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
  
  

  
  
  
  
  

 

Our adverse weather early warning work on What'sApp groups in the Darjeeling- SIkkim region: Thunderstorms of 11/12Apr2024 in Kalimpong

After the Teesta Valley GLOF of 04Oct2023, our region has been extraordinarily dry, with the erratic western disturbance activity in the winter months, robbing us of all our winter rain. In Kalimpong we had the first showers after Oct2023, between 19 & 27Mar2024 where we clocked 112.6mm. Thereafter, it has been dry with forest fires again starting in the Teesta Valley.
With regard to early warnings on adverse weather events and disbursement of information on landslides, road blocks etc, SaveTheHills has been running several very active and large What'sApp groups in the Darjeeling-Sikkim region called 'Hazard Alerts or HA' for many years now and the following cloud image on approaching adverse weather was posted in the group on 11Apr2024:

This image was posted on 'Hazard Alerts' WhatsApp group at 1.31pm on 11Apr2024 along with lightning warnings from the IMD 'Damini' (lightning warning) app. Shortly after this was done, the first storm hit our region at around 2.30pm. Wind speeds in gusts reached upto 58kmph.

This storm died down momentarily at around 4.30pm only to pick up again quickly. The following cloud image along with NOWCASTs from IMD were posted to members in the 'Hazard Alerts' What'sApp groups.

Warning posted at 5.36pm to our WhatsApp groups alerting them about another storm which was approaching.

Subsequent cloud images which show the progress of the storm from 6.45pm to 10.45pm on 11April2024

The thunderstorm which hit Kalimpong at 2.30pm on 11April2024, raged right thru the night and only ceased at around 8.00am on 12Apil2024. Surprisingly, we had only 2mm of rain however strong, gusty, westerly winds from Nepal along with lightning prevailed for more than 12hrs. The graphical analysis of the windspeed from our Davis Vantage Pro AWS is placed below:

Though there were no casualties or damage from the storm, what was unusual was its duration considering there was no major weather system (such as a depression/cyclone) near by.
Also what is possible today is to get reliable and accurate information of such weather events in advance and to disburse the same quickly to a large number of people. We have been doing this regularly in WhatsApp since Jun 2016.

Praful Rao
Kalimpong district
Darjeeling-Sikkim Himalaya

New Images released by NRSC on the GLOF (04Oct2023) at South Lhonak Glacier

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

 

The deluge of Delhi (08Jul- 15Jul2023): some data, maps and images

Meteorological conditions

The meteorological conditions which caused the flooding of Delhi in 2023 between 08July till approximately 15July2023 have already been described in the previous blog - the same conditions which caused landslides and destruction in Himachal Pradesh resulted in parts of Delhi getting flooded by the Yamuna river.

As a matter of fact, large parts of Himachal and the foothills of Haryana and Punjab form the watershed area for the Yamuna river and much of the storm water from these areas finally drains into the Yamuna (see map below).

Rainfall from these catchment areas which eventually led to the flooding is as follows:

The average monthly rainfall for Delhi with other associated rainfall data is given below:

The actual rainfall

CM of Delhi, Arvind Kejriwal made a press statement saying that on 08/09Jul2023, Delhi had received 153mm of rain and the city's systems were "not designed to take such unprecedented rain", due to which major roads were submerged, traffic disrupted, and homes and businesses inundated.
According to officials, Delhi's outdated drainage system can handle only up to 50 mm of rainfall in 24 hours.

However, what became clear was it was not only climate change or the heavy rainfall which had caused the flooding in Delhi. It was also the release of Yamuna water from Hathnikund barrage in Haryana which caused the inordinate amounts of water to reach Delhi

Also involved was the water management of Yamuna river in the 22km that the river flowed thru Delhi. The 3 barrages which managed this is shown below

 

Flooded areas and satellite images
The areas which were flooded in early July 2023 were those in the vicinity of the Yamuna river in NE Delhi and also some areas for whom it was a grim first time - parts of Ring Road, Mathura road etc.
Planetscope Videos
ISBT, Kashmiri Gate, Delhi Jal Board Area

Yamuna Biodiversity Park Area

Images

We will keep updating these inputs in the future
Update on 09Aug2023

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

STH Stormwatch: Cyclone 'Biparjoy' in the Arabian sea and a 'well marked low' in the Bay of Bengal

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

Update on landslide dam in North Sikkim (17Aug2016) : Satellite images from NRSC/ISRO

All images post by Dr SS Porwal on 'Landslide Management' WA group. I have sharpened the images and increased sizes in PS.

• Water level in the dam seem to be fluctuating, it had dropped 7' yesterday morning but increased by 5' later in the day.
•  GSI estimates the landslide, which is said to be a rock avalanche to be 1km long and width 572m. As per reports from the site, the slide is still active with large rocks still sliding down occasionally.
• The landslide dam has been breached and the outflow from the dam and water levels in the pondage are being monitored continuously.

Praful Rao,
Kalimpong,
Darjeeling