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

After the drought - welcome rains in mid - March2024 but also the adverse impact on NH10

After the devastating Teesta valley GLOF of 04Oct2023, our region went in for a four and a half month drought where we did not get a drop of rain:

Both the post-monsoon and  winter season rains went missing and with the vegetation and forests bone dry, we had forest fires much earlier than usual (SHWB is Sub-Himalayan W Bengal)

Screenshot of my post in our What'sApp group, 'Hazard Alerts' showing forest fires in Jan2024.

Forest fire in Sikkim: 16Mar2024

The drought-like conditions continued right upto mid-March2024 with acute drinking water scarcity in many of the urban centres in our region - in Kalimpong there was a 3 day waiting list for anyone wanting to buy water from the water tankers and also, I believe people have started drilling for ground water again. In the rural areas, springs dried up.

Winter rains are caused by Western Disturbances (WDs) which originate around the Mediterranean sea.
DownToEarth reported on the matter, excerpts of which are placed below:
'There has been a lack of rainfall during the post-monsoon season and next to no winter snowfall in some of the north Indian states as a result of a lack of intense western disturbances. This can affect the yield of Rabi crops in these regions and also availability of water in the mountains in general. The lack of snowfall in the mountains could also lead to a warmer than normal pre-monsoon season, with excess rainfall that could affect the harvesting period of Rabi crops. 
Winter precipitation in north India is essential to ensure people’s food and water security. While Rabi is the major cropping season encouraged by rainfall, the glacial streams and rivulets in the Himalayas are fed by melting snow and ice later in the season. 
The only source of rainfall and snowfall in the region are extratropical storms known as western disturbances (WD), which travel from the Mediterranean region. They induce cyclonic circulations in the lower layers of the atmosphere, which cause rainfall in the plains and snowfall in the mountains. They also interact with other wind systems such as the easterlies (winds blowing from the east) to cause rainfall in central India.
The WDs have been showing a decline in intensity in the past few years due to changing climate. The trend continued in the post-monsoon and winter seasons of 2023 as well.
From October 1, 2023 to January 2, 2024, 16 WDs have affected India — five in October, five in November and six in December — out of which only three have been intense and caused rainfall, according to data from the India Meteorological Department (IMD), analysed by Down To Earth (DTE).
This has caused rainfall deficits in states like Uttarakhand and Himachal Pradesh. While Uttarakhand experienced 47 per cent less rains than normal from October 1 to December 27, the deficit in Himachal Pradesh was 40 per cent, according to data from IMD.
Eight out of the 13 districts of Uttarakhand had deficient rainfall (20-59 per cent less rainfall than normal) and four of them suffered from large deficient (greater than 60 per cent deficit) rainfall. Udham Singh Nagar district had the maximum deficit of 87 per cent. 
In Himachal Pradesh, four districts had deficient rainfall and two had large deficient rainfall. Lahaul and Spiti district had the maximum deficit of 73 per cent.
“Himachal Pradesh and Uttarakhand received deficient precipitation since western disturbances during the post-monsoon were weak in nature,” Akshay Deoras, a research scientist at the National Centre for Atmospheric Science and Department of Meteorology, University of Reading, United Kingdom, told DTE.
“The western disturbance activity witnessed a southward dip in December, causing good rainfall over central India, but either deficient or scanty rainfall over most of northern India in December,” he added. 
Towards the end of November, a moderately intense WD interacted with a lower level trough in the easterlies and chased significant rainfall in central and western Indian states of Gujarat, Maharashtra and Rajasthan.
“The northwest rainfall reduction is consistent with the general decreasing trend in western disturbances and the precipitation drop over the region. But the El Nino also tends to produce colder winters over parts of this region,” Raghu Murtugudde, a climate scientist at the University of Maryland and Indian Institute of Technology Bombay, told DTE.
Murtugudde predicted that the pre-monsoon season will be warmer and probably get more rainfall because of the Arabian Sea warming. “If the summer transitions to a La Niña then we should have excess rainfall during the monsoon season,” he concluded.

The drought mercifully ended on 20March2024 in Kalimpong and also the rest of
.Sub - Himalayan WB and SIkkim with thundershowers commencing at 2.30am.
The weather systems which affected us and the cloud image is shown below:

For the past few days we have had welcome light rain in our region. Rainfall totals from 20-22Mar2024 are given below:
Darjeeling 118.6mm  Kalimpong  67.2mm  Bagdogra  92.1mm  Gangtok 46.2mm

NH10 status
We have reported extensively on the impact of the GLOF on roads and bridges in our earlier blogs including one exclusively on the part of NH10 which is now causing massive traffic jams here.
What is alarming is that after absolutely no rain for months, the first light/moderate rainfall can disrupt our communication lines so much - an issue which was pointed out by us in the report submitted to the NDMA & SDMAs of W Bengal and Sikkim on 10Nov2023.
Excerpt of the report is below

I shudder to think what will be the condition and status of NH10 when the SW monsoons set in a few months time.

Traffic jams today at Chitrey (top) and Teesta bazar on NH10

Landslide at Likhu Bhir (NH10) on 21Mar2024
(Images from Hazard Alerts What'sApp group - many thanks:)

NH10 and alternate routes in the Kalimpong- Sikkim area

Kalimpong District Administration's What'sApp message on 21Mar2024 advising alternate routes

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