Climate Change and Its Impact on Lindur Village

Lindur Village, situated in the Lahaul and Spiti district of Himachal Pradesh, India, stands at an average elevation of 3,328 meters above sea level. Recently, this area has shown clear signs of subsidence and creep movement, particularly intensified during the monsoon season of 2023. Due to the subsidence of the land, the agricultural land and houses are showing cracks, which are increasing in width every month now, as said by locals.

The study area map (a) Himachal Pradesh administrative boundary (b) Elevation map of the Lahaul and Spiti District (c) Satellite image of Lindur village and crack locations

A team from the Indian Institute of Technology Mandi, comprising two geologists, Nitesh Dhiman and Ankit Singh and two glaciologists, Ipshita Priyadarsini Pradhan and Kirti Kumar Mahanta, led by Dr. Dericks P Shukla investigated the subsidence area of Lindur village from 3/11/2023 to 4/11/2023. The team investigated the possible reason that led to the formation of cracks both in the agricultural field near the banks of Jahmala Nullah and several houses in the village. The presence of rock glaciers in close proximity to the village is particularly concerning. The Initial scientific investigations by the team suggest that these disturbances are closely connected to the movements of rock glaciers and permafrost surrounding the village.

The presence of extensive rock glaciers in the vicinity of the Lindur village may be a potential contributor to the observed crack. Lindur Village's topography indicates that rock glaciers are integral to the local geological settings. The alignment of the observed crack with the flow path of rock glaciers suggests a potential correlation between the two phenomena. Rock glaciers are highly sensitive to climate variations and they contribute to ground movement and deformation, exerting pressure on the underlying terrain. As these formations slowly move, they create stress and strain in the surrounding areas. The interaction between rock glaciers and the underlying permafrost layer may be a key factor in the development of the observed crack.

The potential coupling of these geological features raises questions about the magnitude and duration of their influence on the crack's formation.

Recognizing these dynamics is essential for developing strategies to adapt to and mitigate the effects of climate change and geological instability, ensuring the preservation of Lindur Village and similar communities. This situation underscores the broader implications of environmental changes and the critical need for comprehensive climate action.

Preventing Catastrophic Landslides: Surveying MBT Proximity

Landslides are a concern in hilly areas. In the recent disaster, Himachal Pradesh was hit by landslides, due to which many people here had to bear the brunt. Actually, landslides happen only once at some place. But due to the vibration and structure of the earth, some areas become hypersensitive. Of these, the Kotrupi one is close to a similar structure which is called Main Boundary Thrust (MBT) in geology. Due to these reasons, this place became the cause of a catastrophic landslide in 2017 and the death of 46 people. Due to which this area continues to show its form even after the horrific incident of 2017. It is clearly visible in the satellite image how the area before the landslide is expanding. Thus, to detect the new unstable region, Nitesh and Ankit, research students from Disaster Extreme and Environment Remote Sensing Laboratory (Dexter) and IIT Mandi, conducted a drone test of this area (October 2023). The results obtained during the testing phase revealed that the coated areas are still structurally unstable, and the tension cracks seen above indicate instability. Therefore, a thorough survey of the areas near the MBT is important so that a catastrophic incident like Kotrupi can be prevented.

Hindi

भूस्खलन पहाडी क्षेत्रों में एक चिंता का विषय हैं। हाल की आपदा में हिमाचल प्रदेश को भूस्खलन से दो चार होना पड़ा, जिसका खामियाजा यहाँ के लोगों को उठाना पड़ा । यूँ तो भूस्खलन एक बार ही किसी जगह पर होती है। परतु धरती के कम्पन एवं रचना के चलते कुछ क्षेत्र अतिसंवेदनशील हो जाते हैं। इन्ही मे से कोटरूपी भी ऐसी ही संरचना के नजदीक है जिसे मूविज्ञान में मुख्य सीमा जोर(MBT)कहते है, इन्हीं कारणों के चलते यह स्थान 2017 में भयावह मुस्खलन का कारण तथा 46 लोगों की मौत का कारण बना | जिसके चलते यह इलाका 2017 की भयावह घटना के बाद भी अपना रूप दिखाता रहता है। उपग्रह छवि में यह साफ दिखता है कि कैसे पूर्व मुस्खलन का इलाका बढ़ रहा है। अतः नये अस्थिर भाग का पता लगाने, आपदा चरम और पर्यायवरण सुदूर संवेदन प्रयोगशाला (Dexter) आई आई टी मंडी स्थित शोध छात्र नितेश एंव अंकित ने इस क्षेत्र का ड्रोन परिक्षण किया (अक्टूबर 2023) | परिक्षण के दौर दौरान प्राप्त परिणामों से यह पता चला कि कोटरूपी क्षेत्र अब भी संरचनीय रूप से अस्थिर हैं , तथा ऊपर दिखती तनाव दरारें अस्थिरता की ओर इशारा करती है।

अतः MBT के निकटवर्ती इलाकों का गहन सर्वेक्षण महत्वपूर्ण है जिससे कोटरूपी जैसी भयावह घटना को रोका जा सके ।

Unveiling Vulnerabilities: Assessing Subsidence Risks in Himachal Pradesh's Monsoon Season

The South Asian monsoon, which spans from June to September, brings about 80% of annual precipitation to the region. In 2023, this same monsoon period poured unprecedented rains in Himachal Pradesh causing havoc and loss (https://reliefweb.int/report/india/local-situation-report-0122023-16082023). For instance, the state witnessed 224.1mm of rainfall during five days between July 8 to July 12, which is a deviation of 431% increase from average rainfall, the highest since 1980. According to reports, on July 9, the Kullu district saw 131mm of rainfall in a single day which is the highest since 1971 causing loss of road infrastructure and lives. A monsoon surge, coupled with a western disturbance has led to extreme events resulting in flash floods, cloudbursts and associated landslides, subsidence and sinking of land(https://environicsindia.in/2023/09/08/preliminary-analysis-of-2023-disaster-across-himachal-pradesh/#:~:text=Three%20extreme%20spells%20(8%20to,some%20of%20the%20worst%20affected). Intense rainfall than normal tends to make more infiltration providing more water into the soil and below lying rock layers. This extra water when spills into nearby channels causing slow creep readjustment of the whole area in the form of subsidence. Similar subsidence events were reported in Sainj-Gushaini village where the permanent structure showed huge cracks and associated deformation. The members of the DExtER lab(IIT Mandi), visited the site in the Kullu district for a related study. The site intercepted deformation in the form of cracks in the houses, sinking of road etc. State of art PS-InSAR, SAR interferometry was performed in the area to decipher the rate of displacement. The results showed a high displacement rate (from -58mm/yr to 68mm/yr) at various locations of the village . Thus, It is concluded that the population dealing in the valley is vulnerable which will subsequently increase in the coming monsoon !