Landslide Report 3 (Kalimpong) - Sep2020

Continuing with the landslide surveys (See Report 1 and Report 2 in this blog)  around Kalimpong town, on 09Sep2020, we went to the north eastern sector of Kalimpong along Reshi Road upto ALGARAH. This road is of strategic importance to India since much of the logistics for the Indian army in East Sikkim (opposite Doklam) goes thru this road. Also in case of NH10 being blocked, this road, via Lava/Gorubathan serves as the alternate route to Siliguri.
Regarding the survey:

• Besides the landslide/subsidence zones mentioned below, what was very evident was the serious deterioration in the condition of the Kalimpong -Algarah section of Reshi road with numerous sinking areas visible on many parts of the road, where another heavy shower or two could result in collapse of the road at multiple places.
• What should be also noted here is that the entire region has many natural springs and jhoras which during heavy rain causes a lot of erosion and landslides in the area.
  
• STH has recorded the extreme rainfall events of AUGUST 2020 and their effects in earlier posts (see 1 and 2). Further the rainfall of August 2020 is also available in this blog. All the landslides recorded below were the result rainfall during the extreme rainfall events.
  

GHATEY KHOLA subsidence

Coordinates: 27° 4'42.00"N, 88°29'50.88"E
Size of subsidence of road : approx 45m in length
During periods of intense rain, Ghatey Khola is notorious for causing landslides in this area since the runoff from the entire populated areas at the crest of the hill finds its way into this drain.
14th Mile sinking zones
The 14th mile sinking areas have been featured in this blog numerous times (see 1 and 2) and are one of the oldest landslide zones in Kalimpong. During the heavy rains of August 2020, these areas were re-activated at almost the same locations causing large portions of the Kalimpong- Algarah road (Reshi Road) to subside.
No other damage to farmland or infrastructure was observed.

Sinking areas of Algarah town

Algarah town is approx 15 kms NE of Kalimpong and has a long history of landslides. I had visited the area some years ago and marked out the sinking areas (above). WIth less rainfall in the past few years, the landslide and sinking zones had also diminished. This year with the intense rains that we have had, the hotspots have re-emerged and perhaps the most crucial one is the one in LAMA WARD which is located in the centre of Algarah town.

Coordinates: 27.1172° N, 88.5837° E
Landslide at HART spring, Dr Graham's Homes, Kalimpong

Coordinates: 27° 4'56.22"N, 88°29'48.48"E 

Photo credits: Ms Shreya Gurung

Praful Rao,
Kalimpong district
Darjeeling- Sikkim Himalaya

Rainfall data of July2016 for the Darjeeling Sikkim Himalayas and the landslide activity of the month

July 2016 was an extraordinary month for Darjeeling district and North Bengal :-
a. All 3 major towns (Darjeeling, Kalimpong and Kurseong) of the district received more than the monthly average with Kurseong getting approx 3 times the amount.
b. But is in the plains that rainfall was heaviest. Siliguri received 354mm of rain on 24Jul2016 and much of Jalpaiguri district saw some of the highest rainfall in recent memory (Slide 9). The hills of Bhutan also received very heavy rains (Slide 8)resulting in most of the rivers emanating there, flooding the plains of Dooars and Jalpaiguri district.
c. There were many, many landslides (Slide 10) all over Darjeeling district but two killed people. On 09Jul2016, two people were crushed to death when a vehicle (Slide 3) they were travelling in, was hit by a falling boulder at Sweti Jhora on National Highway (NH) 10 (linking Siliguri to Gangtok). Later on 20Jul2016, a whole family of three was wiped out at Finchey Taar, in Lodhoma Darjeeling (Slide 6)  by a landslide following heavy and prolonged rains.
d. On 21Jul2016, the district administration decided to demolish (Slide 7)13 houses on the banks of the Teesta river on NH10 at 29th Mile near Kalimpong. The houses were perilously perched on the banks of the Teesta river and on an area which was known to be subsiding.The occupants had been compensated years ago but were refusing to move.
e. Most of the rain came down in the second half of July when IMD reported the axis of the monsoon trough had shifted close to the foothills (Slide 2). The typical clouding which persisted for much of the month is see on the IR image of 21Jul2016 (Slide 14). IMD also clamped a RED warning for SHWB (Sub-Himalayan W Bengal) and Sikkim for much of the entire month of July2016 and with good reason (Slide 5).
f. The roads and highways suffered tremendous damage. NH10 had a large number of bottlenecks which make driving from Siliguri towards and into the mountains both difficult and dangerous (Slides 3 and 11). NH55 or the route from Darjeeling to Siliguri was equally precarious with the main Rohini route closing down  (Slide 12)on 26July2016 and remain so till date.
Other routes like the Kalimpong-Algarah road fared no better with large chunks of it falling off (Slide 13) or being buried under debris (Slide 4).

Praful Rao,
Kalimpong,
Dist Darjeeling