidence, rockfalls and landslides)

Rainfall (at Kalimpong) from 19Mar to 23Mar2024
107mm.
It was surprising that very moderate rainfall, after almost 4 months of complete drought could trigger so much instability in the Likhu Bhir area.
Recently, I met a geomorphologist who said that the Oct 2023 Teesta Valley GLOF was the biggest such event in the Himalayas in the recent past. I believe him entirely.

My thanks to our WhatsApp group 'HA' members who's photos I have used :)

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

How to destablize a hill in quicktime: Nursery Gaon landslides, (Kalimpong) 07Jul2020

I had visited Nursery Gaon along with GSI Geologist Debashish Bhattacharya in Dec 2012 and blogged about it. It lies below the 7/8th mile area of Kalimpong and several landslides there were active even then. Some picture posts of our visit in 2012 from the STH blog are below:

Subsequently on 01Jul2015, following heavy rainfall, a landslide occurred again at Nursery Gaon and an entire family perished. Their bodies could never be traced.

• I am very familiar with the area which lies on the western face of Kalimpong and as such is steep and mostly rocky. Compared to the eastern face, this region has sparse population but at the crest (the 8th mile area) there is a large urban build up with several prominent schools, flower nurseries and the road (State Highway -SH12) linking Kalimpong to Teesta bazar passes thru this region.

• Kalimpong has long needed a by pass road since the SH12 passes thru town and traffic snarls are increasingly becoming impossible esp when large military vehicles have to pass thru narrow areas. To obviate routing thru the congested town area, a by pass road circumventing the urban cluster was planned. This road which was to start at 7th mile, pass below the 8th mile area and terminate somewhere in Bhalukhop avoiding the entire town area.

• The by pass road was inaugurated in 2009 (to the best of my knowledge) and rather coincidentally my first record of a landslide in the region is also of Aug 2009.

• Since then I have visited the by pass area many times, to check the increasing areas of instability along the road.
• On 07Jul2020, following heavy rains, there were reports of landslides in the area. I visited the area on 10Jul2020 and this is my assessment:

Images from my survey in the area are place below:

Size of slide is approx 60m in length

The length of this subsidence is around 30-40m

RAINFALL ON 06Jul2020 : 109mm

Having talked to affected people of the area:
1. It is well known that roads interfere with the natural drainage of a mountain and therefore are a major cause of landslides. In the case of the above landslides, this is very evident. Whereas there was little instability in this region before 2009, the incidents of landslides have increased sharply over the years.
2. This was very evident even in 2012, when I visited the area and made a pointed remark that this area would be susceptible to slope failures due to poor drainage (see first slide).
3. Sure enough, on 01JUL2015 we had a fatal landslide in the area.
4. Unfortunately even after that, nothing has improved. Merely loading the area with more concrete, stone and sand is NOT the solution and perhaps the engineers will have to incorporate some innovative ideas on how to manage the water and improve drainage.
5. High time we think seriously about how to control the instability instead of how to make money from it.

Praful Rao
Kalimpong district
Darjeeling-Sikkim Himalaya