Side effects of the GLOF disaster - a trucker's strike in Kalimpong (04Dev2023)

One of the major impacts of the GLOF of 04Oct2023 was its effect on road communications in the lower parts of the Teesta valley that is, on NH10 which connects Gangtok to Siliguri.

About NH10

NH10 is an arterial road, vital for the nation’s security; it is the lifeline for the border state of Sikkim and for Kalimpong district in W Bengal.

Of the 114km distance between Siliguri and Gangtok approximately 92 kms of NH10 lies in mountainous terrain and for much of this distance, the highway winds itself along the banks of the Teesta river. Several large dams have now been built on the Teesta between Chungthang (Sikkim) and Coronation bridge (W Bengal) and many more are planned. The proximity of the river to the highway and the dam activity in this area has undoubtedly contributed to the instability on NH10. The 44.9km IRCON/NFR single lane railway project between Sevoke and Rangpo which has 85% of the distance in tunnels also runs close to NH10 along the valley. This is also creating problems with the excavations from the tunnels and sludge affecting traffic.

This area receives approx 2500-3000mm of rainfall annually and has a lot of landslide activity as such there are many 'hotspots' or large and troublesome landslide areas which routinely disrupt traffic during the monsoons both in the 38km Sikkim section (from Rangpo to Gangtok) and the much longer (62km) W Bengal section (Rangpo to Coronation bridge). The entire region is in earthquake zone IV.
Normally, approx 3500-4000 vehicles ply on NH10 each day from Sikkim, Kalimpong to Siliguri.

The W Bengal section of NH10 is being maintained by the PWD (W Bengal) except for a small portion between Teesta Bazar and Geil Khola which is with NHIDCL. Maintenance of the 28km part in Sikkim from Rangpo to Ranipul is again with NHIDCL

Source: NHIDCL

Current problems   
The GLOF of 04Oct2023 shredded many parts of NH10 and for some time the Kalimpong - Melli section of the highway and the Kalimpong to 27th mile sections were closed due to damage.

Drone photo of NH10 opposite Melli bazar, on 10Oct2023 which had been eroded away by the GLOF

Part of NH10 towards Sikkim from Teesta bazar after the GLOF on 10Oct2023

Part of particularly troublesome part (between Teesta bazar and Geil khola) of NH10 on 18Oct2023. 'A' is Geil Khola which was severely impacted by the GLOF and 'B' is Likhu Bhir landslide area which has been reactivated by the GLOF.

Vehicular traffic quickly resumed on the Teesta - Gangtok section of NH10 and we could report on the impact of the GLOF at Melli and Bhalukhola on 10Oct2023. The Teesta to Coronation bridge section required more time and was only opened for light vehicles (4 wheelers) and between 6am-6pm on 21Oct2023.

On 04Dec2023 truckers from Kalimpong supported by truck unions from Sikkim and also minibus operators called an indefinite strike alleging long delays in repairing the Teesta - Coronation bridge section of the highway. See map below:

* ABCF is the normal NH10 route (in the mountains) for all vehicles . Now this route is only OPEN for light vehicles. On this road, the Siliguri - Gangtok distance is 114km and takes approx 4hrs.
* Section CF is closed for 6 wheeler trucks and buses and other heavy vehicles.
* Because of the CF closure, heavy vehicles from Gangtok and Kalimpong have to detour thru ABCDEF route ie drive thru Kalimpong town, to Lava & Gorubathan which is 228km and takes approx 7 hrs
OR
* Otherwise heavy vehicles have to follow the route shown in blue (241km) ie ABDEF route which again takes 7 hours plus.
Heavy vehicular movements disrupt traffic as such they are only permitted to ply at night thru urban areas, so I met a truck driver from Sikkim enroute to Siliguri, taking a nap at 10.00am on the roadside, because he had a 7hr drive ahead in the night.
NH717A is under construction and is not available to traffic.
A smaller alternate route from Kalimpong across Relli river then thru Samthar and Panbu and Kalijhora is available for light vehicles. However, this route is not suitable for heavy traffic and is at places desolate.
Lastly, a major problem with the alternate routing thru NH717A and the current Lava - Gorubathan routing is that this area receives almost 4000mm rainfall annually, has severe thundershowers during the monsoons and has a number of large landslide zones such as that in Nimbong.

Video of heavy night time traffic thru Pedong bazar courtesy Amod Pradhan

Damaged culvert at 11th mile Kalimpong due to movement of heavy trucks from Sikkim and Kalimpong to Siliguri.

Luckily, the strike was quickly called off with the District Administration assuring the striking transporters that the Teesta - Coronation section would be opened to heavy vehicles and buses from 10Dec2023.

In all this, the plight of truckers and bus operators who have to do a grueling 7-9hr drive from Gangtok to Siliguri is understandable - it is a tough and tiring drive, mostly along mountain roads.

Freight charges of a truck from Siliguri to Kalimpong have gone up from Rs 8,000/- to roughly double that ie Rs 15,000/- and the drivers take two days to complete a round trip.

On the other hand, the caution on the part of the district administration is also very understandable. The Teesta bazar to Sevoke section of NH10 has always been a particularly vulnerable area with numerous 'hotspots' and the GLOF has only made these places weaker. Opening NH10 to full traffic in haste and without any restrictions may expose travelers along the highway to dangerous and weak areas and we have already witnessed a number of accidents along NH10 recently and even some fatalities.

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

A strange coincidence: Landslide on NH10 at Sethi Jhora on 23Sep2020 and again on 23Sep2023 at exactly the same spot.

On 23Sep2020 a landslide occurred on the National Highway 10 (NH10) at Sethi Jhora, which was covered in the STH blog.

Of the 114km between Siliguri and Gangtok, 90km of the NH10 lies in the mountains and of this approximately 65km is along the banks of the Teesta where a number of dams have been constructed. Now IRCON is also building a tunnel for a railway which when finished approx next year end will link Sevoke with Rangpo in Sikkim.
NH10 is the lifeline for the state of Sikkim and Kalimpong and also a strategically important road and supply route for the Indian Army.

I have reproduced a press clip & photo from the STH blog dated 26Sep2020 below:

Exactly, 3 years later at the same spot (Coordinates 26.93946N 088.44148E, Elvn 233m) and again on 23Sep, an almost identical landslide occurred due to which National Highway10 from Siliguri to Gangtok is closed for traffic since 24Sep2023 (see image below) till date.

Rainfall in Kalimpong on 23Sep2023 was 58.4mm
Annual rainfall in the Teesta Valley is approx 2500-3000mm. The entire region is in Seismic Zone IV.
Why the failure occurred?
I think there are 2 factors at play. First, the Darjiling-Sikkim Himalaya is riddled with out-of-sequence faults that have been active recently. The Seti Jhora practically runs along the reactivated Ramgarh thrust fault core. Such fault cores consist of powdery crushed material that have very little strength.  The roads that run over such zones have much lower strength and load carrying capacity. If you saturate such zones with water chances are that they will liquify and cave in. September end would be a time where the monsoon has been around for a while and has saturated these zones particularly when a reservoir is also underneath it. Such a cave-in also happened in the Birrik fault core last year on the side of the road. No reservoir was involved there. Just the fault core material and rain.

- Prof Malay Mukul, Dept of Earth Sciences, IIT Mumbai

Images of Sethi Jhora (NH10) from STH's archives (2016)

Update on 27Sep2023
I was informed by a Govt Official that NH10 at Sethi Jhora was open for single lane traffic at 11.30am ie after 3 days of closure

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

Light at the end of the tunnel? : Tindharia/ Pagla Jhora landslides to be repaired soon.

STH has been associated with the Tindharia and Pagla Jhora landslides from Nov2011 when we did a big, well-attended workshop at Tindharia.
Thereafter, in July this year, after further landslides directly threatened the DHR workshop at Tindharia, we spent an entire day in the area checking the drainage and preparing a report for an expert and a friend (see here).
I am glad to say that the PWD will finally be taking up repairs of both the above landslide areas in the near future. You can read the Telegraph article here and this move I am sure, comes directly as an aftermath of the visit to Kolkata by the high powered NDMA team early this week (read here)

My only fear is, that is it too little - too late?

Because the way our bureaucracy groans and grinds along, by the time the work ACTUALLY starts, the monsoons of 2013 will be here and during the rainy season, we all know that major preventive work cannot really be done; all we can do then is fire fighting and emergency crisis management.
The monsoons were mild this year (which poses other problems as regards severe water shortage problems in the Mar-May2013) so we did not have major landslides in our area.

In an age where we should increasingly be expecting the unexpected, aren't we pushing our luck too far to for hope this trend to continue?

Praful Rao