Shimla
During 2024, the monsoon was active during the period 27th June to 2nd October 2024 and the State received a total rainfall of 600.9 mm which is about 18% less than the normal. This year the peak monsoon months i.e. in July a total of 180mm rainfall against the normal rainfall of 255mm was recorded, whereas in August the total rainfall was 243 mm against the normal of 256 mm and in September, the trend was slightly positive by about 4% i.e. a total of 734 mm rainfall was recorded this year. Sh.D.C.Rana, Director-cum-Spl. Secretary (DM) informed that during the monsoon months, the State experienced a total of 54 incidents of cloud burst/flash floods with a total human loss of 65 out of which 33 are still missing. Besides this, a total of 47 incidents of landslides also occurred wherein 5 people lost their lives, and the State experienced a financial loss of about 1363Cr during 2024 monsoon. He further said that most of the damage occurred during the intervening night of 31st July and Ist August was in the Kullu, Mandi and Shimla district which were worst affected, wherein a total of 55 people lost their lives in these three districts only. As far as the technological interventions in the disaster affected areas are concerned, Additional Chief Secretary (Rev) , Sh. Onkar Chand Sharma informed that said that Space borne platforms by virtue of its repetitive and synoptic coverage, it has become possible to make the post disaster damage assessment with the help of NRSC Hyderabad and State Centre on Climate Change of the HIMCOSTE. The high resolutions satellite data has been successfully utilized for making post disaster assessment of flood affected areas along Samej and its surroundings, which was the worst affected in Shimla district wherein a total of 33 people out of total casualties out of 55 were reported from this village only. The Samaj is small village at an altitude of 1515mts above MSL and is located at 310 32’ 32.84” N Latitude and 770 41’ 54.05” E Longitude along the Samej khad that is a small tributary of Satluj River and joins it on its right bank at an elevation of 1060mts opposite to Jhakri near Rampur in district Shimla at 31030’ 07.69” N Latitude and 77042’ 26.05” E Longitude. The satellite data analysis reveals that, a flash flood occurred due to very heavy precipitation in the upper catchments of the Samej khad at an elevation of about 5434 mts above MSL from where it originates near the Nain Sarovar on ridge top which is roughly around 2Km from the Srikhand Mahadev on its southern side leading to very heavy flash floods in the Samej khad and its adjoining khads mainly the Kurpan Khad on its right and the Ghanvi khad on its left leading to maximum damage in Samej and Kurpan khads mainly (Image-A). Post event, a team from HPSDMA led by Director (DM) visited the affected area of Samej and Bagipul to make the preliminary assessments. Since the event was occurred during the monsoon period, so data acquisition for the cloud free images is a very challenging in the mountainous regions and thereafter preliminary damage assessment was carried out using best available IRS Resourcesat 2 LISS IV satellite image of 05th August 2024 having spatial resolution of 5.8 mts followed by Satellogic Satellite Image of 17 August 2024 having spatial resolution of 70cm.
As per the high-resolution images received from National Remote Sensing Centre (NRSC) Hyderabad that the water spread was increased from 35mts to 118mts after the flood event, whereas in the Kurpan Khad near Bagipul the water spread was increased from 38mts to 218 mts respectively.
From the LISS IV satellite image of 05th August 2024, it is observed that major contribution of the inflow was from the left bank i.e along the Samej khad.
The channel width observed to be enhanced from appox. 35mts (pre disaster) to appox. 118mts (Post disaster-Image B).
From the analysis of high-resolution image of Satellogic Satellite having spatial resolution of 70Cm acquired on 17th August 2024, it is observed that the major destruction was to the built-up area that falls on the fluvial terrace near the confluence of two streams comely washing away about 15-16 houses along with heavy flow of water (Image- C).
Image-D reveals the extent of damage further downstream of the confluence reflecting the loss to the road sections and the houses along the riverbanks within the flood plains which were completely washed away.
Image-E reflects how the flood water has affected the river course of the Kurpan khad enhancing the water spread from 38mts to 218mts at some places.
The cloud burst events are mainly because of the intense monsoon activity, orographic lifting, localized convection and potential climate changes being felt over the mountain in the form of enhanced warming has collectively contributed to extreme rainfall events leading to cloud burst and associate impacts. Chief Secretary ,Himachal Pradesh , Sh. Prabodh Saxena informed that the State suffers a great loss every year in the form of precious human lives and to the Govt. exchequer and thus there is need to have in depth studies to understand the cloud burst phenomena involving institutions like IMD/IITM using climate model simulations, so that we could save the human lives as well as the property in the present era of climatic change as the mountains are very sensitive to climatic variations and mountain people will be the worst affected .
