Extraordinary rains of September end 2024 (in the Darjeeling - Sikkim Himalaya).

Until the 23rd, the month of September 2024 for us in the Darjeeling-Sikkim Himalaya turned out to be very dry and inordinately hot, prompting a member of the SaveTheHill's What'sApp group 'Hazard Alerts' to write:

'What does it mean, no rain in Kalimpong, Sikkim or Darjeeling?? Paddy fields are drying, springs and streams have dried already, this year "MUL PHUTENA", meaning ground aquifers were not recharged completely. This situation warns of the chaotic food insurgency especially to those who wait for food from farmers. Poor farmers look at the sky, it looks blue, no cloud, and he screams for his hardships and crop failure. I'm a farmer, what option do I have now??'

Another member post this cartoon about the prevailing hot weather:

Then on 24Sep2024, another LOW pressure area, in a series of bumper to bumper lows which had formed in the Bay after 17July2024, developed as shown below:

IMD issued a number of press releases about the weather systems causing the heavy rain and likely weather which would ensue:

Based on IMD and other inputs, STH posted satellite imagery and weather updates continuously during the period in our WhatsApp groups 'Hazard Alerts, Hazard Alerts 2, Hazard Alerts 3' - we also used other social media handles to publicize the heavy rainfall warnings.

Rainfall data

On 29Sep2024, IMD gave us a GREEN (ie no warning after 3 days of RED warning and 1 day of orange warning in the above period) and we had a dry day after 5 days of non-stop rain.

The average monthly rainfall for September in Sub-Himalayan W Bengal and Sikkim is 388.1mm - the 5 day rainfall of Sept2024 end, as seen above came close to or in the case of many towns, exceeded the monthly average and thus we swung from a total deficiency of rain in the first three weeks of September to a gross excess of rain, all of the large volume of water coming at the end of the monsoons when the mountains are almost saturated with water. As such the impact of this unusual heavy rains was huge in the region.

IMPACT

Firstly and most importantly, there were no fatalities even though we did have many landslides and near misses.
Road Communications: NH10
The already poor state of road communications especially in the Teesta valley suffered further set backs.

Landslide on NH10 near Teesta bridge on 27Sep2024 (27 03 40.2 N 88 25 35.3 E)

Large landslide on NH10 near Melli (27.08388889N 88.45098611E)

Other places in the Teesta Valley

Flooded Darjeeling - Kalimpong road near Teesta bridge, 28Sep2024. The debris and sand deposits by the GLOF of Oct2023 had raised the level of the Teesta river by as much as 4-5m so heavy rain
always results in the river flooding this road.

Teesta Low Dam Project III at 27Mile and the flooded Bangay bazar bridge
(26°59´38.20´´N 88°26´32.83´´E)

Flood affected areas of Teesta bazar. As mentioned earlier, the GLOF of Oct2023 has pushed the riverbed levels up by 4-5m and as such the river runs perilously close to many densely populated areas - Melli, SIngtam and Rangpo to name a few. Heavy rain in the valley invariably results in flooding of these areas.

Melli town and stadium ( 27°05´23.03´´N 88°27´28.01´´). The stadium which was entirely covered by debris and sand by the GLOF in Oct2023 had been painstakingly cleaned by the town but it has been rendered unusable by the repeated flooding of the river.

The GTA Covid Hospital (27°04´48.63´´N 88°25´50.37´´E) lying derelict on the banks of the Rangeet river since the GLOF of Oct2023. Parts of the one lane road leading up to the hospital from Teesta Bazar has been under the river for a year now and the recent rains have inundated even more areas of the road.

Other parts of the Kalimpong and Darjeeling districts

Major landslide in the vicinity of Kalimpong town at the by-pass road, 7th mile (27 04 13.9 N 88 26 56.8 E). In Sep 2024, Kalimpong received less rain than Darjeeling and Kurseong and as such we never had as many landslides.This large landslide took place on 28Sep at around3.30pm.

Subsidence due to mountain stream erosion (jhora) in a densely populated area of Kalimpong municipality (27 03 47.0 N 88 27 45.8 E). The subsidence (seen here covered by plastic sheets to prevent water ingress) occurred during daytime on 28Sep2024 when the stream was gorged with runoff from upstream paved surfaces. My concern here is that this whole area is located above a landslide prone zone on which we have done a story in 2010.

Landslide in the Darjeeling Municipal area at Hooker Road, on 26Sep2024

Landslide at Lower Bhaktey bustee in Darjeeling

Sikkim received much less rainfall in late Sep2024 resulting in much less devastation and landslides.

I am sure there were many more unreported landslides and instances of flooding caused by the unusual heavy rains and we will keep updating this blog on the reports, when received. We will also be surveying the affected areas in due course of time.

My thanks to all HA members whose images and reports I have used liberally here and elsewhere - all with the intention of recording the event for posterity.

Documentation of parts of the above report was supported by Royal Enfield, as part of their Social Mission Initiative


Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

Rainfall data of August 2024 of some towns in Sub-Himalayan W Bengal and Sikkim

The National Highway 10 (NH10) which connects Siliguri to Gangtok and is the lifeline for Sikkim and Kalimpong district runs along the river valley almost hugging the banks of the river for almost 50 odd km. The monsoons extracted a heavy price for this closeness in Aug2024 - the highway was closed for almost 20 days due to landslides and erosion.

As per the above data:

• Darjeeling, Kalimpong (in West Bengal), Gangtok, Mangan, Damthang (in Sikkim) recd almost normal rainfall.
• Kalimpong, Siliguri, Jhallong, Alipur Duar (W Bengal) and Dentam in Sikkim recd went deficient in rainfall.
• Most of the rainfall occurred in the first half of the month (see below).
  
  This was undoubtedly due to the low pressure areas and depressions which formed in the Bay of Bengal and moved towards western India, which resulted in surplus rainfall in those parts towards the end of Aug2024 (see above).
  
  

  
  

  

  Major Landslide
  A major landslide occurred in Sikkim on 20Aug2024 at Dipu Dara, just above NHPC Stage V Power House at Baluatar.
  We have covered the entire incident in our previous blog report
  

  
  Documentation of a part of the above report was supported by Royal Enfield, as part of their Social Mission Initiative
  
  
  Praful Rao
  SaveTheHills
  savethehills@gmail.com
  9475033744
  
  

  
  
  
  
  

 

Survey of parts of the Teesta Valley (Part I) in Sep2024 - Impact of a landslide on 20Aug2024 at NHPC Stage V Power Station complex at Baluatar (Singtam)-Sikkim.

NHPC has a large residential/administrative complex at Baluatar (Singtam), SIkkim (27 15 1.8 N  88 27 34.1 E) parts of which were severely damaged by the 04Oct 2023 GLOF. We have done an extensive photo report of the area here
The area also houses the power station complex of the NHPC (510MW) Stage V (Dikchu) dam which was also severely damaged by the GLOF and which we have covered in our report here
On 20Aug2024, a major landslide occurred approximately below Dipu Dara, a small hamlet on the Singtam-Dikchu road which damaged the GIS building of the power station:

Report from 'The Telegraph' on the landslide and our update.

The GIS building of the Dikchu (Stage V) power house which was severely damaged by the landslide on 20Aug2024 (photo dated 19Nov2023). The landslide occurred from behind the white building.

This technical complex adjacent the GIS building was totally buried by the landslide on 20Aug2024 (photo dated 19Nov2023).

Dipu Dara village and the landslide at the power station. Dipu Dara residents recollect hearing a loud rumble at around 7.30am on 20Aug2024.

The damaged GIS building and buried adjacent technical structures. The bridge at the extreme right hand, lower corner has been newly constructed after the old one was washed away last year (see below)

NHPC bridge across Teesta river which was destroyed in 04Oct2023 GLOF (photo dated 19Nov2023).

Close up view of the landslide and Dipu Dara. There are 5 homes in the vicinity of the landslide crown which had been evacuated and the Dikchu - Singtam road seen here was closed for 6 days. Locals say the area was a sinking zone and some blame NHPC tunnels but the fact is that rainfall was not a trigger for this landslide.

View of the landslide and parts of the NHPC complex at Baluatar (Singtam), Sikkim which lie across the Teesta river. During and soon after the landslide on 20Aug, there were rumors that the landslide had dammed the river but the width of the valley here is huge as can be seen in this photo.

The Dikchu-Singtam road at Dipu Dara (27 15 8.0 N  88 27 38.7 E, elevation 577.2m). This section of the road was closed for 6 days after 20Aug204 and the traffic diverted thru an alternate route. The landslide took place directly below this place which some locals say was always a sinking area.

Documentation of the above report supported by Royal Enfield, as part of their Social Mission Initiative


Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

 

 

Impact of the Oct 2023 Teesta Valley GLOF: Photosurvey of the Geil khola - Likhu bhir section of NH10 on 23Aug2024

NH10 winds itself along the banks of the Teesta river. Gangtok and Kalimpong are towards the right hand side whereas Siliguri is towards the left.

The monsoons have been playing truant in our region recently. Broadly speaking, after the heavy rains in Jun2024, going into mid July, we had less rain towards the latter part of July2024 and deficient rains in August2024.
The deficient rainfall is worrisome in terms of water availability in our region but has allowed the NH10 repairs to progress and yesterday (23Aug2024) the highway was declared open once more:

I photographed the Geil Khola - Likhu Bhir section on 23Aug2024 and have placed several large images of this area which has been one of the most troublesome part of NH10 for maintenance after the Oct 2023 Teesta Valley GLOF in the hope that it may benefit  researchers, engineers and especially lay people who use the highway. You might even like to compare these recent images with our report of the same area done on 18Oct2023.

With the river flowing 4-5m above pre-GLOF levels, it is now running close to the level of the road (and also closer to the IRCON tunnel as well), increasing erosion of the road and the maintenance problems. Teesta bridge is in the top right hand corner.

This image clearly shows how close the river is to Teesta bazar (top right hand corner) of which several areas are sinking and the level of the river between Rabi jhora (see map) and the Teesta bridge thru which the Darjeeling- Kalimpong is routed.

Notice the level of the Teesta as it hugs the NH10 in between Geil Khola (extreme right) and the settlement (29Mile or Baluatar) at the center of the photo.

Section of NH10 between Baluatar (settlement on the right hand side) and Teesta Low Dam Project III (TLDPIII), left top.

The Likhu Bhir section of the NH10 - perhaps the most troublesome part for maintenance as well as traffic jams.

Geil khola - Likhu Bhir - Teesta Bridge (top right) section. The post -GLOF Teesta river is flowing bank to bank even with deficient rainfall in Darjeeling -Sikkim Himalaya over the past two weeks. We still have a month or more of rains left.

Documentation of the above report supported by Royal Enfield, as part of its Social Mission Initiative

Praful Rao
SaveTheHills,
Darjeeling-Sikkim Himalaya
savethehills@gmail.com
9475033744

Rainfall data of July 2024 of some towns in Sub-Himalayan W Bengal and Sikkim

IMPACT OF THE JULY 2024 RAINS AT TEESTA BAZAR:
Some young men at Teesta bazar had started a two wheeler repair business in this shop on the Darjeeling-Kalimpong road after they shovelled out all the sand and debris brought in by the 04Oct2023 disaster (notice the damaged ceiling fans). The rains of July2024 put an end to their business venture and dreams when the Teesta river, flowing in the vicinity and almost at the same level flooded their shop again during heavy rains.

Rainfall normally peaks in July during the monsoons after which the rainfall gradually declines in August and Sept with the monsoons normally exiting our region in October.
As is clearly visible from the top data, rainfall was heavier in the Dooars area and foothills of Kalimpong district (and Bhutan hills).
IMPACT
The amount and intensity of rainfall impacted road communication a lot with NH10 and the Darjeeling - Kalimpong road being closed OFF and ON thru the month.

Even Rohini road to Darjeeling from Siliguri was closed for some time on 02Jul2024

                                Landslide near Loreto School, Darjeeling - 05July2024

INFACT NH10, WHICH HAD CLOSED ON 01JULY2024, COULD NOT BE RE-OPENED FOR TRAFFIC UNTIL 31JULY2024 - WHICH WAS THE LONGEST DURATION THAT THE HIGHWAY WAS CLOSED CONTINUOUSLY EVER - ALL DUE TO THE TEESTA VALLEY GLOF OF 04OCT2023.

Landslide on NH10, at Andheri, near Rangpo on 16July2024.

A low pressure area in the Bay of Bengal which brought in a drier spell of weather in our region after the heavy rains in the first half of July2024.

My thanks to all our What's App group ('Hazard Alerts') members whose images and stories I have used in this post

Praful Rao
with
Yukta Acharya

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